HONEYWELL 51454408-175 CC-PDOD51系统模块卡件
电流不平衡分别为6、12、18、24和30%。基于此假设，GE Multiline曲线说明了为UNBALANCE BIAS k FACTOR（不平衡偏置k系数）设定值输入的不同k值的电机降额。注意，当k=8时创建的曲线几乎与NEMA降额曲线相同。图4–12：由于电压不平衡导致的中等电机减额因数如果输入k值为0，则不平衡偏置将失效，过载曲线将根据测量的每单位电机电流超时。k可以保守计算为：（EQ 4.4）e）电机冷却当电机电流小于过载拾取设置点时，所用热容量值呈指数下降。这种减少模拟了电机冷却。应输入停止和运行情况下的电机冷却时间常数。由于冷却是指数型的，时间常数是从100%热容量到0%总时间的五分之一。停止的电机通常比运行的电机冷却得慢得多。电机冷却计算为：（EQ 4.5）（EQ 4.6）其中：TCused=热f）热/冷曲线比率电机制造商可提供热/冷电机的热极限信息。如果编程了热/冷曲线比率设定值，469热模型将适应这些条件。该设定值规定了继电器在电流水平低于过载拾取水平时所使用的热容量水平。当电机以低于过载拾取水平的水平运行时，所用热容量寄存器将上升或下降至基于平均相电流和热/冷曲线比率设定值的值。所用热容量将以每分钟5%的固定速率上升，或根据运行冷却时间常数下降。（EQ 4.7）式中：TCused_end=如果Iper_unit保持稳定状态，则使用的热容量Ieq=等效电机加热电流热/冷=热/冷曲线比率设定值热/冷的曲线比率可根据热极限曲线（如果提供）或热/冷安全失速时间确定。只需将热安全失速时间除以冷安全失速时间。如果不提供热时间和冷时间，不能有任何差异，热/冷曲线比率应输入为“1.00”。808705A1.CDR 0 25 50 75 100 0 30 60 90 150 180时间（以分钟为单位）使用的热容量冷却时间常数=15分钟TCused_start=85%热/冷比率=80%Ieq/过载拾取=100%0 25 50 100 0 30 90 120 150 180时间，以分钟为分钟使用的热能力冷却时间常数=15分钟TCused_start=85%热/冷比=80%Ieq/过载拾取=80%0 25 50 75 100 0 30 60 90 120 150 180分钟热容量使用冷却时间常数=30分钟TCused_start=85%热/冷比率=80%电机在运行额定负载后停止TCused_end=0%0 25 50 100 30 60 90 150 180分钟冷容量使用冷却温度常数=30 min TCused_start=100%热/冷比例=80%电机停止过载跳闸后TCused_end=0%电机跳闸100%负载电机停止80%负载TCused_end Ieq 1热-冷 = ××100%GE Multilin 469电机管理继电器4-41 4设定值4.6 S5热模型4 g）RTD偏置469热复制品作为一个完整的独立模型运行。然而，热过载曲线仅基于测量电流，假设环境温度为40°C，电机冷却正常。如果环境温度异常高，或电机冷却受阻，电机温度将升高。如果电机定子具有嵌入式RTD，则应使用469 RTD偏置特性来校正热模型。RTD偏置特性为两部分曲线，由3个点构成。如果最大定子RTD温度低于RTD偏置最小设定值（通常为40°C），则不会发生偏置。
current unbalances of 6, 12, 18, 24, and 30% respectively. Based on this assumption, the GE Multilin curve illustrates the motor derating for different values of k entered for the UNBALANCE BIAS K FACTOR setpoint. Note that the curve created when k = 8 is almost identical to the NEMA derating curve. Figure 4–12: MEDIUM MOTOR DERATING FACTOR DUE TO UNBALANCED VOLTAGE If a k value of 0 is entered, the unbalance biasing is defeated and the overload curve will time out against the measured per unit motor current. k may be calculated conservatively as: (EQ 4.4) e) MOTOR COOLING The thermal capacity used value decreases exponentially when the motor current is less than the OVERLOAD PICKUP setpoint. This reduction simulates motor cooling. The motor cooling time constants should be entered for both stopped and running cases. Since cooling is exponential, the time constants are one-fifth of the total time from 100% thermal capacity used to 0%. A stopped motor normally cools significantly slower than a running motor. Motor cooling is calculated as: (EQ 4.5) (EQ 4.6) where: TCused = thermal f) HOT/COLD CURVE RATIO The motor manufacturer may provide thermal limit information for a hot/cold motor. The 469 thermal model adapts for these conditions if the HOT/COLD CURVE RATIO setpoint is programmed. This setpoint value dictates the level of thermal capacity used the relay will settle at for current levels below the OVERLOAD PICKUP LEVEL. When the motor is running at a level that is below the OVERLOAD PICKUP LEVEL, the THERMAL CAPACITY USED register will rise or fall to a value based on the average phase current and the HOT/COLD CURVE RATIO setpoint. The THERMAL CAPACITY USED will either rise at a fixed rate of 5% per minute or fall as dictated by the running cool time constant. (EQ 4.7) where: TCused_end = THERMAL CAPACITY USED if Iper_unit remains steady state Ieq = equivalent motor heating current hot / cold = HOT/COLD CURVE RATIO setpoint The HOT/COLD CURVE RATIO may be determined from the thermal limit curves if provided or the hot and cold safe stall times. Simply divide the hot safe stall time by the cold safe stall time. If hot and cold times are not provided, there can be no differentiation and the HOT/COLD CURVE RATIO should be entered as "1.00". 808705A1.CDR 0 25 50 75 100 0 30 60 90 120 150 180 Time in Minutes Thermal Capacity Used Cool Time Constant= 15 min TCused_start= 85% Hot/Cold Ratio= 80% Ieq/Overload Pickup= 100% 0 25 50 75 100 0 30 60 90 120 150 180 Time in Minutes Thermal Capacity Used Cool Time Constant= 15 min TCused_start= 85% Hot/Cold Ratio= 80% Ieq/Overload Pickup= 80% 0 25 50 75 100 0 30 60 90 120 150 180 Time in Minutes Thermal Capacity Used Cool Time Constant= 30 min TCused_start= 85% Hot/Cold Ratio= 80% Motor Stopped after running Rated Load TCused_end= 0% 0 25 50 75 100 0 30 60 90 120 150 180 Time in Minutes Thermal Capacity Used Cool Time Constant= 30 min TCused_start= 100% Hot/Cold Ratio= 80% Motor Stopped after Overload Trip TCused_end= 0% MOTOR TRIPPED 100% LOAD MOTOR STOPPED 80% LOAD TCused_end Ieq 1 hot cold – ---------- = × × 100% GE Multilin 469 Motor Management Relay 4-41 4 SETPOINTS 4.6 S5 THERMAL MODEL 4 g) RTD BIAS The 469 thermal replica operates as a complete and independent model. The thermal overload curves however, are based solely on measured current, assuming a normal 40°C ambient and normal motor cooling. If the ambient temperature is unusually high, or if motor cooling is blocked, the motor temperature will increase. If the motor stator has embedded RTDs, the 469 RTD bias feature should be used to correct the thermal model. The RTD bias feature is a two-part curve, constructed using 3 points. If the maximum stator RTD temperature is below the RTD BIAS MINIMUM setpoint (typically 40°C), no biasing occurs.
