ICS TRIPLEX T3470A模擬量輸入模塊
必須注意的缺點是：1。由于導線和連接電阻，溫度讀數會有誤差。不建議在10? 銅RTD。2.如果通向469或任何跳線的RTD回路斷開，則斷開點的所有RTD讀數將為開路。3.如果補償導線或任何跳線斷開，斷開點的所有RTD將在沒有任何導線補償的情況下工作。c） 雙線RTD引線補償下圖顯示了如何將引線補償添加到雙線RTD的示例。圖2–20：2線RTD引線補償增加補償引線L2，以補償熱（L1）和回流（L3），假設它們都具有相同的長度和規格。為了補償導線RL1和RL2，可以在補償導線上增加一個等于RL1或RL2電阻的電阻，盡管在許多情況下這是不必要的。d） RTD接地RTD的一根引線在469或電機處接地。不應在兩個地方進行接地，因為這可能會導致循環電流。只有RTD回路引線可以接地。在469處接地時，只有一根回流導線需要接地，因為它們內部硬接線在一起。通過這種方式接地，RTD讀數不會出現誤差。如果RTD回路引線連接在一起并在電機處接地，則只能將一條RTD回路引線引回469。有關接線示例，請參見下圖。在469上運行多條RTD回路導線會導致嚴重錯誤，因為已經為回路電流創建了兩條或多條并聯路徑。使用此接線方案會導致讀數誤差，與前面所述的減少RTD引線數應用中的讀數誤差相當。圖2–21：RTD交替接地808719A1.CDR 469電機控制接線盒電機熱補償RTD回路A1 A2 A3 L1 L3 Rcomp RTD1 RL1 RL2+–GE Multilin 469電機管理繼電器2-17 2安裝2.2電氣2 2.2.9輸出繼電器繼電器觸點在469通電時接觸不安全！如果低壓可接近應用需要輸出繼電器觸點，則客戶有責任確保適當的絕緣水平。有六（6）個C型輸出繼電器（詳見第1-4頁第1.2節：規范）。六個繼電器中的五個始終是非故障安全的；R6服務始終是故障安全的。作為故障保護，R6繼電器通常通電，并在需要操作時斷電。當469控制電源丟失并將處于其操作狀態時，它也會斷電。所有其他非故障保護繼電器通常在需要操作時斷電和通電。當469控制電源丟失時，這些繼電器斷電并處于非操作狀態。抽出式外殼中的短路桿確保在抽出469時不會發生跳閘或報警。然而，R6服務輸出將指示469已被取出。每個輸出繼電器在前面板上有一個LED指示燈，當相關繼電器處于工作狀態時，該指示燈點亮。?R1跳閘：跳閘繼電器應接線，以便在條件允許時使電機離線。對于斷路器應用，NO R1跳閘觸點應與斷路器跳閘線圈串聯。用于接觸器
isadvantages must be noted: 1. There will be an error in temperature readings due to lead and connection resistances. This technique is NOT recommended for 10 ? Copper RTDs. 2. If the RTD Return lead to the 469 or any of the jumpers break, all RTDs from the point of the break will read open. 3. If the Compensation lead or any of the jumpers break, all RTDs from the point of the break will function without any lead compensation. c) TWO-WIRE RTD LEAD COMPENSATION An example of how to add lead compensation to a two wire RTD may is shown in the figure below. Figure 2–20: 2-WIRE RTD LEAD COMPENSATION The compensation lead L2 is added to compensate for Hot (L1) and Return (L3), assuming they are all of equal length and gauge. To compensate for leads RL1 and RL2, a resistor equal to the resistance of RL1 or RL2 could be added to the compensation lead, though in many cases this is unnecessary. d) RTD GROUNDING Grounding of one lead of the RTDs is done at either the 469 or at the motor. Grounding should not be done in both places as it could cause a circulating current. Only RTD Return leads may be grounded. When grounding at the 469, only one Return lead need be grounded as they are hard-wired together internally. No error is introduced into the RTD reading by grounding in this manner. If the RTD Return leads are tied together and grounded at the motor, only one RTD Return lead can be run back to the 469. See the figure below for a wiring example. Running more than one RTD Return lead to the 469 causes significant errors as two or more parallel paths for the return current have been created. Use of this wiring scheme causes errors in readings equivalent to that in the Reduced RTD Lead Number application described earlier. Figure 2–21: RTD ALTERNATE GROUNDING 808719A1.CDR 469 Motor Control Terminal Box Motor Hot Compensation RTD Return A1 A2 A3 L1 L2 L3 Rcomp RTD1 RL1 RL2 + – GE Multilin 469 Motor Management Relay 2-17 2 INSTALLATION 2.2 ELECTRICAL 2 2.2.9 OUTPUT RELAYS Relay contacts must be considered unsafe to touch when the 469 is energized! If the output relay contacts are required for low voltage accessible applications, it is the customer’s responsibility to ensure proper insulation levels. There are six (6) Form-C output relays (see Section 1.2: Specifications on page 1–4 for details). Five of the six relays are always non-failsafe; R6 Service is always failsafe. As failsafe, the R6 relay is normally energized and de-energizes when called upon to operate. It also de-energizes when 469 control power is lost and will be in its operated state. All other relays, being non-failsafe, will normally be de-energized and energize when called upon to operate. When the 469 control power is lost, these relays are de-energized and in their non-operated state. Shorting bars in the drawout case ensure that no trip or alarm occurs when the 469 is drawn out. However, the R6 Service output will indicate that the 469 has been drawn out. Each output relay has an LED indicator on the front panel that turns on when the associated relay is in the operated state. ? R1 TRIP: The trip relay should be wired to take the motor off line when conditions warrant. For a breaker application, the NO R1 Trip contact should be wired in series with the Breaker trip coil. For contactor
