The following analyzes the common faults and corresponding countermeasures of soft starters in daily applications:

1. During the debugging process, there is a phase loss fault reported at the start, the soft starter fault light is on, and the motor does not respond. The reason for the failure may be:

① When the starting method is electrified, the operation sequence is wrong. (The correct operation sequence should be to send the main power first, then the control power)

② When the power supply phase is missing, the soft starter protection action. (check power supply)

③ The output terminal of the soft starter is not connected to the load. (The soft starter can work normally only after the output terminal is connected to the load)

2. When the user is in use, the start-up is completed, and the bypass contactor does not pull in. The cause of the failure may be:

① During the starting process, the protection device malfunctioned due to the small setting. (Just reset the protection device)

② During debugging, the parameter setting of the soft starter is unreasonable. (mainly aimed at soft starters below 55KW, reset the parameters of the soft starter)

③ The control circuit is in poor contact. (check control wiring)

3. During the starting process, the user occasionally jumps the air switch. The reasons for the failure are:

① The setting value of the long delay time of the air switch is too small or the selection of the air switch and the motor do not match. (The parameters of the air switch are appropriately enlarged or the air switch is re-selected)

② The starting voltage parameter of the soft starter is set too high or the starting time is too long. (According to the load conditions, the starting voltage should be appropriately reduced or the starting time should be shortened appropriately)

③ During the starting process, due to the large fluctuation of the grid voltage, it is easy to cause the soft starter to issue wrong commands, resulting in an early bypass phenomenon. (It is recommended that users do not start high-power motors at the same time)

④ Start with full load when starting. (Reduce the load as much as possible when starting)

4. When the user uses the soft starter, there is no display on the display screen or garbled characters appear, and the soft starter does not work. The cause of the failure may be:

① During the use of the soft starter, the internal wiring of the soft starter is loose due to the vibration generated by the external components. (Open the cover of the soft starter and re-insert the display cable)

② The soft starter control board is faulty. (Contact the manufacturer to replace the control board)

5. The soft starter reports fault when starting, the soft starter does not work, and the motor does not respond. The cause of the failure may be:

① The motor phase is missing. (Check the motor and peripheral circuits)

② The main component thyristor in the soft starter is short-circuited. (Check whether the motor and grid voltage are abnormal. Contact the manufacturer to replace the thyristor)

③ The filter board is punctured and short-circuited. (You can replace the filter board)

6. When the soft starter starts the load, the start time-out phenomenon occurs. The soft starter stops working and the motor coasts to a stop. The reasons for the failure are:

① The parameter setting is unreasonable. (Re-adjust the parameters, increase the initial voltage and lengthen the time appropriately) ② Start with full load when starting. (The load should be reduced as much as possible when starting)

7. During the starting process, the current is unstable and the current is too large. Reasons may be:

① The indication of the ammeter is inaccurate or does not match the transformer. (replace with new ammeter)

② The grid voltage is unstable and the fluctuation is relatively large, causing the soft starter to malfunction. (Contact the manufacturer to replace the control board)

③ The parameter setting of the soft starter is unreasonable. (Re-tune parameters)

8. The soft starter starts repeatedly. The reasons for the failure are:

① During the starting process, the peripheral protection element acts, and the contactor cannot be pulled in, resulting in repeated starting of the soft starter. (Check peripheral components and wiring)

9. The overheating fault light is on when starting, and the soft starter stops working:

① Frequent starting, which leads to overheating, and causes the soft starter to overheat protection action. (The number of starts of the soft starter should be controlled to no more than 6 times per hour, especially heavy loads must be paid attention to)

② During the starting process, the protective element acts, so that the contactor cannot be bypassed, and the soft starter works for a long time, causing the protective action. (Check peripheral circuit)

③ Overheating protection is caused by over-heavy starting time for too long. (When starting, reduce the load as much as possible)

④ The parameter setting of the soft starter is unreasonable. If the time is too long, the starting voltage is too low. (raise the starting voltage)

⑤ The cooling fan of the soft starter is damaged and cannot work normally. (replace the fan)

10. SCR damage:

① When the motor starts, the overcurrent will break down the soft starter. (Check whether the power of the soft starter matches the power of the motor and whether the motor is started with load)

② The cooling fan of the soft starter is damaged. (replace the fan)

③ Frequent starting, high temperature will damage the thyristor. (Control the number of starts)

④ The filter board is damaged (replace the damaged components) The input phase is missing. There are many factors that cause this fault:

- Check whether the incoming power supply and the motor incoming wire are loose;

- Whether the output is connected to a load and whether the load matches the motor;

- Use a multimeter to check whether the soft starter module or thyristor is broken down, and whether their trigger gate resistance meets the requirements under normal conditions (usually around 20-30 ohms);

- Check if the internal wiring socket is loose.