The short answer is no. A soft starter does not reduce the running current of a device. It is designed to limit inrush current during startup but does not decrease the energy consumption of the motor once it reaches full operation. Running amps are determined by the motor's design and the appliance's operational requirements.
For example, while a soft starter for an AC unit can significantly lower the starting current — reducing the chance of tripping or overloading — the appliance will continue drawing the same amount of running current needed for its operation. Thus, while soft starter devices offer important advantages, reducing running amps is not one of them. This article explores the soft starter effects on running amps, and their potential benefits for equipment.
What is the amperage of a soft starter at startup?
The exact amp consumption with a soft starter depends on the size of the unit and the specific device model. Typically, a soft start device reduces inrush current by up to 70%. For example, this could lower a 60-amp startup current to approximately 18 amps, making AC units safer and easier to start, especially on smaller power sources.
When should you use a soft start device?
1.The motor power is relatively large.
It is generally recommended to avoid direct starting for motors above 7.5kW and instead use a soft starter. For motors above 30kW, the use of a soft starter is strongly recommended to reduce the impact on the power grid. For small-power motors such as below7.5kW, direct starting is possible if the grid capacity is sufficient. However, if there are requirements for smooth starting or equipment longevity, a soft starter can still be selected.
2.It is necessary to limit the starting current.
Soft starters can control the starting current to 2–3 times the rated current, which is much lower than the 4–7 times of direct starting. This effectively avoids grid voltage fluctuations and abnormal operation of equipment on the same line.
3.The load is sensitive to mechanical shocks.
It is applicable to equipment such as fans, pumps, conveyors, compressors, mixers, and crushers to avoid mechanical stress during start-up and shutdown.
