How to Extend the Life of Soft Starters

Soft starters are very reliable and durable as long as they are used properly and within the range specified by the technical conditions of the device. It requires little maintenance, but the following items need regular inspection and maintenance to maximize its effectiveness and prolong its service life.

fig.-XiChi CMC-MX Soft Starter in GCK Switchgear

When maintaining the soft starter, professional and technical personnel must be required to operate or operate under the guidance of professional and technical personnel. Maintenance of the soft starter can be done with the machine removed or directly on the switchboard.

However, when maintenance is performed directly on the switchboard, the main power supply and control power supply should be disconnected first, and the power distribution box with the power distribution switch of this circuit should be locked. At the same time, obvious warning signs should be set on the distribution box to prevent other people from accidentally closing the distribution switch, resulting in electric shock accidents.

1. Cleaning of soft start equipment

Equipment should be checked regularly for cleanliness. If there is too much dust and dirt, it will reduce the insulation level of the soft starter, which may cause the following hazards:

1. The primary circuit is creeping and arcing, causing serious faults of equipment short circuit.

2. The secondary circuit has leakage, short circuit, and control failure.

3. The thermal resistance of the radiator increases, and the temperature rise of the thyristor increases, resulting in thermal protection action or damage to the thyristor.

Here's how to clean your equipment:

1. Use a clean and dry brush to gently brush off the dust inside the device.

2. Compressed air can be used to remove the dust on the printed circuit board, and the stubborn dirt can be gently wiped off with an alcohol cotton ball.

2. Drying of soft starter condensation

Always check the inside of the device for condensation in humid climates or in autumn, when condensation is likely to occur. If condensation occurs, the insulation level of the soft starter will be reduced, and the possible hazards are:

1. The primary circuit is creeping and arcing, causing serious faults of equipment short circuit.

2. The secondary circuit has leakage, short circuit, and control failure.

3. Add the corrosion of metal parts.

Drying methods are as follows:

1. Dry with a hair dryer or a heat gun.

2. A dehumidifier can be used to dehumidify the power distribution room.

3. In the case of severe condensation, heating and dehumidification equipment should be installed in the power distribution cabinet with soft starter.

3. Maintenance of soft starter ventilation and cooling system

For soft starters equipped with cooling fans, regularly check whether the air duct is blocked and whether the fan is running well. If the air duct is blocked or the fan is damaged, the thermal resistance of the radiator will be increased, and the temperature rise of the thyristor will be increased. Long-term operation will cause the soft starter to overheat protection action or damage the thyristor.

If the air duct is blocked, clear the blockage in the air duct in time to keep the air duct unobstructed. In the soft starter, the fan is a consumable item. If the fan does not rotate or rotates obviously slowly, it should be replaced. Generally, the fans used in soft starters are standard products, which are sold in the market. Users can replace them by themselves or contact the supplier to replace them. Please note that the size, rated voltage and ventilation capacity of different types of fans are different, and the same type of fan should be replaced or a fan of the same size, rated voltage and not less than the ventilation capacity of the original fan should be replaced.

4. Maintenance of connectors in soft-start equipment

The controller and other components in the panel cabinet should be checked regularly to see if all connections are tight. If the connector is loose, it may cause the following hazards:

1. The connection point is heated, which may cause ablation or fusing at the connection point in severe cases, the adjacent electrical components are damaged due to excessive heat, and the adjacent insulated wires are heated and the insulation accelerates aging.

2. The control circuit is in poor contact, causing various unusual failures of the soft starter.

5. Maintenance of wires in soft start cabinet

Wires have a great relationship with the safety of equipment use. Regularly check the main circuit and control circuit wires in the controller and the panel cabinet to check whether the wires are aging, carbonized, cracked, damaged, etc. Hazards that may result from damaged wires include:

1. The primary circuit is creeping and arcing, causing serious faults of equipment short circuit.

2. The secondary circuit has leakage, short circuit, and control failure. As long as the phenomenon of aging occurs, no matter how serious it is, the wires should be replaced in time.

6. Changes in the usage environment of the soft starter

If the operating environment around the equipment has changed greatly, corresponding measures should be taken. For example, when the dust in the use environment increases to a certain extent, the sealing and air filtration measures of the power distribution cabinet should be taken; when corrosive gas occurs in the use environment, anti-corrosion and insulation measures should be taken.

7. Components in Soft Starters

1. Clean the main and auxiliary contacts of various electrical components with fine sandpaper at regular intervals.

2. Check whether the air gap of the vacuum contactor meets the requirements every year according to the manufacturer's technical manual.

3. The contacts and armatures with serious wear should be repaired and replaced.

4. Devices such as starting contactors (relays) should be replaced regularly.

5. Check whether there are traces left after overheating, or damage to the device.

8. Soft Starter Functional Protection Check

The action sequence and setting value of each protection device should be checked every other year to ensure correctness.

9. Flow equalization check for Soft Starters

For soft-starting devices with large power and multiple branches working in parallel, the flow equalization should be checked regularly, and the flow equalization coefficient should be above 0.7. Otherwise, check whether the connection between the busbar and the fast fuse is loose and whether the characteristics of the thyristor are deteriorated.

10. Inspection of potentiometers, buttons and operating appliances 

Pay attention to check whether there is poor contact or disconnection. Use pure gasoline or alcohol to clean the sliding piece of the point device with poor contact, and replace the operating electrical appliances with serious corrosion and wear in time.