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Home » Motor control » Motor controlled by soft starter but trip frequent
Motor controlled by soft starter but trip frequent
To figure out what's the factor cause motor tripped, following steps may help you:
1) Your Breaker or Motor Circuit Protector Rating. What is AT rating of that breaker. That must be covering your full load capacity of Motor.
2) The motor is tripping due to overload. I think overload relay setting should be checked. As a thumb rule, this relay shall be set between 15 to 20% of motor full load current. Check manufacturer's recommendations for required settings.
3) if the trip appears at the motor start phase the soft start can be failed, because it should reduce the current to the limit value.
4) if the trip appears when the soft starter is bypassed then the motor is mechanically overloaded.
5) Check the soft starter settings. There should be ramp up time of 10 sec and initial voltage to be 40%.
If it is a new installation check the earthing of soft starter. Please follow the instructions given for the soft starter faithfully. Since Electronics is involved the thrusters and PCB will misbehave if the earthing is not proper.
There are two reasons for tripping of motor:
1. If the load characteristics do not match with the motor characteristics, i.e. if load takes more time to pick up than motor is designed, i.e. if startup load amps take larger time than motor is designed to deliver.
2. As mentioned earlier, thermal overload realy settings. Many times manufactures do not set these relays.
You should check overload relay settings on relay and manufacturer's O&M manuals and/or manufacturer for actual settings to overcome this problem.
If it trips during staring in morning hours when ambient temperature is low. Just increase your starting time setting on relay by 2-3 seconds i.e. if it is set 10 sec increase to 12-13 sec and so it will prevent motor tripping due to high viscosity.
However make sure any incremental changes in relay settings shall be within the protective zone of motor insulation characteristics.
- Check the system voltage, any decrease in voltage will have proportionate effect on motor torque, i.e. if voltage is 5% less than nominal, the current will increase by 5% to compensate for required torque, which will increase motor load and hence overload action.
- You should check starting/running current (thru meter) vis-a-vis relay thermal o/l setting requirements.
- Phase imbalance could also have overload problem for motor to trip. Insure phases are balanced within required tolerance.
- Viscosity, as mentioned, is main source of o/l tripping. The designer should have considered this requirement during sizing of motor/drive.
1) Your Breaker or Motor Circuit Protector Rating. What is AT rating of that breaker. That must be covering your full load capacity of Motor.
2) The motor is tripping due to overload. I think overload relay setting should be checked. As a thumb rule, this relay shall be set between 15 to 20% of motor full load current. Check manufacturer's recommendations for required settings.
3) if the trip appears at the motor start phase the soft start can be failed, because it should reduce the current to the limit value.
4) if the trip appears when the soft starter is bypassed then the motor is mechanically overloaded.
5) Check the soft starter settings. There should be ramp up time of 10 sec and initial voltage to be 40%.
If it is a new installation check the earthing of soft starter. Please follow the instructions given for the soft starter faithfully. Since Electronics is involved the thrusters and PCB will misbehave if the earthing is not proper.
There are two reasons for tripping of motor:
1. If the load characteristics do not match with the motor characteristics, i.e. if load takes more time to pick up than motor is designed, i.e. if startup load amps take larger time than motor is designed to deliver.
2. As mentioned earlier, thermal overload realy settings. Many times manufactures do not set these relays.
You should check overload relay settings on relay and manufacturer's O&M manuals and/or manufacturer for actual settings to overcome this problem.
If it trips during staring in morning hours when ambient temperature is low. Just increase your starting time setting on relay by 2-3 seconds i.e. if it is set 10 sec increase to 12-13 sec and so it will prevent motor tripping due to high viscosity.
However make sure any incremental changes in relay settings shall be within the protective zone of motor insulation characteristics.
- Check the system voltage, any decrease in voltage will have proportionate effect on motor torque, i.e. if voltage is 5% less than nominal, the current will increase by 5% to compensate for required torque, which will increase motor load and hence overload action.
- You should check starting/running current (thru meter) vis-a-vis relay thermal o/l setting requirements.
- Phase imbalance could also have overload problem for motor to trip. Insure phases are balanced within required tolerance.
- Viscosity, as mentioned, is main source of o/l tripping. The designer should have considered this requirement during sizing of motor/drive.
thanku for give me smart answer.i solved problem thriugh your help
problem of tripping at start explained very well. However, I am getting tripping signal when the motor is switched OFF. Kindly explain deceleration settings required in the soft starter and its logic.
THANK YOU.