“Soft Start” is a function allowing one to gradually turn on an electronic device’s output until it reaches 100% output. This is commonly used in motor applications, in which a starting current value is suppressed to allow a smooth startup.
The above time chart example shows Omron’s G3J-T series Solid State Contactor in 3-phase motor applications. You may find that
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When the devices receives the signal from “Operation Indicator lit Monitor Output”, the load current will start to ramp up.
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Due to the device’s soft start characteristics, the load current will be controlled to ensure that the output remains within the rated current value according to the application.
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For some advanced controllers, the soft start time depends on the load characteristics (e.g. inertia and friction factor) in addition to the starting torque, ramp-up time and ramp down time. Therefore the soft start will not excessively extend due to the ramp up time being increased.