Common failures and solutions for soft starters

- Jul 19, 2019-

Starter (also known as soft starter, motor soft starter), soft starter is a set of motor soft start, soft parking, light load energy saving and a variety of protection functions in one of the new motor control device, foreign known as SoftStarter. Its main composition is to string the three opposite parallel gate tube and its electronic control circuit between the power supply and the charged motor. Using different methods, control the on-on angle of the three opposite parallel gate tubes, so that the input voltage of the charged motor varies according to different requirements, different functions can be realized.

The following analysis of the failures and countermeasures that commonly occur in the daily application of the soft starter:

1. In the commissioning process, there is a failure of the starting report, soft starter fault light, the motor did not respond. The cause of the failure may be:

(1) When the starting mode is live, the order of operation is incorrect.

(The correct order of operation should be first to send the main power supply, the power supply should be sent back to control power supply)

(2) Power supply is out of phase, soft starter protection action.

(Check the power supply) (3) The output end of the soft starter is missed the load. (Soft starter sits only after output is terminated on load)

2. The user in the process of use of the start-up, bypass contactor sucking phenomenon.

The cause of the failure may be:

(1) During the start-up process, the protective device is in mistaken motion due to the small adjustment.(Re-fix the protection)

(2) During debugging, the parameters of the soft starter are not set properly.(Primarily for soft starters below 55KW, re-set to the parameters of the soft starter)

(3) Poor contact of the control line. (Check control line)

3. The user in the starting process, there are occasional air-jumping switch phenomenon.

The causes of the failure are:

(1) The calibration value of the air switch for long delay is too small or the air switch selection and motor are not matched.(The parameters of the air switch are moderately amplified or the air switch is re-selected type)

(2) The starting voltage parameters of the soft starter are set too high or the starting time is too long.(The starting voltage is appropriately reduced or the starting time is appropriately reduced depending on the load)

(3) In the starting process due to the power grid voltage fluctuations are relatively large, easy to cause the soft starter to issue the wrong instructions, the phenomenon of advance bypass.(It is recommended that the user do not start high-power motors at the same time)

(4) Full load start-up at start-up. (Minimize load at start-up)

4. The user in the use of soft starter when the display does not show or appear garbled code, soft starter does not work. The cause of the failure may be:

 (1) The vibration caused by the external component during of the soft starter during use causes the internal wiring of the soft starter to vibrate.(Open the face cover of the soft starter and plug the display connection back into the tension)

(2) Soft starter control board failure. (Contact the manufacturer to replace the control board)

5. Soft starter in the start time fault, soft starter does not work, the motor does not respond.

The cause of the failure may be:

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

(2) The main component of the soft starter, The SCR, is short-circuited. (Check the motor and the grid voltage for anomalies.)Contact the manufacturer to replace The SCR)

(3) The filter plate breaks through the short circuit. (Replace the filter plate)

6. Soft starter in the starting load, the starting time-out phenomenon. The soft starter stops working and the motor stops freely.The causes of the failure are:

 (1) The parameter setting is unreasonable.(Re-adjusting the parameters, the starting voltage is appropriately raised, the time is appropriately lengthened)

(2) Full load start-up at start-up. (The load should be reduced as much as possible when starting)

7. In the start-up process, the current is unstable, the current is too large.

Possible reasons may be:

 (1) The current meter indicates an inaccurate or does not match the transformer.

(Replace a new current meter)

(2) The voltage of the power grid is unstable and the fluctuation is relatively large, causing the soft starter to act incorrectly.

(Contact the manufacturer to replace the control board)

(4) The soft starter parameter setting is unreasonable. (Re-adjusting parameters)

8. Soft starter appears repeated start.

The causes of the failure are:

(1) Peripheral protection element action during the starting process, contactors can not suck together, resulting in a repeat start of the soft starter. (Check peripheral components and wiring)

9. In the start-up of the overheating fault light is on, the soft starter stops working:

(1) Frequent starting, resulting in excessive temperature, causing the soft starter to overheat protection action.(Soft starter starting times to be controlled no more than 6 times per hour, especially heavy load must pay attention)

(2) In the starting process, the protection element action, so that the contactor can not bypass, soft starter long-term work, causing protection action.(Check peripheral circuits)

(3) Too long load start time causes overheating protection.(Reduce the load as much as possible when starting)

(4) The parameters of the soft starter are not adjusted properly. The time is too long and the starting voltage is too low.(Raise the starting voltage)

(5) The cooling fan of the soft starter is damaged and does not work properly. (Replace fan)

10. SCR damage:

(1) When the motor is started, the overcurrent breaks through the soft starter.(Check that the soft starter power matches the power of the motor and whether the motor is started on an on-board basis)

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

(3) Frequent starting, high temperature will be damaged by silicon.(Control the number of starts)

(4) The filter plate is damaged (replace the damaged component) input is not phase-out, causing this fault there are many factors:

- Check the inlet power supply and motor inlet line for looseness;

- whether the output is loaded and whether the load matches the motor;

- Use a universal table to detect whether the module or SCR breaks through the soft starter and whether their trigger gate resistance meets the normal requirements (generally around 20-30 euros); - Is the internal wiring socket loose?