Soft starter for squirrel-cage motor

Abstract

The invention discloses a soft starter for a squirrel-cage motor. The soft starter comprises a motor main switch, and a failure switch and a control bypass contactor passive contact switch which are connected with the motor main switch, a reset switch connected with the control bypass contactor passive contact switch, a quick stop switch connected with the reset switch, a soft stop switch connected with the quick stop switch, a soft start switch connected with the soft stop switch, a public end connected with the soft start switch, a running signal switch connected with the failure switch, and a power interface connected with the running signal switch. The soft starter for the squirrel-cage motor not only has overload, overcurrent and phase failure protection functions, but also has reset, soft stop, and quick stop functions, and more comprehensively protects the motor.

Description

technical field [0001] The invention relates to a soft starter for a squirrel cage motor. Background technique [0002] The squirrel-cage three-phase asynchronous motor is the most widely used electrical equipment. The traditional starting methods include star-delta starting, auto-coupling decompression starting, reactor decompression starting, and Yanbian delta decompression starting. Stage decompression starts. Their common feature is that the control circuit is simple, but the starting torque is not adjustable, and there is a large inrush current during the starting process, which makes the dragged load suffer a large mechanical impact, and is easily affected by the grid voltage fluctuation. Once the grid voltage Fluctuation will cause difficulty in starting and even stall the motor. Several start-up methods during shutdown are instantaneous power failures, which will also cause severe grid voltage fluctuations and mechanical shocks. Therefore, a soft starter device is...

AI Technical Summary

Problems solved by technology

Their common feature is that the control circuit is simple, but the starting torque is not adjustable, and there is a large inrush current during the starting process, which makes the dragged load suffer a large mechanical impact, and is easily affected by the grid voltage fluctuation. Once the grid voltage Fluctuation, it will cause difficulty in starting, and even cause the motor to stall

Several start-up methods are instantaneous power failures during shutdown, which will also cause severe grid voltage fluctuations and mechanical shocks

Therefore, a soft start device is needed to slowly load the motor. Most soft starts on the market only have overcurrent, overload, and phase loss protection functions, which cannot meet the needs of industrial development.

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