Setting the thermal restart levelThe restart disable level can be calculated as follows:θi startup time of the motoroperate time when no prior load= − ×100 10% 00% + marginGUID-5B3B714D-8C58-4C5D-910D-A23852BC8B15 V1 EN (Equation 14)For example, the motor startup time is 11 seconds, start-up current 6 x rated andTime constant start is set for 800 seconds. Using the trip curve with no prior load,the operation time at 6 x rated current is 25 seconds, one motor startup uses 11/25≈ 45 percent of the thermal capacity of the motor. Therefore, the restart disablelevel must be set to below 100 percent - 45 percent = 55 percent, for example to 50percent (100 percent - (45 percent + margin), where margin is 5 percent).Setting the thermal alarm levelTripping due to high overload is avoided by reducing the load of the motor on aprior alarm.The value of Alarm thermal value is set to a level which allows the use of the fullthermal capacity of the motor without causing a trip due to a long overload time.Generally, the prior alarm level is set to a value of 80 to 90 percent of the trip level.4.1.9.6 SignalsTable 258:MPTTR Input signalsName Type Default DescriptionI_A SIGNAL 0 Phase A currentI_B SIGNAL 0 Phase B currentI_C SIGNAL 0 Phase C currentI2 SIGNAL 0 Negative sequence currentBLOCK BOOLEAN 0=False Block signal for activating the blocking modeSTART_EMERG BOOLEAN 0=False Signal for indicating the need for emergency startTEMP_AMB FLOAT32 0 The ambient temperature used in the calculationTable 259:MPTTR Output signalsName Type DescriptionOPERATE BOOLEAN OperateALARM BOOLEAN Thermal AlarmBLK_RESTART BOOLEAN Thermal overload indicator, to inhibit restartSection 4 1YHT530004D05 DProtection functions260 615 seriesTechnical Manual
