What is the difference between soft start and hard start?

What is soft start and hard start

Soft start is step-down start, and hard start is direct start.

The soft start of the motor means that the motor uses a lower current and starts slowly when it starts. This starting method has a smaller impact and can reduce the load on the voltage regulator and control circuit, which is helpful for increasing the service life of the equipment. Soft start means starting with a buffer interval. That is to say, at the beginning of the motor start, the current setting must have a ramp process.

Hard start is direct start. Generally speaking, hard start means starting directly at rated current when power is turned on. Direct start (hard reset) exceeds the rated current of the motor. The production process of the motor itself and the structure bring many restrictions.

The difference between soft start and hard start

Soft start and hard start are two different starting methods in motor starting methods. The differences are as follows:

1. Starting method: Hard starting is a direct starting method for the motor, while soft starting is a starting method that gradually increases the voltage and current to gradually bring the motor into normal working state.

2. Starting current: Hard starting motors have a large current when starting, which may cause voltage fluctuations or turbulence, leading to failure or damage to other equipment. Soft starting can gradually increase the voltage and current, and the current is small when the motor starts, which has less impact on the power grid and is safer.

3. Equipment life: The impact and vibration of a hard-started motor at startup are large, which may cause mechanical stress to the motor and mechanical equipment, leading to damage and aging of the equipment. Soft starting can gradually increase the speed of the motor, reduce the mechanical stress and electromagnetic shock of the equipment, and thus extend the life of the equipment.

4. Startup cost: The cost of soft start equipment is higher than that of hard start equipment, but the current of soft start equipment is smaller during startup, which can reduce the load on the power system and thus save energy.

In summary, there are certain differences between soft start and hard start in terms of start-up method, start-up current, equipment life and start-up cost. The specific start-up method to be used needs to be selected according to actual needs. If a small start-up current and a long equipment life are required, a soft start method can be selected; if only the start-up cost and start-up time are considered, a hard start method can be selected.