HONEYWELL CC-TAID11工控模块卡件
对于高于所述电压的值，469将安全失速保护曲线外推至110%电压。通过取100%电压下的锁定转子电流并乘以1.10来计算该电流水平。对于超过110%电流水平的跳闸时间，将使用110%的跳闸时间。（见下图）。图4-10：电压相关过载保护曲线安全失速曲线实际上是不同电压下的一系列安全失速点。对于给定电压，只有一个失速电流值，因此只有一个安全失速时间。1 123 456 78 2 3 4 5 6 7 8 9 10 20 30 40 50 60 80 90 100高惯性负载过载曲线8800 HP，13.2 kV，反应堆冷却剂泵跳闸时间（秒）满载安培数200 300 400 500 600 700 800 900 1000加速相交于80%V自定义曲线加速相交于100%V 80%V安全失速时间，80%V失速电流安全失速时间，100%V失速电流安全失速点外推至110%V 806824A4.CDR GE Multilin注释4-38 469电机管理继电器GE Multilin 4.6 S5热模型4设定值4以下两个图分别说明了80%和100%线路电压的合成过载保护曲线。对于介于两者之间的电压，469将基于电机启动期间测得的线电压线性且恒定地移动加速度曲线。图4–11：80%和100%电压下的电压相关过载保护d）不平衡偏置不平衡相电流也会导致额外的转子发热，机电继电器和一些电子保护继电器也不考虑。当电机运行时，转子以接近同步的速度沿正序电流的方向旋转。负序电流的相位旋转与正序电流相反（因此，与转子旋转相反），产生转子电压，产生大量转子电流。该感应电流的频率约为线路频率的2倍：50Hz系统为100Hz，60Hz系统为120Hz。在该频率下，转子棒中的趋肤效应导致转子电阻显著增加，因此转子加热显著增加。电机制造商提供的热极限曲线中未考虑这种额外的加热，因为这些曲线仅假设电源和电机设计完全平衡的正序电流。469测量负序电流与正序电流的比率。热模型可以被偏置以反映在电机运行时由负序电流引起的额外加热。这种偏置是通过创建等效的电机加热电流而不是简单地使用平均电流（Iper_unit）来实现的。使用下面所示的公式计算该等效电流。1 123 456 78 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70 90 100高惯性负载过载曲线8800 HP，13.2 kV，反应堆冷却剂泵跳闸时间（秒）满载安培数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高惰性负载过载曲线8600 HP，13.2kV，反应堆冷却剂泵跳闸时间（秒）多个满载电流200 300 400 500 600 700 900 1000 GE Multilin 806826A4.CDR GE Multilin 469电机管理继电器4-39 4设定值4.6 S5热模型4（EQ 4.3）其中：Ieq=等效电机加热电流Iper_unit=基于FLA的每单位电流I2=负序电流I1=正序电流k=常数以下显示了NEMA（美国国家电气制造商协会）推荐的根据电压不平衡的推荐电机降额。假设典型的感应电机具有6 x FLA的浪涌和0.167的负序阻抗，则1、2、3、4和5%的电压不平衡相等
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
