There are three differences between bypass soft starter and online soft starter: composition structure, economic benefit and operating life.

1、Structural differences:
When a bypass contactor is installed outside the bypass soft starter, the starting cabinet can work normally. The current flows through the bypass contactor when the motor is running, and the current flows through the soft starter only when the motor is started.

2、Cost difference:
Online soft start cabinet does not need to be equipped with bypass contactor, from the cost point of view, online soft start cabinet than non-online soft start cabinet price will be slightly cheaper. The extra bypass contactor determines that the price of the bypass soft start cabinet is higher than that of the online soft start cabinet.
The reality is that many manufacturers’ bypass soft starters are cheaper than online soft starters, which is determined by the cost of thyristor. Although external bypass contactors require contactors that match the rated current of the motor, in-line contactors do not.
In general comparison, the cost of the bypass soft starter plus contactor is generally lower than that of the online soft starter.

3、life difference:
The market has proved that bypass soft starters are more durable and less prone to damage, and there are ATS48 soft starters that have been used for 12 years, and the external bypass used is still working normally. The basic reason for the durability of the on-line soft starter is its own power loss. Because the silicon component itself has a pressure drop, the diode is a very simple silicon component, it generally has a pressure drop of about 0.6V, and the thyristor used in the soft starter, the pressure difference between the inlet and outlet of the soft starter is the culprit of its own power loss.
The thyristor of the on-line soft start cabinet is always in the working state, and the service life of the bypass soft start cabinet is relatively longer under the premise of the same power and quality.