Soft starter plays an important role in ensuring the stability of power system.It's actually simple.The voltage of thyristor control pole is adjusted by microcomputer, and then the size of thyristor conduction Angle is adjusted, so as to realize ac voltage regulation, which makes the motor input voltage gradually rise from zero to the preset function relationship, adjust the current size of the controlled motor, control the motor speed, and finally give the motor all the voltage.Realized to the power grid no impact current generation, gradually smooth start motor to reach the rated speed of the device.
The fault of soft starter is usually judged by voltage, resistance and replacement.
First, troubleshoot according to the fault code it displays.Look up its corresponding manual, will display the fault code and the fault code for comparison, to find the fault location and cause.The next step is to make real-time measurements and specific solutions.
Second, troubleshoot the problem in the usual way.Once there is a fault, we can not see the fault location, only according to the principle and the physical wiring diagram to find the fault area.The primary circuit, the rear control circuit, and the main circuit check whether the voltage of the power input line is normal, then whether the voltage of the power supply terminal is normal, whether each contact is normal when the coil voltage of the contactor is normal, and whether the insulation test of the three-phase power supply is normal.After checking these parts, if there is no fault, check in the control loop, the control power, button contacts, soft starter output contacts, etc.
For example, a high-power squirrel-cage motor cannot be started normally when the start button is pressed again after normal shutdown.There is no power in the coil of the intermediate relay measured by an electric pen, and there is no power in the output contact of the measurement soft starter, indicating that the output contact is not closed, so the device cannot start normally.Analyze the reasons;Since the start and stop of the motor must make the intermediate relay on or off, it is likely that the arc burns the relay contact inside the soft starter, resulting in poor contact and open circuit fault.The solution is to replace the same soft starter.For example, the contact of the internal relay of the soft starter is burned by arc. The first is that the intermediate relay used by the external is inductive load. The second is that the contact of the internal relay of the soft starter is burned by arc only after it has been used for a long time, resulting in poor contact.