What is a Soft Starter? How to Choose?

1- What is a Soft Starter?

Starting a motor directly over the mains is an undesirable type of starting in today’s technology. Because with the developing technology, it has become easier to give way to the motors. It is now very easy with the driver where speed adjustment is required, and with the soft starter in applications where speed adjustment is not required. In motor applications that do not require speed adjustment, the damages that may occur in the motor are reduced with soft start and soft stop at stop. In addition, we continue to protect the motor with advanced motor protection parameters. With these two ways of starting, the motor is thus not exposed to both electrical and mechanical effects compared to starting directly over the mains. Thus, the life of the motor is extended mechanically and electrically. In today’s article, we will examine the soft starter selection.

2- How to Choose?

What should we pay attention to when choosing a Soft Starter, which parameters are important for one, it would be right to decide by looking at what.

Many people decide by looking at the kW value and price, in fact, it is not right to choose this way.

Here are the things that need attention:

1. The current of the motor. (The Soft Starter to be selected should not be less than the motor current.)
2. The environment in which it will work is important. (If it is a hot place, it should be able to deliver the current required for the load at that temperature. That is, when the temperature increases, the current decreases, so temperature is one of the important parameters.)
3. It must have motor protection parameters. These must be carefully set and activated.
4. Does it include a by-pass system? (If it switches to by-pass after completing the start, no energy will be wasted on the Softstarter and the device will have a longer life. But the protections must continue.)
5. All three phases must have a thyristor block.
6. Pay attention to the type of load. If your load is a difficult load, such as a conveyor belt, it should be able to continuously deliver a current higher than the load current at 50 C.
7. Digital display and communication will inform you and communicate with your system.

When dimensioning Softstarters, the following criteria are considered. They must be designed to be all at the same time.

1. Temperature,
2. Max. Inrush current limit
3. Max. Departure time
4. Max. Number of departures. (within 1 hour)

There are 4 main parameters that can be adjusted in Soft Starter.

1. Inrush current limit,
2. Initial voltage
3. Departure time
4. Downtime.

The selected Soft starter must be capable of both soft starting and soft stopping.