絕對壓力

表壓與大氣壓力之和。

絕對零度

熱能最低時的溫度，定義為 0 開爾文，計算結果為 -273.15°C 或 -459.67°F。

AC

交流電；以規律性重複間隔改變方向的電流。

加速度

物體或粒子相對於時間的速度變化。加速度計量測該參數（dv/dt）。組織用“g”表示。

加速度計

一種將機械運動效應轉換為與運動加速度值成比例的電信號的設備。一種感測器。一種換能器。

準確度

量測設備的訓示或讀數與被量測名額的實際值之間的接近程度。通常表示為全量程輸出或讀數的 ± 百分比。

聲學

聲音的强度。彈性體振動的性質、原因和現象；這些振動產生壓縮波或波前（波陣面），並通過空氣、水、木材、鋼鐵等多種介質傳播。

活度（ai）

一個熱力學術語，用於描述溶液中自由離子的錶觀或有效濃度。它與活度係數和濃度相關聯。

活度係數（fi）

物體i的活度（ai）與其摩爾濃度（C）的比值。它是確保熱力學計算正確性的修正因數。該係數取決於離子強度、溫度和其他參數。

單個離子活度係數，陽離子為 f+，陰離子為 f-，無法通過熱力學推導。它們只能通過使用德拜-休克爾（Debye-Huckel）定律對低濃度溶液進行計算。在這種溶液中，離子間的作用力主要取決於離子的電荷、半徑和分佈以及介質的介電常數，而不是離子的化學性質。

另一方面，平均離子活度係數（f±）或鹽的活度可以通過多種方法進行量測，如冰點降低法、蒸汽壓法以及配對的傳感電極。它是單個離子活度係數的幾何平均值：f±=（f+n+f-n-）1/n。

轉接器

用於連接不匹配部件的機制或設備。

ADC–模數轉換器

一種將類比信號轉換為等效數位形式的電子設備，可以是二進位程式碼或二進位編碼十進位程式碼。用於動態波形時，取樣速率必須足够高，以防止產生混疊誤差。

地址

標識存儲資訊單元存儲位置的標籤或號碼。

混疊

如果函數的取樣速率（fs）低於函數的最高頻率值的兩倍，則頻率呈現不明確。高於（fs/2）的頻率將被折疊回較低頻率，產生錯誤數據。

合金 11

與純銅配合使用的補償合金，作為 R 和 S 型鉑-鉑銠熱電偶的延長線負極。

合金 200/226

鎢與鎢 26% 錸（含有 26% 錸的鎢合金）熱電偶配合使用的補償合金組合，作為 200°C 以下應用的延長電纜。

合金 203/225

與鎢 3% 錸（含有 3% 錸的鎢合金）及鎢 150 錸熱電偶配合使用的補償合金組合，作為 200°C 以下應用的延長電纜。

合金 405/426

與鎢 5% 錸（含有 5% 錸的鎢合金）及鎢 26% 錸（含有 26% 錸的鎢合金）熱電偶配合使用的補償合金組合，作為 870°C 以下應用的延長電纜。

ALOMEGA®

一種鋁鎳合金，用於 K 型熱電偶的負極（OMEGA ENGINEERING 公司的注冊商標）。

字母數位

包含字母和數位的字元集。

ALU–算術邏輯單元

CPU 的一部分，在這裡對二進位資料進行數學運算。

鋁鎳合金

一種鋁鎳合金，用於 K 型熱電偶的負極（Hoskins Manufacturing 公司的商標）。

環境補償

儀器的設計，使環境溫度的變化不影響儀器讀數。

環境條件

換能器周圍的條件（壓力、溫度等）。

環境壓力

換能器周圍空氣的壓力。

環境溫度

與測試設備和儀器接觸的周圍空氣的平均溫度。

電流錶

一種用於量測電流的儀器。

安培（安）

用於定義電路中電流流動速率的組織； 組織是每秒一庫侖（6.28 x 1018 個電子）。

放大器

一種比輸入信號能提供更多的功率的設備，並將輸入信號的主要特徵放大後輸出的裝置。

振幅範圍

資料在時域或頻域圖形顯示中的 Y 軸範圍。通常用對數顯示（dB），但也可以是線性顯示。

振幅

測得的從最高點到最低點的運動距離，如機械體的振盪或電波形的峰-峰擺動距離。

類比輸出

一種電壓或電流訊號，它是量測參數的連續函數。

模數轉換器（A/D 或 ADC）

將輸入的類比信號電平轉換為二進位數的裝置或電路。

風速計

量測和/或顯示空氣流速的儀器。

埃（埃格斯特朗）

10 的負 10 次方米（10-10）或一毫微米，用於定義光波長的組織。符號為 ‰。

角頻率

描述物體或點沿圓周運動的頻率，稱為圓頻率 O，是每秒週期數（cps）乘以常數（2）的結果，用每秒弧度表示（2πf）。

陰離子

帶負電的離子（Cl-、NO3-、S2-等）。

ANSI

美國國家標準協會。

防積分飽和

這是三模式 PID 控制器中的一個特性，防止積分（自動重置）電路在溫度超出比例帶時工作。

應用程序

執行特定任務（例如文字處理）的電腦程式。

ASCII

美國資訊交換標準程式碼。 用於表示字母數位字元的七位或八位程式碼。 它是資料處理系統和相關設備之間通信使用的標準程式碼。

ASME

美國機械工程師學會。

組合語言程式

一種將組合語言指令轉換為機器語言指令的程式。

組合語言

一種面向機器的語言，使用助記符來表示每個機器語言指令。每個 CPU 都有自己的特定組合語言。

ASTM

美國資料試驗協會。

非對稱電位

當玻璃膜兩側有相同溶液時產生的電位。也是用於比較 pH7 緩衝液中玻璃電極電位時使用的電位。

非同步

一種通信方法，數據在準備好後發送，不參考定時鐘，而不是等待接收方發出準備接收的訊號後再發送。

ATC

自動溫度補償。

自動歸零

在零電壓輸入時自動進行內部偏移和/或漂移校正。

自動重置

1. 限制控制器的一個特性，當受控溫度回到設定的限制帶內時自動重置控制器。 2. PID 控制器上的積分功能，根據設定點調整比例頻寬，以補償電路中的偏移，即在系統穩定後將受控溫度調整到設定點。

AWG

美國線規。

旋轉軸（自旋軸）

物體旋轉的直線。

背景雜訊

量測系統中來自所有干擾源的總本底雜訊，與資料訊號的存在無關。

備份

在發生故障或資料丟失時可以作為替代方案使用的系統、設備、檔案或設施。

頻寬

設定點周圍的對稱區域，在這裡進行比例控制。

基本運輸參考

美國政府測試規範 MIL-STD-810D 的基本運輸部分，方法 514.3，第 I-3.2.1 段，第514.3-5頁。 基本運輸參攷定義了通過陸路、海路或空路作為固定貨物運輸設備時的測試設定檔。 測試水准基於陸路運輸的應力水准，因為陸路運輸的應力水准高於空氣或海洋運輸環境中的應力。

Basic

一種在達特茅斯學院（Dartmouth College）設計的高級程式設計語言，用作學習工具。 初學者通用符號指令程式碼（Beginner’s All-purpose Symbolic Instruction Code）的縮寫。

波特

表示資料傳輸速度的組織，等於每秒的位數（或訊號事件數）；300 波特=300 比特/秒。

緩衝 BCD（二進位編碼十進位）

帶有輸出驅動器的二進位編碼十進位輸出，以新增線路驅動能力。

並行 BCD

一種數位數據輸出格式，其中每個十進位數位由四條線上的二進位訊號表示，所有數位同時顯示。線路總數為十進位數位數的 4 倍。

串列 BCD

一種數位資料輸出格式，其中每個十進位數位由四條線上的二進位訊號表示，最多依次顯示五個十進位數位。線路總數為四條資料線加每個數位的一條選通線。

三態 BCD

並行 BCD 的一種實現，具有 0、1 和高阻抗輸出狀態。當並行連接應用中 BCD 輸出未定址時使用高阻抗狀態。

軸承

支撐軸頸的部件，軸頸在其中旋轉。

拍頻

拍頻是由兩個或多個正弦訊號相加和相减產生的週期性振動。例如，兩臺渦輪飛機發動機的轉速幾乎相同但不完全相同時，會生成四種頻率：（f1）渦輪一的旋轉頻率，（f2）渦輪二的旋轉頻率，（f1 + f2）渦輪一和渦輪二的旋轉頻率之和，以及（f1 - f2）渦輪一和渦輪二的頻率差或“拍頻”。兩個頻率的差值是較低頻率，並且在這種情況下感受到的是一種“拍”或“顫音”。

氧化鈹

氧化鈹（BeO），是一種高溫礦物絕緣材料；粉末形態時有毒。

最佳擬合直線（BFSL）

包含所有輸出與壓力值的兩條平行直線之間的中間線。

貝塔比率

管道收縮直徑與未收縮管道直徑的比值。

偏置電流

面板儀錶產生並疊加在訊號上的非常低的直流電流。此電流可能在非常高的源阻抗上引入可量測的偏移。

二進位編碼十進位（BCD）

用四比特二進位數表示十進位數（基數 10，0 到 9）。

二進位

指二進位計數系統，允許的數位只有 0 和 1。與僅有兩種可能值或狀態的情况有關。

BIOS

基本輸入/輸出系統。用於告訴 CPU 如何與電腦的其餘部分通信的命令。

雙極性

面板儀錶顯示正負兩種讀數的能力。

位

二進位數位的縮寫。電腦資訊的最小組織，它是二進位的 0 或 1。

黑體

在給定溫度下輻射最大能量並吸收所有入射能量的理論物體。 黑體不一定是黑色的。 （黑體一詞的由來是黑色定義為完全吸收光能量的顏色）。

BNC

一種快速斷開電力連接器，用於互連和/或終接同軸電纜。

沸點

物質從液態轉變為氣態的溫度；通常指海平面上水的沸點，即 100°C（212°F）。

BPS

每秒比特數。

擊穿電壓額定值

在不會在特定電流值以上產生電弧或導電的情况下，可以施加在換能器絕緣部分的直流或交流電壓。

橋接電阻

見“輸入阻抗”和“輸出阻抗”。

BTU

英國熱量組織。在最大密度下將一磅水加熱 1 華氏度所需的熱能。1 BTU 等於 0.293 瓦時或 252 卡路里。一千瓦時相當於 3412 BTU。

緩衝容量（B）

溶液在加入強酸或強鹼時抵抗 pH 變化的能力的度量。

緩衝

1. 從一臺設備向另一臺設備傳輸數據時用於補償速度差异的資料存儲區域。通常指為 I/O 操作保留的區域，數據從這裡讀取或寫入。

2. 任何物質或物質的組合，當其溶解在水中時，產生的溶液能够抵抗加入酸或堿後其氫離子濃度的變化。

球部（玻璃液體溫度計）

玻璃液體溫度計尖端儲存液體的區域。

老化測試

一種長期篩選測試（振動、溫度或組合測試），通過加速時間、功率和溫度關係，類比設備的實際或最壞情况操作，有效地避免初期故障。

爆破壓力

在不引起洩漏的情况下施加在換能器感應元件或外殼上的最大壓力。

爆破比例

時間比例控制器上的一種快速循環輸出形式（通常可調節為 2 到 4 秒），與固態繼電器配合使用，通過最小化熱應力來延長加熱器壽命。

母線

用於在設備或元器件之間傳輸訊號的並行線。電腦通常通過其母線結構來進行描述（如 S-100，IBM PC）。
字節：字符的二進位標記法。八位。

卡倫德-範杜森（Calender-van Dusen）方程式

定義任何純金屬的電阻-溫度值的方程式，其形式 RT = RO（1+AT+BT²）適用於冰點（0°C）和銻的凝固點（630.7°C）之間的值，而形式 RT = RO[1+AT+BT²+C（T-100）T²] 適用於氧點（–183.0°C）和冰點（0°C）之間的值。

校準

調整儀器或編制偏差圖，使其讀數與所量測的實際值相關聯的過程。

卡路里

在 15°C 時將1克水的溫度升高 1°C 所需的熱能量。

陽離子

帶正電荷的離子（Na+，H+）。

氣蝕

由於壓力下降而非溫度升高引起的液體沸騰現象。

攝氏度（百分制）

一種溫度標度，定義為海平面上水的冰點為 0°C，沸點為 100°C。

重心（質心）

物體的重心是指在均勻重力場中，物體中所有組成顆粒的重量合力在所有方向上通過的那個點。

向心力

作用於沿圓路徑移動的物體上的力，該力朝向旋轉中心。

陶瓷絕緣

用於絕緣一對熱電偶線的高溫金屬氧化物組合物，最常見的有氧化鋁（Al2O3）、氧化鈹（BeO）和氧化鎂（MgO）。 它們的應用取決於溫度和熱電偶的類型。鉑合金熱電偶需要高純度的氧化鋁。陶瓷絕緣體有單孔和多孔管或珠粒可供選擇。 

陶瓷

用作壓電加速度計中的感測單元的多晶鐵電材料。有許多不同等級的材料，可以形成各種配置以滿足不同的設計要求。

CFM

每分鐘立方英尺，表示液體或氣體的體積流量。

字元

用於表示資料的字母、數位或其他符號。一連串的字元稱為字串。

電荷靈敏度

對於以電荷靈敏度為標準的加速度計，輸出電壓（V）與電荷（Q）除以並聯電容（C）的值成正比。 這類加速度計的特點是高輸出阻抗。 靈敏度用電荷表示; 每單位加速度（g）的皮庫倫。
抖動：由於控制器頻寬不足導致繼電器在控制過程中快速循環開啟和關閉。

CHROMEGA®

組成 K 型和 E 型熱電偶的正極的鉻鎳合金（OMEGA ENGINEERING 公司的註冊商標）。 

清除

將設備恢復到規定的初始狀態，通常為零狀態。

削波

用於描述當輸出信號因放大器、ADC 或其他設備的全量程而受到某種方式的限制時出現的現象。 發生這種情況時，信號在峰值處被削平，信號趨於方波形狀，並引入高頻分量。削波可能是硬性限制，如信號嚴格限制在某一水準; 也可能是軟性限制，在這種情況下，削波信號在某種減少的增益下繼續跟隨輸入。 

時鐘

用於生成週期性信號以完成同步的設備。

控制精度

與預期系統設定點相比的總溫度變化。表示為“控制精度”為 ±2°C 或系統帶寬為 4°C，也稱為偏差幅度。

CMR（共模抑制） 

面板儀錶消除信號和地之間的交流或直流雜訊影響的能力。直流到 60 Hz 的範圍內通常以分貝表示。 一種 CMR 類型在SIG LO 和 PWR GND 之間指定。 在差分儀錶中，另一種指定類型在 SIG LO 和 ANA GND（METER GND）之間指定。

CMV（共模電壓）

在信號和地之間可耐受的交流或直流電壓。 一種 CMV 類型在 SIG LO 和 PWR GND 之間指定。在差分儀錶中，第二種CMV 類型在 SIG HI 或 LO 和 ANA GND（METER GND）之間指定。

相幹函數

計算得出的頻域函數，用於顯示系統輸入和輸出之間線性、無雜訊關係的程度。相幹函數的值在 0 和 1 之間，0 表示輸入和輸出之間沒有因果關係。1 表示輸入和輸出之間存在線性無雜訊頻率回應。

顏色編碼

ANSI 規定，熱電偶導線負極的顏色始終為紅色。基本金屬熱電偶的顏色編碼為：K 型為黃色，J 型為黑色，E 型為紫色，T 型為藍色。 

共模抑制比

儀器抗其輸入端與地之間的共模電壓干擾的能力。通常用分貝（dB）表示。 

共模

溫度控制器用於控制溫度的輸出形式或控制動作類型，例如開/關、時間比例、PID。 

通訊

資料處理設備和相關外設之間的資料發送和接收。

補償連接器

用熱電偶合金製成的連接器，用於連接熱電偶探頭和導線。

補償合金

用於將熱電偶連接到儀器的合金。 選擇的這些合金具有類似於熱電偶合金的熱電特性（但僅在非常有限的溫度範圍內）。

補償環路

對 RTD 元件的導線電阻補償，其中一段額外的導線從儀器連接到 RTD 再返回儀器，不與 RTD 連接。 

補償

添加特定材料或設備以抵消已知誤差。

編譯器

將高級語言（如 Basic）轉換成機器語言的程式。 

複數函數

由以下表達式給出的任何數學定義的關係：

y（x）=a（x）+ib（x）

其中 x=實變數

a（x）=y（x）的實部

b（x）=y（x）的虛部

復數函數通常通過其幅度和相位表示。

複合波

若干正弦波相加形成的週期性波的結果形式。這些波可以在頻域中進行分析，以便確定其組成部分。

電導

溶液傳導電流的能力的度量。（見“等效電導率”）。 

傳導

通過導體傳遞電能或熱量。

置信水準

測量量真實值的範圍（有指定的不確定度值，通常以百分比表示）。

一致性誤差

對於熱電偶和 RTD，實際讀數與發佈的表中顯示的特定電壓輸入下的溫度之間的差異。 

連接頭

連接到熱電偶末端的外殼，可以是鑄鐵、鋁或塑膠材質，在其中建立電氣連接。

康銅

一種用於 E 型、J 型和 T 型熱電偶的負極的銅鎳合金。 

連續光譜

以非週期性數據為特徵的頻譜。 頻譜在頻域中是連續的，並以無限數量的頻率成分為特徵。

控制字元

一種字元，出現在特定上下文中時會啟動、修改或停止影響數據記錄、處理、傳輸或解釋的操作。

控制模式

溫度控制器用於控制溫度的輸出形式或控制動作類型，例如開/關、時間比例、PID。

控制點

系統要保持的溫度。

對流

1. 由於密度變化和重力作用，在非均勻溫度下流體中發生的循環運動。

2. 通過這種流體自動循環傳遞熱量的過程。

科里奧利力（Coriolis force）

在旋轉平面中沿徑向向外移動的品質上由向心力產生的結果。

校正（平衡）平面

垂直於轉子軸軸線的平面，用於校正不平衡。

庫侖靈敏度

庫侖靈敏度

庫侖

電荷量的測量單位，通常以皮庫侖（10-12 庫侖）表示。

平衡重

為了在期望位置上減少計算的不平衡而添加到物體上的重量。

計數

雙斜率 A/D 轉換器計數的時間間隔數量，並在添加小數點之前顯示為面板儀錶的讀數。

CPS

週期/秒; 每秒週期性事件的頻率或數量，以赫茲（Hz）表示。

CPU

中央處理器，計算機的一部分，包含控制和執行計算機指令的電路。

臨界阻尼

臨界阻尼是指給定系統能夠響應階躍函數而不出現超調的最小阻尼量。

臨界速度

轉子或旋轉元件的轉速，在該轉速下系統發生共振。在該轉速下，至少激發軸的一個「臨界」或固有頻率。

低溫測量

在極低溫度下進行的溫度測量，即低於 –200°C。

CSA

加拿大標準局。

居裡點

通常具有磁性的材料經過磁性轉變而變成非磁性的溫度。

電流比例

溫度控制器的一種輸出形式，提供與所需控制量成比例的電流。 通常是 4 到 20 毫安電流比例帶。

電流

電流的流動速率。安培（A）單位定義為 1安培 = 每秒 1 庫侖。

曲線擬合

計算函數係數以在該函數內確定近似給定數據集值的過程。 該近似稱為“擬合”。使用數學函數（例如最小二乘回歸）來判斷擬合的準確性。

週期時間

控制器完成一個開/關週期所需的時間，通常以秒為單位。

阻尼

通過能量耗散來減少振動運動。 類型包括粘性、庫侖和固體阻尼。

資料庫

以組織有序的方式存儲的大量數據。 資料庫管理系統（DBMS）是允許訪問資訊的程式。

dB（分貝）

兩個電壓比的以 10 為底的對數的 20 倍。 每增加 20dB，電壓比增加 10 倍; 每增加 10dB，電壓比增加 3.162 倍。 例如，120dB 的 CMR 提供的電壓雜訊抑制比為 1000000/1。70dB 的 NMR提供的電壓雜訊抑制比為 3162/1。

DC

直流電;僅沿一個方向流動且值基本恆定的電流。

死區

1. 對於圖表記錄：引起筆位置偏移所需的最小輸入信號變化。

2. 對於溫度控制器：在溫度上升時關閉加熱並在溫度下降時開啟加熱的溫度帶，以度表示。 在此區域內不進行加熱（或冷卻）。

死體積

換能器在室溫和環境氣壓下的壓力端口體積。

調試

查找並糾正程式中的錯誤。

德拜-休克爾（Debye-H ̧ckel）方程

用於將活度係數（fi）與離子強度（見“活度係數”）相關聯的方程：其中 I 是離子強度，A 和 B 是溫度依賴常數（見表A.5），Zi 是離子的價態（i），Â 是以埃為單位的離子尺寸參數。

十進位

使用字元 0 到 9 來表示值的十進位計數系統。

預設值

在未指定時，操作期間假定的值或選項。

度

溫標的增量值，在攝氏溫標中，冰點和沸點之間有 100 攝氏度，而在華氏溫標中，冰點和沸點之間有 180 華氏度。

密度

單位體積的物質品質。 例如：克/立方釐米或磅/立方英尺。

微分（Derivative）

微分功能感應系統溫度上升或下降的速率，並自動調整控制器的週期時間以最小化超調或欠調。

偏差

受控變數的值與其被控制目標值之間的差異。

隔膜

由膜片組成的感測元件，膜片會因為施加在其上的壓力差而發生形變。

介電常數

與在均勻介質中相隔一段距離的兩個相反電荷之間的吸引力有關。

差分輸入

一種信號輸入電路，其中 SIG LO 和 SIG HI 在電氣上相對於 ANALOG GND（METER GND，通常連接到 DIG GND）是浮動的。 它允許測量連接到同一地的兩個信號之間的電壓差，並提供卓越的共模雜訊抑制。

差壓

在初級設備中位於兩個不同位置的相同高度的兩個相同測壓點之間的靜壓差。

差分

對於開/關式控制器，指的是控制器關閉加熱和重新開啟加熱之間的溫度差。以度數表示。 

數位

面板儀錶顯示範圍的度量。按照慣例，完整數位可以取 0 到 9 之間的任何值，半數字顯示 1 並在 2 時過載，四分之三數字顯示到 3 的數位並在 4時過載，以此類推。例如，顯示範圍為 ±3999 計數的儀錶稱為 3-3/4 數位儀錶。

數字輸出

以一系列離散量的形式表示輸入大小的輸出信號。

數-模轉換器（D/A 或 DAC）

將數位值轉換為類比信號電平的設備或電路。

DIN（德國工業標準）

一套全世界公認的德國標準。1/8 DIN 面板儀錶標準規定了 96x48mm 的外部邊框尺寸和 92x45mm 的面板開口尺寸。

DIN 43760

定義 100 歐姆鉑 RTD 特性的標準，其電阻與溫度曲線由 α=0.00385 歐姆/度規定。

放電時間常數

感測器或系統的輸出電壓在回應零上升時間階躍函數輸入時，放電至其原始值的 37% 所需的時間。此參數決定低頻回應。

磁碟作業系統（DOS）

用於控制向磁碟傳輸和從磁碟傳輸資訊的程式，例如 MS DOS。

位移

測量點從其靜止位置移動的距離。 峰到峰位移是振動點在其正負極限之間的總運動距離。 測量單位以英寸或毫英寸表示。

耗散常數

熱敏電阻的比值，它將內部功率耗散的變化與體溫度的相應變化相關聯。

解離常數（K）

溶液中物質解離程度的量化表達值。K 值越小，溶液中物質的解離越少。此值隨溫度、離子強度和溶劑的性質而變化。

DMA

直接記憶體訪問; IBM PC 的一種高速資料存儲模式。

雙精度

需要兩個電腦字來表示數位的精度等級。數位以 17 位的精度存儲，並最多以 16 位打印。

漂移

由於多個因素（包括環境溫度變化、時間和線路電壓等）導致的讀數或設定值在長時間內的變化。

下垂

時間比例控制器中常見的一種現象。 它指的是由於控制器的時間比例作用，系統溫度實際穩定點與設定點之間的溫度差。

雙元件感測器

包含兩個獨立感測元件的感測器元件。

雙斜率 A/D 轉換器

一種模數轉換器，在特定時間內對信號進行積分，然後對參考電壓的時間間隔進行計數，以將積分信號恢復為零。這種轉換器以低成本提供高解析度、優秀的標準模式雜訊抑制，而且對電路元件的依賴性最小。

雙絞線

一對彼此絕緣的導線，外部有絕緣護套包裹內絕緣對。

雙工

指同時在兩個方向上進行獨立數據通信傳輸。 同“全雙工”。

佔空比

完成一個開/關週期的總時間。通常指溫度控制器的開/關周期時間。

動態（雙平面）平衡機

一種離心平衡機，提供進行雙平面平衡所需的資訊。

動態校準

輸入在特定時間段內不斷變化，並根據時間推移記錄輸出的校準過程。

動態壓力

由速度增加引起的靜壓到滯止壓的壓差。動態壓力隨著速度的平方增加。

動態不平衡

中心主軸線與軸線不重合的狀態。

回聲

將接收到的資料反射給發送者。例如，按下鍵盤上的鍵通常會作為字元顯示在螢幕上。

電氣干擾

信號線上的電氣雜訊，干擾所需的信息信號。

電極電位（E）

將電極浸入到溶液中時，電極和溶液之間的電位差。

電極

見“等電位點”。

電解質

任何在溶液中能導電的物質。常見的電解質有酸、堿和鹽。

電動勢（emf）

電池中兩個電極之間的電位差。當沒有電流通過電池時，電池的電動勢是測得的電池電壓。可以通過具有高輸入阻抗的 pH 計測量。

電子工業協會（EIA）

一個專門研究介面設備的電氣和功能特性的標準組織。

EMF

電動勢。電位能的上升。主要單位是伏特。

EMI

電磁干擾。

發射率

物體發射的能量與同溫度下黑體發射的能量之比。物體的發射率取決於其材料和表面紋理; 拋光金屬表面的發射率約為 0.2，而木塊的發射率約為 0.95。

終點（電位滴定）

滴定的表觀等當點，在此點上出現相對較大的電位變化。

終點

全量程校準曲線的終點。

吸熱

吸收熱量。當一個過程吸收熱量時，稱其為吸熱過程。

焓

物體的內能與其體積乘以壓力的乘積之和。

環境條件

換能器在運輸、儲存、搬運和操作過程中可能暴露在外的所有條件。

Eprom–可擦除可程式設計唯讀記憶體

PROM 可以通過紫外線或電流擦除。 

平衡常數

化學反應中在平衡時生成的物質的濃度（或活度）的乘積除以反應物濃度的乘積，每個濃度提高到化學方程中物質的係數的冪。

等電擴散（Equitransference）

電解質的正負離子在液體結點間不發生電荷分離的情況下等速擴散。

等效電導率（I）

電解質的等效電導率定義為，含有一個當量溶解物質的溶液體積在兩個相距 1 釐米的平行電極之間的電導率，並且該體積足夠大以包含所有溶液。 L 從不確定，而是根據比電導率（Ls）計算得出。如果 C 是溶液的濃度（以每升克當量表示），那麼每立方釐米的濃度為 C/1000，因此含有一個溶質當量的體積為 1000/C。

誤差帶

輸出與特定參考標準之間的允許偏差。通常以全量程的百分比表示。

誤差

換能器顯示的值與被測量的真實值之間的差異。通常以全量程輸出的百分比表示。

共晶溫度

合金混合物的最低可能熔點。

激勵

為了正常操作而施加到換能器上的外部電壓電流。

放熱

釋放熱量。當一個過程釋放熱量時，稱其為放熱過程。

膨脹係數

修正收縮流中兩個壓力測量區域之間的密度變化的修正係數。

防爆外殼

一種外殼，能夠承受內部氣體爆炸並防止由於火花、閃光或容器本身的爆炸而引起周圍氣體爆炸，並保持不會點燃周圍氣體的外部溫度。

裸露接頭

熱電偶探頭的一種結構形式，其熱端或測量接頭突出於護套材料之外，完全暴露在被測介質中。這種結構形式通常具有最快的回應時間。

華氏度

一種溫度刻度，海平面上水的冰點為 32 度，沸點為 212 度。

襯套

一種可壓縮的管狀配件，壓縮到壓縮配件內的探頭上，形成氣密密封。

現場平衡設備

用於對未安裝在平衡機上的組裝機械進行平衡操作的一種測量儀器。

視場

由從儀器的焦平面上延伸的角錐定義的空間體積。

檔

作為一個單元進行處理的一組相關記錄或數據。

填充溶液

用於使內部元件與膜或樣品相接觸的定義成分的溶液。封閉在 pH 玻璃泡中的溶液稱為內部填充溶液。這種溶液通常含有緩衝的氯化物溶液，以提供穩定的電位和指定的零電位點。圍繞參考電極內部並需要定期補充的溶液稱為參考填充溶液。它通過連接點使參考電極內部與樣品相接觸。

固件

存儲在 PROM 中的程式。

標誌

用於標識某種條件或事件的各類指示器; 例如，表示資料傳輸終止的字元。

軟盤

一種包含磁性介質的小型柔性磁碟，用於存儲數位資料以供以後檢索和使用。

流速

流體運動的實際速度或速度。

流動

液體或氣體在壓力或重力等力作用下的運動。

流量計

用於測量流動流體的流量或數量的設備。

FM 認證儀器

符合 Factory Mutual Research Corporation 制定的一組特定規範的儀器。

FM Factory Mutual Research Corporation

一個制定工業安全標準的組織。

強制振動

由施加的力引起的系統振動。穩態振動是週期性或隨機運動的恆定不變條件。

FORTRAN–公式翻譯語言

一種廣泛使用的高級程式設計語言，適用於可以用代數公式表達的問題。通常用於科學應用。

FPM

以每分鐘英尺為單位的流速。

FPS

以每秒英尺為單位的流速。

冰點

物質從液態變為固態的溫度。

頻率調製輸出

一種換能器輸出，以偏離中心頻率的偏差形式獲得，偏差與施加的激勵成比例。

振動頻率

在給定時間單位內發生的週期數。RPM-每分鐘轉數。CPM-每分鐘週期數。

頻率輸出

頻率形式的輸出，隨施加的輸入而變化。

自然頻率

完全組裝的換能器元件的自由（非強迫）振蕩頻率。

頻率

在指定時間段內事件發生的週期數。其倒數稱為週期。

全橋

使用四個有源元件或應變計的一種惠斯通（Wheatstone）電橋配置。

全量程輸出

最小輸出與最大輸出之間的代數差。

功能

三模式 PID 控制器。 一種具有積分和微分功能的時間比例控制器。 積分功能自動將系統溫度調整至設定溫度，以消除由於時間比例功能引起的溫度下降。

G

重力加速度力，等於 32.1739 英尺/秒² 或 386 英寸/秒²。

應變數

壓阻式應變計的電阻相對變化與長度相對變化的比率的量度。

標距

應變數發生的兩個點之間的距離。

表壓換能器

一種相對於環境壓力測量壓力的換能器。

表壓

絕對壓力減去當地大氣壓力。

增益

電路中使用的放大量。

檢流計

一種通過偏轉磁線圈測量小電流的儀器。

GPH

以每小時加侖計的體積流量。

GPM

以每分鐘加侖計的體積流量。

接地

1. 電位與周圍地球相同的電氣中性線。

2. 直流電源的負極。

2. 電氣系統的參考點。

接地接頭

熱電偶探頭的一種結構形式，其中熱端或測量接頭與護套材料電氣接觸，使護套和熱電偶具有相同的電位。

半橋

兩個有源元件或應變計。

半雙工

特定時刻單向數據通信; 兩個設備都可以發送和接收數據，但一次只能有一個發送或接收。

握手

一種基於狀態/資料信號的介面程序，確保有序的資料傳輸，與異步交換相對。

硬拷貝

永久形式（通常為列印輸出）而非臨時形式（如磁碟或顯示終端上的）的輸出。

硬體

與運算系統相關的電氣、機械和機電設備和部件，與固件或軟體相對。

頭損失

流量系統中的壓力損失，使用長度參數（如英寸水柱、英寸汞柱）測量。

頭壓力

以流體高度表示的壓力，P=yrg，其中 r=流體密度，y=流體柱高度。 以流體高度表示的壓力，r=yrg，其中 r 是流體密度，y=流體柱高度。 g=重力加速度。

散熱器

1. 熱力學：可以吸收熱能的物體。

2. 實際應用：用於散熱的帶散熱片的金屬裝置，用於散發安裝在其上的固態元件的熱量。

熱傳遞

熱能從高能體流向低能體的過程。傳遞方式有：導熱; 兩個物體接觸。對流; 導熱的一種形式，其中接觸的兩個物體為不同相態，例如固體和氣體。輻射：所有物體都發出紅外輻射。

熱處理

一種處理金屬的過程，通過加熱到特定溫度並以特定速度冷卻來改變金屬的屬性。

熱量

熱能，以卡路里或 BTU 為單位表示。

赫茲（Hz）

表示頻率的單位。與每秒週期數同義。

十六進位

指使用字元 0 到 9 和 A 到 F 表示值的十六進位計數系統。機器語言程式通常以十六進位表示法編寫。

保持

表保持是用於停止 A/D 過程並凍結顯示的外部輸入。 BCD 保持是用於凍結 BCD 輸出，同時允許 A/D 過程繼續操作的外部輸入。

胡克（Hooke）定律

定義通過應變數來測量機械應力的基礎。胡克線的梯度由相當於彈性模量 E（楊氏模量）的比率定義。

主機

多部件系統中的主要或控制計算機。

氫離子活度（aH+）

溶液中氫離子的活度。通過氫的活度係數（f H+）與氫離子濃度（CH+）相關聯。

滯後（電極記憶）

當電極系統返回到溶液中時，通常不會立即達到平衡。這種現象常見於暴露於其他影響（如溫度、光線或極化）的電極中。

滯後

當測量值首先以新增然後以减少的值接近時的輸出差异。在任何一個校準週期內以全量程的百分比表示。另見“死區”。

圖標

用圖形顯示的功能符號。電腦要執行的一種或多種功能的圖形表示。

ICP—集成電路壓電

有時用於描述帶內寘電子裝置的加速度計的術語。

阻抗

對電流流動的總阻力（電阻加反應）。

紅外線

電磁光譜中延伸到紅光以外的區域，從 760 納米到 1000 微米（106 納米）。它是用於非接觸式溫度測量的輻射形式。

初始不平衡

進行平衡前轉子中存在的任何類型的不平衡。

輸入阻抗

在換能器的激勵端子上量測的電阻。

輸入電阻（阻抗）

pH 計的輸入電阻是玻璃電極端子和參考電極端子之間的電阻。pH 量測電極鏈的電位始終受總電極電阻和輸入電阻之間的電壓分配影響。

絕緣接頭

見“未接地接頭”。

絕緣電阻

在室溫下施加特定直流電壓時，在換能器的兩個絕緣點之間量測的電阻。

積分

一種溫度控制形式。見“自動重置”第 2 條。

互換性誤差

使用兩個或多個探頭進行相同的量測時可能出現的測量誤差。 這是由不同探頭的特性差异導致的。

介面

兩個系統或設備相互連接並相互作用的方式。

內部參考電極（元件）

放置在玻璃電極內部的參考電極。

解譯器

一種系統程式，在運行時將高級語言程式的每條指令轉換為機器程式碼並執行，然後再執行下一條指令。

中斷

以可以恢復的方式停止一個過程。

本質安全

在正常或异常條件下不會產生任何火花或熱效應，不會點燃特定氣體混合物的儀器。

離子遷移率

定義類似於非電解質粒子的遷移率，即在組織電力影響下離子在特定溶劑中獲得的速度。

離子強度

溶液中離子的重量濃度，計算方法如下：用溶液中每種離子的濃度（C）乘以相應離子的電荷（Z）的平方，對溶液中的所有離子求和，然後除以 2：離子強度 –1/2 _ Z²C。

IPTS-48

1948 年國際實用溫標。1948 年第九届國際計量大會指定的溫度測量固定點。

IPTS-68

1968 年國際實用溫標。1968 年國際計量大會規定的溫度測量固定點。

ISA

美國儀器學會。

隔離

通過使用彈性隔離資料减少系統響應外力的能力。

等電位點

不受溫度變化影響的電位。它是給定電極對的 dE/dt 為零時的 pH 值。通常，對於玻璃電極和 SCE 參考，當浸入 pH7 緩衝液時，大約獲得此電位。

等溫

溫度恒定的一個過程或區域。

焦耳

熱能的基本組織。

軸頸

轉子的一部分，與軸承接觸或由軸承支撐並在其中旋轉。

接頭

熱電偶中兩種不同金屬連接的點。

K

指存儲容量時為 2 的 10 次方（十進位表示為 1024）。

開爾文

符號 K。基於攝氏溫標的絕對或熱力學溫標組織，以冰點和沸點之間 100 個組織為基準。0°C=273.15K（開爾文溫標不使用度（°）符號）。

千瓦（kw）

等於 1000 瓦。

千瓦時（kwh）

1000 瓦時。千伏安（kva）：1000 伏安。

動能

與運動中的質量相關的能量，例如 1/2 rV²，其中 r 是運動質量的密度，V 是其速度。

KVA

千伏安（1000 伏安）。

滯後

1. 訊號輸出與接收訊號的儀器響應之間的時間延遲。

2. 兩個波形之間的時間關係，其中一個波的固定參考點出現在參考波的同一點之後。

層流

流體的流動，其粘性力比慣性力更顯著，通常出現在雷諾數低於 2000 時。

大規模集成（LSI）

在單個晶片上結合約 1000 到 10000 個電路。LSI 電路的典型例子包括存儲晶片和微處理器。

潛熱

以每磅 BTU 數表示。將一磅沸水轉換為一磅蒸汽所需的（吸收的）熱量。

洩漏率

允許或確定流體通過密封洩漏的最大速率。流體的類型，差壓誤差限：ANSI 規範 MC-96.1（1975）定義的熱電偶導線熱電響應的容差帶，以度數或百分比表示。

最小二乘線

殘差（偏差）的平方和最小的直線。

壽命週期

換能器可以承受並且仍然保持在指定公差範圍內的最小壓力週期數。

誤差極限

ANSI 規範 MC-96.1（1975）定義的熱電偶導線的熱電響應的容差帶，以度數或百分比表示。

線性度

校準曲線與指定直線的接近程度。 線性度以任何一個校準週期中指定直線上任何校準點的最大偏差表示。

液接電位

存在於液體-液體邊界之間的電位差。此電位的符號和大小取決於液體的成分和使用的接頭類型。

負載阻抗

由相關外部電路呈現給換能器輸出端子的阻抗。

負載

電力電子的需求，用功率（瓦特）、電流（安培）或電阻（歐姆）表示。

對數刻度

以十的幂顯示數據的方法，在獲得最大範圍的同時保持刻度低端的分辯率。

環路電阻

熱電偶電路的總電阻，由熱電偶導線電阻引起。 通常用於類比高溫計，典型的環路電阻要求為 10 歐姆。

LS-TTL 相容

對於數位輸入電路，輸入為 2.0 至 5.5 V，可以提供 20µA 的電流時將獲得邏輯 1，輸入為 0 至 0.8 V，可以吸收 400µA 的電流時，將獲得邏輯 0。 對於數位輸出信號，邏輯 1 表示為 2.4 至 5.5 V，電流提供能力至少為 400µA； 邏輯 0 表示為 0 至 0.6 V，電流吸收能力至少為 16 mA。LS 代表低功耗肖特基。

LS-TTL unit load

A load with LS-TTL voltage levels, which will draw 20 µA for a logic 1 and -400 µA for a logic 0.

LSD (least-significant digit)

The rightmost active (non-dummy) digit of the display.

Mega; one million

When referring to memory capacity, two to the twentieth power (1,048,576 in decimal notation).

Machine language

Instructions that are written in binary form that a computer can execute directly. Also called object code and object language.

Mandrel (balancing arbor)

An accurately machined shaft on which work is mounted for balancing.

Manual reset (adjustment)

The adjustment on a proportioning controller which shifts the proportioning band in relationship to the set point to eliminate droop or offset errors.

Manual reset (switch)

The switch in a limit controller that manually resets the controller after the limit has been exceeded.

Mass flow rate

Volumetric flowrate times density, i.e. pounds per hour or kilograms per minute.

Mass storage

A device like a disk or magtape that can store large amounts of data readily accessible to the central processing unit.

Maximum elongation

The strain value where a deviation of more than ±5% occurs with respect to the mean characteristic (diagram of resistance change vs strain).

Maximum excitation

The maximum value of excitation voltage or current that can be applied to the transducer at room conditions without causing damage or performance degradation beyond specified tolerances.

Maximum operating temperature

The maximum temperature at which an instrument or sensor can be safely operated.

Maximum power rating

The maximum power in watts that a device can safely handle.

Mean ionic activity coefficient

See activity coefficient.

Mean temperature

The average of the maximum and minimum temperature of a processequilibrium.

Measurand

A physical quantity, property, or condition which is measured.

Measuring junction

The thermocouple junction referred to as the hot junction that is used to measure an unknown temperature.

Mechanical hysteresis

The difference of the indication with increasing and decreasing strain loading, at identical strain values of the specimen.

Medium effect (f m)

For solvents other than water the medium effect is the activity coefficient related to the standard state in water at zero concentration. It reflects differences in the electrostatic and chemical interactions of the ions with the molecules of various solvents. Solvation is the most significant interaction.

Melting point

The temperature at which a substance transforms from a solid phase to a liquid phase.

Membrane

The pH-sensitive glass bulb is the membrane across which the potential difference due to the formation of double layers with ion-exchange properties on the two swollen glass surfaces is developed. The membrane makes contact with and separates the internal element and filling solution from the sample solution.

Method of correction

A procedure whereby the mass distribution of a rotor is adjusted to reduce unbalance, or vibration due to unbalance, to an acceptable value. Corrections are usually made by adding material to, or removing it from, the rotor.

Mica

A transparent mineral used as window material in high-temperature ovens.

Microamp

One millionth of an ampere, 10-6 amps, µA.

Microcomputer

A computer which is physically small. It can fit on top of or under a desk; based on LSI circuitry, computers of this type are now available with much of the power currently associated with minicomputer systems.

Micron

One millionth of a meter, 10-6 meters.

Microvolt

One millionth of a volt, 10-6 volts.

Mil

One thousandth of an inch (.001″).

Milliamp

One thousandth of an amp, 10-3 amps, symbol mA.

Millimeter

One thousandth of a meter, symbol mm.

Millivolt

Unit of electromotive force. It is the difference in potential required to make a current of 1 millampere flow through a resistance of 1 ohm; one thousandth of a volt, symbol mV.

Mineral-insulated thermocouple

A type of thermocouple cable which has an outer metal sheath and mineral (magnesium oxide) insulation inside separating a pair of thermocouple wires from themselves and from the outer sheath. This cable is usually drawn down to compact the mineral insulation and is available in diameters from .375 to .010 inches. It is ideally suited for high-temperature and severe-duty applications.

Minor scale division

On an analog scale, the smallest indicated division of units on the scale.

Modem: modulator/demodulator

A device that transforms digital signals into audio tones for transmission over telephone lines, and does the reverse for reception.

Molality

A measure of concentration expressed in mols per kilogram of solvent.

Monovalent ion

An ion with a single positive or negative charge (H+, C1-).

Motherboard

The pc board of a computer that contains the bus lines and edge connectors to accommodate other boards in the system. In a microcomputer, the motherboard contains the microprocessor and connectors for expansion boards.

Mounting error

The error resultant from installing the transducer, both electrical and mechanical.

MSD (most-significant digit)

The leftmost digit of the display.

Mueller bridge

A high-accuracy bridge configuration used to measure three-wire RTD thermometers.

Multiplex

A technique which allows different input (or output) signals to use the same lines at different times, controlled by an external signal. Multiplexing is used to save on wiring and I/O ports.

N/C (no connection)

A connector point for which there is no internal connection.

NBS

National Bureau of Standards.

NEC

National Electric Codes.

Negative temperature coefficient

A decrease in resistance with an increase in temperature.

NEMA-4

A standard from the National Electrical Manufacturers Association, which defines enclosures intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose-directed water.

NEMA-7

A standard from the National Electrical Manufacturers Association, which defines explosion-proof enclosures for use in locations classified as Class I, Groups A, B, C or D, as specified in the National Electrical Code.

NEMA-12

A standard from the National Electrical Manufacturers Association, which defines enclosures with protection against dirt, dust, splashes by non-corrosive liquids, and salt spray.

NEMA-size case

An older US case standard for panel meters, which requires a panel cutout of 3.93 x 1.69 inches.

Nernst equation

A mathematical description of electrode behavior: E is the total potential, in millivolts, developed between the sensing and reference electrodes; Ex varies with the choice of electrodes, temperature, and pressure: 2.3RT/nF is the Nernst factor (R and F are constants, n is the charge on the ion, including sign, T is the temperature in degrees Kelvin), and ai is the activity of the ion to which the electrode is responding.

Nernst factor (s, slope)

The term 2.3RT/nF is the Nernst equation, which is equal (at T = 25°C) to 59.16 mV when n = 1 and 29.58 mV when n – 2, and which includes the sign of the charge on the ion in the term n. The Nerst factor varies with temperature.

Network

A group of computers that are connected to each other by communications lines to share information and resources.

Nibble

One half of a byte.

Nicrosil/Nisil

A nickel chrome/nickel silicone thermal alloy used to measure high temperatures. Inconsistencies in thermoelectric voltages exist in these alloys with respect to the wire guage.

NMR (normal-mode rejection)

The ability of a panel meter to filter out noise superimposed on the signal and applied across the SIG HI to SIG LO input terminals. Normally expressed in dB at 50/60 Hz.

Noise

An unwanted electrical interference on the signal wires.

Normal (axial) stress

The force per unit area on a given plane within a body a = F/A.

Normal hydrogen electrode

A reversible hydrogen electrode (Pt) in contact with hydrogen gas at 1 atmosphere partial pressure and immersed in a solution containing hydrogen ions at unit activity.

Normal-mode rejection ratio

The ability of an instrument to reject interference usually of line frequency (50-60 Hz) across its input terminals.

NPT

National Pipe Thread.

Null

A condition, such as balance, which results in a minimum absolute value of output.

O.D.

Outside diameter.

Octal

Pertaining to a base 8 number system.

Offset

The difference in temperature between the set point and the actual process temperature. Also, referred to as droop.

ofhc

Oxygen-free high-conductivity copper. The industrial designation of the pure copper used in a Type T thermocouple.

Ohmeter

An instrument used to measure electrical resistance.

On/off controller

A controller whose action is fully on or fully off.

Open circuit

The lack of electrical contact in any part of the measuring circuit. An open circuit is usually characterized by rapid large jumps in displayed potential, followed by an off-scale reading.

Operating system

A collection of programs that controls the overall operation of a computer and performs such tasks as assigning places in memory to programs and data, processing interrupts, scheduling jobs and controlling the overall input/output of the system.

Operational pH

The determination of sample pH by relating to pH measurements in a primary standard solution. This relationship assumes that electrode errors such as sensitivity and changes in asymmetry potential can be disregarded or compensated for, provided the liquid junction potential remains constant between standard and sample.

Optical isolation

Two networks which are connected only through an LED transmitter and photoelectric receiver with no electrical continuity between the two networks.

Outboard rotor

A two-journal rotor which has its center of gravity between the journals.

Output impedance

The resistance as measured on the output terminals of a pressure transducer.

Output noise

The RMS, peak-to-peak (as specified) ac component of a transducer’s dc output in the absence of a measurand variation.

Output

The electrical signal which is produced by an applied input to the transducer.

Overshoot

The number of degrees that a process exceeds the set point temperature when coming up to the set point temperature.

Parallax

An optical illusion which occurs in analog meters and causes reading errors. It occurs when the viewing eye is not in the same plane, perpendicular to the meter face, as the indicating needle.

Parallel transmission

Sending all data bits simultaneously. Commonly used for communications between computers and printer devices.

Parity

A technique for testing transmitting data. Typically, a binary digit is added to the data to make the sum of all the digits of the binary data either always even (even parity) or always odd (odd parity).

Peltier effect

When a current flows through a thermocouple junction, heat will either be absorbed or evolved depending on the direction of current flow. This effect is independent of joule I2 R heating.

Perfectly balanced rotor

A rotor is perfectly balanced when its mass distribution is such that it transmits no vibratory force or motion to its bearings as a result of centrifugal forces.

Peripheral

A device that is external to the CPU and main memory, i.e., printer, modem or terminal, but is connected by the appropriate electrical connections.
pH Junctions: The Junction of a reference electrode or combination electrode is a permeable membrane through which the fill solution escapes (called the liquid junction).

pH(S) (standard pH scale)

The conventional standard pH scale established on the basis that an individual ionic activity coefficient can be calculated from the Debye-H¸ckel law for primary buffers.

Phase difference

The time expressed in degrees between the same reference point on two periodic waveforms.

Phase proportioning

A form of temperature control where the power supplied to the process is controlled by limiting the phase angle of the line voltage.

Phase

A time based relationship between a periodic function and a reference. In electricity, it is expressed in angular degrees to describe the voltage or current relationship of two alternating waveforms.

PID – proportional, integral, derivative

A three mode control action where the controller has time proportioning, integral (auto reset) and derivative rate action.

Piezoelectric accelerometer

A transducer that produces an electrical charge in direct proportion to the vibratory acceleration.

Piezoresistance

Resistance that changes with stress.

Pixel – picture element

Definable locations on a display screen that are used to form images on the screen. For graphic displays, screens with more pixels provide higher resolution.

Plane separation

Of a balancing machine, is the operation of reducing the correction plane interference ratio for a particular rotor.

Platinel

A non-standard, high temperature platinum thermocouple alloy whose thermoelectric voltage nearly matches a Type K thermocouple (Trademark of Englehard Industries).

Platinum 6% rhodium

The platinum-rhodium alloy used as the negative wire in conjunction with platinum-30% rhodium to form a Type B thermocouple.

Platinum 10% rhodium

The platinum-rhodium alloy used as the positive wire in conjunction with pure platinum to form a Type S thermocouple.

Platinum 13% rhodium

The platinum-rhodium alloy used as the positive wire in conjunction with pure platinum to form a Type R thermocouple.

Platinum 30% rhodium

The platinum-rhodium alloy used as the positive wire in conjunction with platinum 6% rhodium to form a Type B thermocouple.

Platinum 67

To develop thermal emf tables for thermocouples, the National Bureau of Standards paired each thermocouple alloy against a pure platinum wire (designated Platinum 2 prior to 1973, and currently Platinum 67). The thermal emf’s of any alloy combination can be determined by summing the “vs. Pt-67” emf’s of the alloys, i.e., the emf table for a Type K thermocouple is derived from the Chromel vs. Pt-67 and the Alumel vs. Pt-67 values.

Platinum

A noble metal which in its pure form is the negative wire of Type R and Type S thermocouples.

Poisson ratio

The ratio between the strain of expansion in the direction of force and the strain of contraction perpendicular to that force v = -Et/E1.

Polarity

In electricity, the quality of having two oppositely charged poles, one positive one negative.

Polarization

The inability of an electrode to reproduce a reading after a small electrical current has been passed through the membrane. Glass pH electrodes are especially prone to polarization errors caused by small currents flowing from the pH meter input circuit and from static electrical charges built up as the electrodes are removed from the sample solution, or when the electrodes are wiped.

Port

A signal input (access) or output point on a computer.

Positive temperature coefficient

An increase in resistance due to an increase in temperature.

Potential energy

Energy related to the position or height above a place to which fluid could possibly flow.

Potentiometer

1. A variable resistor often used to control a circuit.

2. A balancing bridge used to measure voltage.

Power supply

A separate unit or part of a circuit that supplies power to the rest of the circuit or to a system.

PPM

Abbreviation for “parts per million,” sometimes used to express temperature coefficients. For instance, 100 ppm is identical to 0.01%.

Primary device

Part of a flowmeter which is mounted internally or externally to the fluid conduit and produces a signal corresponding to the flowrate and from which the flow may be determined.

Primary standard (NBS)

The standard reference units and physical constants maintained by the National Bureau of Standards upon which all measurement units in the United States are based.

Primary standards

Aqueous pH buffer solutions established by the National Bureau of Standards within the 2.5 to 11.5 pH range of ionic strength less than 0.1 and which provide stable liquid junction potential and uniformity of electrode sensitivity.

Principal axes

The axes of maximum and minimum normal stress.

Probe

A generic term that is used to describe many types of temperature sensors.

Process meter

A panel meter with sizeable zero and span adjustment capabilities, which can be scaled for readout in engineering units for signals such as 4 – 20mA, 10 – 50mA and 1 – 5V.

Program

A list of instructions that a computer follows to perform a task.

Prom – programmable read-only memory

A semiconductor memory whose contents cannot be changed by the computer after it has been programmed.

Proof pressure

The specified pressure which may be applied to the sensing element of a transducer without causing a permanent change in the output characteristics.

Proportioning band

A temperature band expressed in degrees within which a temperature controller’s time proportioning function is active.

Proportioning control mode

A time proportioning controller where the amount of time that the relay is energized is dependent upon the system’s temperature.

Proportioning control plus derivative function

A time proportioning controller with derivative function. The derivative function senses the rate at which a system’s temperature is either increasing or decreasing and adjusts the cycle time of the controller to minimize overshoot or undershoot.

Proportioning control plus integral

A two-mode controller with time proportioning and integral (auto reset) action. The integral function automatically adjusts the temperature at which a system has stabilized back to the setpoint temperature, thereby eliminating droop in the system.

Proportioning control with integral and derivative functions

Three mode PID controller. A time proportioning controller with integral and derivative functions. The integral function automatically adjusts the system temperature to the set point temperature to eliminate droop due to the time proportioning function. The derivative function senses the rate of rise or fall of the system temperature and automatically adjusts the cycle time of the controller to minimize overshoot or undershoot.

Protection head

An enclosure usually made out of metal at the end of a heater or probe where connections are made.

Protection tube

A metal or ceramic tube, closed at one end into which a temperature sensor is inserted. The tube protects the sensor from the medium into which it is inserted.

Protocol

A formal definition that describes how data is to be exchanged.

PSIA

Pounds per square inch absolute. Pressure referenced to a vacuum.

PSID

Pounds per square inch differential. Pressure difference between two points.

PSIG

Pound per square inch guage. Pressure referenced to ambient air pressure.

PSIS

Pounds per square inch standard. Pressure referenced to a standard atmosphere.

Pulse width modulation

An output in the form of duty cycle which varies as a function of the applied measurand.

Radiation

See infrared.

Random Access Memory (RAM)

Memory that can be both read and changed during computer operation. Unlike other semi-conductor memories, RAM is volatile-if power to the RAM is disrupted or lost, all the data stored is lost.

Range

Those values over which a transducer is intended to measure, specified by its upper and lower limits.

Rangeability

The ratio of the maximum flowrate to the minimum flowrate of a meter.

Rankine (°R)

An absolute temperature scale based upon the Fahrenheit scale with 180° between the ice point and boiling point of water. 459.67°R = 0°F.

Rate action

The derivative function of a temperature controller.

Rate time

The time interval over which the system temperature is sampled for the derivative function.

Ratiometric measurement

A measurement technique where an external signal is used to provide the voltage reference for the dual-slope A/D converter. The external signal can be derived from the voltage excitation applied to a bridge circuit or pick-off supply, thereby eliminating errors due to power supply fluctuations.

Read only Memory (ROM)

Memory that contains fixed data. The computer can read the data, but cannot change it in any way.

Real time

The time interval over which the system temperature is sampled for the derivative function.

Record

A collection of unrelated information that is treated as a single unit.

Recovery time

The length of time which it takes a transducer to return to normal after applying a proof pressure.

Redox potential

The potential developed by a metallic electrode when placed in a solution containing a species in two different oxidation states.

Reference junction

The cold junction in a thermocouple circuit which is held at a stable known temperature. The standard reference temperature is 0°C (32°F). However, other temperatures can be used.

Reference mark

Any diagnostic point or mark which can be used to relate a position during rotation of a part to its location when stopped.

Reference plane

Any plane perpendicular to the shaft axis to which an amount of unbalance is referred.

Refractory metal thermocouple

A class of thermocouples with melting points above 3600°F. The most common are made from tungsten and tungsten/rhenium alloys Types G and C. They can be used for measuring high temperatures up to 4000°F (2200°C) in non-oxidizing, inert, or vacuum environments.

Register

A storage device with a specific capacity, such as a bit, byte or word.

Relay (mechanical)

An electromechanical device that completes or interrupts a circuit by physically moving electrical contacts into contact with each other.

Relay (solid state)

A solid state switching device which completes or interrupts a circuit electrically with no moving parts.

Remote

Not hard-wired; communicating via switched lines, such as telephone lines. Usually refers to peripheral devices that are located a site away from the CPU.
Repeatability: The ability of a transducer to reproduce output readings when the same measurand value is applied to it consecutively, under the same conditions, and in the same direction. Repeatability is expressed as the maximum difference between output readings.

Reserved word

A word that has a defined function in the language, and cannot be used as a variable name.

Residual (final) unbalance

Residual unbalance is that unbalance of any kind that remains after balancing.

Resistance ratio characteristic

For thermistors, the ratio of the resistance of the thermistor at 25°C to the resistance at 125°C.

Resistance temperature characteristic

A relationship between a thermistor’s resistance and the temperature.

Resistance

The resistance to the flow of electric current measured in ohms (1/2) for a conductor. Resistance is function of diameter, resistivity (an intrinsic property of the material) and length.

Resolution

The smallest detectable increment of measurement. Resolution is usually limited by the number of bits used to quantize the input signal. For example, a 12-bit A/D can resolve to one part in 4096 (2 to the 12 power equals 4096).

Resonant frequency

The measurand frequency at which a transducer responds with maximum amplitude.

Response time (time constant)

The time required by a sensor to reach 63.2% of a step change in temperature under a specified set of conditions. Five time constants are required for the sensor to stabilize at 600 of the step change value.

Response time

The length of time required for the output of a transducer to rise to a specified percentage of its final value as a result of a step change of input.
Reynolds Number: The ratio of inertial and viscous forces in a fluid defined by the formula Re = rVD/µ, where: r = Density of fluid, µ = Viscosity in centipoise (CP), V = Velocity, and D = Inside diameter of pipe.

RFI

Radio frequency interference.

Rheostat

A variable resistor.

Rigid rotor

A rotor is considered rigid when it can be corrected in any two (arbitrarily selected) planes [see “Correction (Balancing)Plane”] and after that correction, its unbalance does not significantly exceed the balancing tolerances (relative to the shaft axis) at any speed up to maximum operating speed and when running under conditions which approximate closely to those of the final supporting system.

Rise time

The time required for a sensor or system to respond to an instantaneous step function, measured from the 10% to 90% points on the response waveforms.
Room Conditions: Ambient environmental conditions under which transducers must commonly operate.

Root Mean Square (RMS)

Square root of the mean of the square of the signal taken during one full cycle.

Rotor

A rotor is a rotating body whose journals are supported by bearings.

RTD

Resistance temperature detector.

Salt bridge

The salt bridge of a reference electrode is that part of the electrode which contains the filling solution to establish the electrolytic connection between reference internal cell and the test solution. Auxiliary Salt Bridge: A glass tube open at one end to receive intermediate electrolyte filling solution, and the reference electrode tip and a junction at the other end to make contact with the sample.

Salt effect (fx)

The effect on the activity coefficient due to salts in the solution.

SAMA

Scientific Apparatus Makers Association. An association that has issued standards covering platinum, nickel, and copper resistance elements (RTDs).

SCE

Saturated calomel electrode.

SCR

Silicone controlled rectifier.

Scroll

To move all or part of the screen material up to down, left or right, to allow new information to appear.

Secondary device

A part of the flowmeter which receives a signal proportional to the flowrate, from the primary device, and displays, records and/or transmits the signal.

Secondary standard

pH buffer solutions which do not meet the requirements of primary standard solutions but provide coverage of the pH range not covered by primary standards. Used when the pH value of the primary standard is not close to the sample pH value.

Seebeck coefficient

The derivative (rate of change) of thermal EMF with respect to temperature normally expressed as millivolts per degree.

Seebeck effect

When a circuit is formed by a junction of two dissimilar metals and the junctions are held at different temperatures, a current will flow in the circuit caused by the difference in temperature between the two junctions.

Seebeck EMF

The open circuit voltage caused by the difference in temperature between the hot and cold junctions of a circuit made from two dissimilar metals.

Self heating

Internal heating of a transducer as a result of power dissipation.

Sensing element

That part of the transducer which reacts directly in response to the input.

Sensitivity shift

A change in slope of the calibration curve due to a change in sensitivity.

Sensitivity

The minimum change in input signal to which an instrument can respond.

Sequential access

An access mode in which records are retrieved in the same order in which they were written. Each successive access to the file refers to the next record in the file.

Serial transmission

Sending one bit at a time on a single transmission line. Compare with parallel transmission.

Set point

The temperature at which a controller is set to control a system.

Settling time

The time taken for the display to settle within one digit final value when a step is applied to the meter input.

Shear modulus

The ratio of the shear stress and the angular shear distortion.

Shear stress

Where normal stress is perpendicular to the designated plane, shear stress is parallel to the plane.

Shearing strain

A measure of angular distortion also directly measurable, but not as easily as axial strain.

Sheath thermocouple

A thermocouple made out of mineral-insulated thermocouple cable which has an outer metal sheath.

SI – system internationale

The name given to the standard metric system of units.

Signal conditioner

A circuit module which offsets, attenuates, amplifies, linearizes and/or filters the signal for input to the A/D converter. The typical output signal conditioner is +2 V_DC.

Signal conditioning

To process the form or mode of a signal so as to make it intelligible to, or compatible with, a given device, including such manipulation as pulse shaping, pulse clipping, compensating, digitizing, and linearizing.

Signal

An electrical transmittance (either input or output) that conveys information.

Single precision

The degree of numeric accuracy that requires the use of one computer word. In single precision, seven digits are stored, and up to seven digits are printed. Contrast with double precision.

Single-ended input

A signal-input circuit where SIG LO (or sometimes SIG HI) is tied to METER GND. Ground loops are normally not a problem in AC-powered meters, since METER GND is transformer-isolated from AC GND.

Single-plane (static) balancing machine

A single plane balancing machine is a gravitational or centrifugal balancing machine that provides information for accomplishing single plane balancing.

Slope (electrode sensitivity, span)

See Nernst factor.

Smallest bending radius

The smallest radius that a strain guage can withstand in one direction, without special treatment, without suffering visible damage.

Software

Generally, programs loaded into a computer from external mass storage but also extended to include operating systems and documentation.

Solvation

Ions in solution are normally combined with at least one molecule of solvent. This phenomenon is termed solvation.

Source code

A non-executable program written in a high-level language. A compiler or assembler must translate the source code into object code (machine language) that the computer can understand and process.

Span Adjustment

The ability to adjust the gain of a process or strain meter so that a specified display span in engineering units corresponds to a specified signal span. For instance, a display span of 200°F may correspond to the 16mA span of a 4 – 20mA transmitter signal.

Span

The difference between the upper and lower limits of a range expressed in the same units as the range.

Spare

A connector point reserved for options, specials, or other configurations. The point is identified by an (E#) for location on the electrical schematic.

Specific gravity

The ratio of mass of any material to the mass of the same volume of pure water at 4°C.

Specific heat

The ratio of thermal energy required to raise the temperature of a body 1° to the thermal energy required to raise an equal mass of water 1°.

Spectral filter

A filter which allows only a specific band width of the electromagnetic spectrum to pass, i.e., 4 to 8 micron infrared radiation.

Spectrum analysis

Utilizing frequency components of a vibration signal to determine the source and cause of vibration.

Spectrum

The resolving of overall vibration into amplitude components as a function of frequency.

Spot size

The diameter of the circle formed by the cross section of the field of view of an optical instrument at a given distance.

Spurious error

Random or erratic malfunction.

SSR

Solid state relay (see relay, solid state).

Stability

The quality of an instrument or sensor to maintain a consistent output when a constant input is applied.

Stagnation pressure

The sum of the static and dynamic pressure.

Standard electrode potential (E0)

The standard potential E0 of an electrode is the reversible emf between the normal hydrogen electrode and the electrode with all components at unit activity.

Standardization

A process of equalizing electrode potentials in one standardizing solution (buffer) so that potentials developed in unknown solutions can be converted to pH values.

Static calibration

A calibration recording pressure versus output at fixed points at room temperature.

Static error band

The error band applicable at room temperature.

Static pressure

Pressure of a fluid whether in motion or at rest. It can be sensed in a small hole drilled perpendicular to and flush with the flow boundaries so as not to disturb the fluid in any way.

Static unbalance

Static unbalance is that condition of unbalance for which the central principal axis is displayed only parallel to the shaft axis.

Steady flow

A flow rate in the measuring section of a flow line that does not vary significantly with time.

Steady state vibration

That condition of vibration induced by an unchanging continuing periodic force.

Stiffness

The ratio of the force required to create a certain deflection or movement of a part expressed as (Force/deflection) lbs/in or grams/cm.

Stop bit

A signal following a character or block that prepares the receiving device to receive the next character or block.

Strain guage

A measuring element for converting force, pressure, tension, etc., into an electrical signal.

Strain

The ratio of the change in length to the initial unstressed reference length.

String

A sequence of characters.

Strouhal number

A nondimensional parameter important in vortex meter design defined as: s = Fh/V where f = frequency, V = velocity, and h = a reference length.

Super cooling

The cooling of a liquid below its freezing temperature without the formation of the solid phase.

Super heating

1. The heating of a liquid above its boiling temperature without the formation of the gaseous phase.
2. The heating of the gaseous phase considerably above the boiling-point temperature to improve the thermodynamic efficiency of a system.

Surge current

A current of short duration that occurs when power is first applied to capacitive loads or temperature dependent resistive loads such as tungsten or molybdenum heaters-usually lasting no more than several cycles.

Suspension effect

The source of error due to varied reference liquid junction potential depending upon whether the electrodes are immersed in the supernatant fluid or deeper in the sediment. Normally encountered with solutions containing resins or charged colloids.

Syntax

The rules governing the structure of a language.

Tape

A recording media for data or computer programs. Tape can be in permanent form, such as perforated paper tape, or erasable, such as magnetic tape. Generally, tape is used as a mass storage medium, in magnetic form, and has a much higher storage capacity than disk storage, but it takes much longer to write or recover data from tape than from a disk.

Telecommunication

Synonym for data communication. The transmission of information from one point to another.

TEMPCO

Abbreviation for “temperature coefficient”: the error introduced by a change in temperature. Normally expressed in %/°C or ppm/°C.

Temperature error

The maximum change in output, at any measurand value within the specified range, when the transducer temperature is changed from room temperature to specified temperature extremes.

Temperature range, compensated

The range of ambient temperatures within which all tolerances specified for Thermal Zero Shift and Thermal Sensitivity Shift are applicable (temperature error).

Temperature range, operable

The range of ambient temperatures, given by their extremes, within which the transducer may be operated. Exceeding compensated range may require recalibration.

Terminal

An input/output device used to enter data into a computer and record the output.

Thermal coefficient of resistance

The change in resistance of a semiconductor per unit change in temperature over a specific range of temperature.

Thermal conductivity

The property of a material to conduct heat in the form of thermal energy.

Thermal emf

See Seebeck emf.

Thermal expansion

An increase in size due to an increase in temperature expressed in units of an increase in length or increase in size per degree, i.e. inches/inch/degree C.

Thermal gradient

The distribution of a differential temperature through a body or across a surface.

Thermal sensitivity shift

The sensitivity shift due to changes of the ambient temperature from room temperature to the specified limits of the compensated temperature range.

Thermal zero shift

An error due to changes in ambient temperature in which the zero pressure output shifts. Thus, the entire calibration curve moves in a parallel displacement.

Thermistor

A temperature-sensing element composed of sintered semiconductor material which exhibits a large change in resistance proportional to a small change in temperature. Thermistors usually have negative temperature coefficients.

Thermocouple type material

(ANSI Symbol)
J  Iron/Constantan
K  CHROMEGA®/ALOMEGA®
T  Copper/Constantan
E  CHROMEGA®/Constantan
R  Platinum/Platinum 13% Rhodium
S  Platinum/Platinum 10% Rhodium
B  Platinum 6% Rhodium/Platinum30% Rhodium
G*  Tungsten/Tungsten 26% Rhenium
C*  Tungsten 5% Rhenium/Tungsten 26% Rhenium
D*  Tungsten 3% Rhenium/Tungsten 150 Rhenium
*Not ANSI symbols.

Thermocouple

The junction of two dissimilar metals which has a voltage output proportional to the difference in temperature between the hot junction and the lead wires (cold junction) (refer to Seebeck emf).

Thermopile

An arrangement of thermocouples in series such that alternate junctions are at the measuring temperature and the reference temperature. This arrangement amplifies the thermoelectric voltage. Thermopiles are usually used as infrared detectors in radiation pyrometry.

Thermowell

A closed-end tube designed to protect temperature sensors from harsh environments, high pressure, and flows. They can be installed into a system by pipe thread or welded flange and are usually made of corrosion-resistant metal or ceramic material depending upon the application.

Thomson effect

When current flows through a conductor within a thermal gradient, a reversible absorption or evolution of heat will occur in the conductor at the gradient boundaries.
Transducer Vibration: Generally, any device which converts movement, either shock or steady state vibration, into an electrical signal proportional to the movement; a sensor.

Transducer

A device (or medium) that converts energy from one form to another. The term is generally applied to devices that take physical phenomenon (pressure, temperature, humidity, flow, etc.) and convert it to an electrical signal.

Transient vibration

A temporary vibration or movement of a mechanical system.

Transitional flow

Flow between laminar and turbulent flow, usually between a pipe Reynolds number of 2000 and 4000.

Transmitter (two-wire)

1. A device which is used to transmit data from a sensor via a two-wire current loop. The loop has an external power supply and the transmitter acts as a variable resistor with respect to its input signal.
2. A device which translates the low level output of a sensor or transducer to a higher level signal suitable for transmission to a site where it can be further processed.

Triac

A solid state switching device used to switch alternating current wave forms.

Triboelectric noise

The generation of electrical charges caused by layers of cable insulation. This is especially troublesome in high impedance accelerometers.

Triple point (water)

The thermodynamic state where all three phases, solid, liquid, and gas may all be present in equilibrium. The triple point of water is .01°C.

Triple point

The temperature and pressure at which solid, liquid, and gas phases of a given substance are all present simultaneously in varying amounts.

True RMS

The true root-mean-square value of an AC or AC-plus-DC signal, often used to determine power of a signal. For a perfect sine wave, the RMS value is 1.11072 times the rectified average value, which is utilized for low-cost metering. For significantly non-sinusoidal signals, a true RMS converter is required.

TTL unit load

A load with TTL voltage levels, which will draw 40 µA for a logic 1 and –1.6mA for a logic 0.

TTL-compatible

For digital input circuits, a logic 1 is obtained for inputs of 2.0 to 5.5V which can source 40µA, and a logic 0 is obtained for inputs of 0 to 0.8V which can sink 1.6mA. For digital output signals, a logic 1 is represented by 2.4 to 5.5V with a current source capability of at least 400µA; and a logic 0 is represented by 0 to 0.6V with a current sink capability of at least 16mA.

TTL

Transistor-to-transistor logic. A form of solid state logic which uses only transistors to form the logic gates.

Turbulent flow

When forces due to inertia are more significant than forces due to viscosity. This typically occurs with a Reynolds number in excess of 4000.

Typical

Error is within plus or minus one standard deviation (±1%) of the nominal specified value, as computed from the total population.

UL

Underwriters Laboratories, Inc. An independent laboratory that establishes standards for commercial and industrial products.

Ultraviolet

That portion of the electromagnetic spectrum below blue light (380 nanometers).

Unbalance

That condition which exists in a rotor when vibratory force or motion is imparted to its bearings as a result of centrifugal forces.

Unbalance tolerance

The unbalance tolerance with respect to a radial plane (measuring plane or correction plane) is that amount of unbalance which is specified as the maximum below which the state of unbalance is considered acceptable.

Undershoot

The difference in temperature between the temperature a process goes to, below the set point, after the cooling cycle is turned off and the set point temperature.

Ungrounded junction

A form of construction of a thermocouple probe where the hot or measuring junction is fully enclosed by and insulated from the sheath material.

Union

A form of pipe fitting where two extension pipes are joined at a separable coupling.

Vacuum

Any pressure less than atmospheric pressure.

Velocity

The time rate of change of displacement; dx/dt.

Vibration error band

The error recorded in output of a transducer when subjected to a given set of amplitudes and frequencies.

Vibration error

The maximum change in output of a transducer when a specific amplitude and range of frequencies are applied to a specific axis at room temperature.

Viscosity

The inherent resistance of a substance to flow.

Volt

The (electrical) potential difference between two points in a circuit. The fundamental unit is derived as work per unit charge-(V = W/Q). One volt is the potential difference required to move one coulomb of charge between two points in a circuit while using one joule of energy.

Voltage

An electrical potential which can be measured in volts.

Voltmeter

An instrument used to measure voltage.

Volume flow rate

Calculated using the area of the full closed conduit and the average fluid velocity in the form, Q = V x A, to arrive at the total volume quantity of flow. Q = volumetric flowrate, V = average fluid velocity, and A = cross sectional area of the pipe.

Watt density

The watts emanating from each square inch of heated surface area of a heater. Expressed in units of watts per square inch.

Wheatstone bridge

A network of four resistances, an emf source, and a galvanometer connected such that when the four resistances are matched, the galvanometer will show a zero deflection or “null” reading.

Window

In computer graphics, a defined area in a system not bounded by any limits; unlimited “space” in graphics.

Word

Number of bits treated as a single unit by the CPU. In an 8-bit machine, the word length is 8 bits; in a sixteen bit machine, it is 16 bits.

Working standard

A standard of unit measurement calibrated from either a primary or secondary standard which is used to calibrate other devices or make comparison measurements.

Write

To record data in a storage device or on a data medium.

Young’s Modulus

Young’s Modulus (the Modulus of Elasticity) is equivalent to the ratio of normal stress to strain.

Zero adjustment

The ability to adjust the display of a process or strain meter so that zero on the display corresponds to a non-zero signal, such as 4 mA, 10 mA, or 1 V dc. The adjustment range is normally expressed in counts.

Zero offset

1. The difference expressed in degrees between true zero and an indication given by a measuring instrument.
2. See Zero Suppression

Zero point

The electrical zero point where zero millivolts would be displayed. Used in conjunction with the slope control to provide a narrower range calibration.

Zero power resistance

The resistance of a thermistor or RTD element with no power being dissipated.

Zero suppression

The span of an indicator or chart recorder may be offset from zero (zero suppressed) such that neither limit of the span will be zero. For example, a temperature recorder which records a 100° span from 400° to 500° is said to have 400° zero suppression.

Zero voltage switching

The making or breaking of circuit timed such that the transition occurs when the voltage wave form crosses zero voltage; typically only found in solid state switching devices.

Zooming

In computer graphics, causing an object to appear smaller or larger by moving the window and specifying various window sizes.