HONEYWELL CC-TAID11工控模塊卡件
對于高于所述電壓的值，469將安全失速保護曲線外推至110%電壓。通過取100%電壓下的鎖定轉子電流并乘以1.10來計算該電流水平。對于超過110%電流水平的跳閘時間，將使用110%的跳閘時間。（見下圖）。圖4-10：電壓相關過載保護曲線安全失速曲線實際上是不同電壓下的一系列安全失速點。對于給定電壓，只有一個失速電流值，因此只有一個安全失速時間。1 123 456 78 2 3 4 5 6 7 8 9 10 20 30 40 50 60 80 90 100高慣性負載過載曲線8800 HP，13.2 kV，反應堆冷卻劑泵跳閘時間（秒）滿載安培數(shù)200 300 400 500 600 700 800 900 1000加速相交于80%V自定義曲線加速相交于100%V 80%V安全失速時間，80%V失速電流安全失速時間，100%V失速電流安全失速點外推至110%V 806824A4.CDR GE Multilin注釋4-38 469電機管理繼電器GE Multilin 4.6 S5熱模型4設定值4以下兩個圖分別說明了80%和100%線路電壓的合成過載保護曲線。對于介于兩者之間的電壓，469將基于電機啟動期間測得的線電壓線性且恒定地移動加速度曲線。圖4–11：80%和100%電壓下的電壓相關過載保護d）不平衡偏置不平衡相電流也會導致額外的轉子發(fā)熱，機電繼電器和一些電子保護繼電器也不考慮。當電機運行時，轉子以接近同步的速度沿正序電流的方向旋轉。負序電流的相位旋轉與正序電流相反（因此，與轉子旋轉相反），產生轉子電壓，產生大量轉子電流。該感應電流的頻率約為線路頻率的2倍：50Hz系統(tǒng)為100Hz，60Hz系統(tǒng)為120Hz。在該頻率下，轉子棒中的趨膚效應導致轉子電阻顯著增加，因此轉子加熱顯著增加。電機制造商提供的熱極限曲線中未考慮這種額外的加熱，因為這些曲線僅假設電源和電機設計完全平衡的正序電流。469測量負序電流與正序電流的比率。熱模型可以被偏置以反映在電機運行時由負序電流引起的額外加熱。這種偏置是通過創(chuàng)建等效的電機加熱電流而不是簡單地使用平均電流（Iper_unit）來實現(xiàn)的。使用下面所示的公式計算該等效電流。1 123 456 78 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70 90 100高慣性負載過載曲線8800 HP，13.2 kV，反應堆冷卻劑泵跳閘時間（秒）滿載安培數(shù)200 300 400 500 600 700 800 900 1000 GE Multilin 806825A4.CDR 1 123 456 8 2 3 4 6 7 9 10 20 40 50 60 80 90 100高惰性負載過載曲線8600 HP，13.2kV，反應堆冷卻劑泵跳閘時間（秒）多個滿載電流200 300 400 500 600 700 900 1000 GE Multilin 806826A4.CDR GE Multilin 469電機管理繼電器4-39 4設定值4.6 S5熱模型4（EQ 4.3）其中：Ieq=等效電機加熱電流Iper_unit=基于FLA的每單位電流I2=負序電流I1=正序電流k=常數(shù)以下顯示了NEMA（美國國家電氣制造商協(xié)會）推薦的根據(jù)電壓不平衡的推薦電機降額。假設典型的感應電機具有6 x FLA的浪涌和0.167的負序阻抗，則1、2、3、4和5%的電壓不平衡相等
For values above the voltage in question, the 469 extrapolates the safe stall protection curve to 110% voltage. This current level is calculated by taking the locked rotor current at 100% voltage and multiplying by 1.10. For trip times above the 110% current level, the trip time of 110% will be used. (see figure below). Figure 4–10: VOLTAGE DEPENDENT OVERLOAD PROTECTION CURVES The safe stall curve is in reality a series of safe stall points for different voltages. For a given voltage, there can only be one value of stall current and therefore, only one safe stall time. 1 123 456 78 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70 80 90 100 HIGH INERTIA LOAD OVERLOAD CURVES 8800 HP, 13.2 kV, REACTOR COOLANT PUMP TIME TO TRIP (SECONDS) MULTIPLES OF FULL LOAD AMPS 200 300 400 500 600 700 800 900 1000 Acceleration Intersect at 80%V Custom Curve Acceleration Intersect at 100%V Safe Stall Time at 80%V, 80%V Stall Current Safe Stall Time at 100%V, 100%V Stall Current Safe Stall Points Extrapolated to 110%V 806824A4.CDR GE Multilin NOTE 4-38 469 Motor Management Relay GE Multilin 4.6 S5 THERMAL MODEL 4 SETPOINTS 4 The following two figures illustrate the resultant overload protection curves for 80% and 100% line voltage, respectively. For voltages in between, the 469 will shift the acceleration curve linearly and constantly based on measured line voltage during a motor start. Figure 4–11: VOLTAGE DEPENDENT OVERLOAD PROTECTION AT 80% AND 100% VOLTAGE d) UNBALANCE BIAS Unbalanced phase currents also cause additional rotor heating not accounted for by electromechanical relays and also not accounted for in some electronic protective relays. When the motor is running, the rotor rotates in the direction of the positive-sequence current at near synchronous speed. Negative-sequence current, with a phase rotation opposite to positivesequence current (and hence, opposite to the rotor rotation), generates a rotor voltage that produces a substantial rotor current. This induced current has a frequency approximately 2 times the line frequency: 100 Hz for a 50 Hz system or 120 Hz for a 60 Hz system. The skin effect in the rotor bars at this frequency causes a significant increase in rotor resistance and therefore a significant increase in rotor heating. This extra heating is not accounted for in the thermal limit curves supplied by the motor manufacturer, as these curves assume only positive-sequence currents from a perfectly balanced supply and motor design. The 469 measures the ratio of negative to positive-sequence current. The thermal model may be biased to reflect the additional heating that is caused by negative sequence current when the motor is running. This biasing is accomplished by creating an equivalent motor heating current rather than simply using average current (Iper_unit). This equivalent current is calculated using the equation shown below. 1 123 456 78 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70 80 90 100 HIGH INERTIA LOAD OVERLOAD CURVES 8800 HP, 13.2 kV, REACTOR COOLANT PUMP TIME TO TRIP (SECONDS) MULTIPLES OF FULL LOAD AMPS 200 300 400 500 600 700 800 900 1000 GE Multilin 806825A4.CDR 1 123 456 78 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70 80 90 100 HIGH INERTIA LOAD OVERLOAD CURVES 8800 HP, 13.2 kV, REACTOR COOLANT PUMP TIME TO TRIP (SECONDS) MULTIPLES OF FULL LOAD AMPS 200 300 400 500 600 700 800 900 1000 GE Multilin 806826A4.CDR GE Multilin 469 Motor Management Relay 4-39 4 SETPOINTS 4.6 S5 THERMAL MODEL 4 (EQ 4.3) where: Ieq = equivalent motor heating current Iper_unit = per unit current based on FLA I2= negative sequence current I1= positive sequence current k = constant The figure below shows recommended motor derating as a function of voltage unbalance recommended by NEMA (the National Electrical Manufacturers Association). Assuming a typical induction motor with an inrush of 6 x FLA and a negative sequence impedance of 0.167, voltage unbalances of 1, 2, 3, 4, and 5% equal
