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What are the specific protection functions of the soft starter?

Dec 24, 2020

What are the specific protection functions of the soft starter?

①Overheat protection


   After starting the motor, the soft starter will calculate the temperature rise of the motor based on the rated current and the actual working current. When the temperature of the motor exceeds the preset limit temperature, the soft starter will immediately cut off the circuit and implement overheat protection.


Some motor control circuits use PTC resistors for direct overheating protection. The PTC resistors are embedded in the stator windings of the motor. When the temperature of the windings rises, the resistance of the PTC resistors gradually increases to implement overheating protection for the motor.

② Phase failure protection


When a certain phase of the motor power supply is low or open, the three-phase current will be unbalanced. When the unbalanced current reaches the trip level preset by the soft starter and exceeds the trip set delay, The motor stops running and implements phase failure protection.


  ③Underload protection


  Underload protection is also undercurrent protection. When the motor is working under full voltage, the underload protection function of the soft starter monitors in real time. If the motor current drops suddenly, exceeds the underload trip setting range, and exceeds the trip setting delay, the motor stops running , Implement underload protection.


  ④Overload protection


   Overload protection is also overcurrent protection. When the motor is working under full voltage, the soft starter's overload protection function monitors in real time. If the motor current suddenly rises, exceeds the overload trip setting range, and exceeds the trip setting delay, the motor stops running and implements Overload protection.


  ⑤Overvoltage protection


   When the input voltage of the motor control circuit suddenly rises, exceeds the overvoltage trip setting range of the soft starter, and exceeds the delay setting of the trip, the motor stops running and implements overvoltage protection.


  ⑥Under voltage protection


   When the voltage of the motor power supply line drops significantly or disappears due to a fault or other reasons, the undervoltage protection function of the soft starter will act to control the motor to stop running and implement undervoltage protection.


  ⑦ Stall and stall protection


   When the motor is blocked or stalled, the current that the motor bears increases, the torque increases, and it is easy to cause damage to the motor. When the soft starter detects that the motor is blocked or stalled, it controls the motor to stop running and implement the blocked or stall protection.


  ⑧Soft starter's own overheating protection


   There is a thermal sensor inside the soft starter to monitor the temperature of the thyristor. When the temperature of the thyristor reaches the rated temperature, the soft starter controls the thyristor to cut off and implements overheat protection.