This unit is a soft start module. It will reduce the starting inrush current to a reasonable value for a toroidal transformer. Because the transformer will draw a high current when it is switched on, in a few milliseconds, the magnetic flux will be stabilized, and at power on, rectifier filter capacitors are completely discharged, and act as a short circuit for a brief period of time.
The input power circuit has a few small value resistors (to limit the high current) in series with transformer primaries for first few hundred milliseconds, and then a relay contact will bypass the resistors (short circuit) after.
It works for most transformers or power supplies that have dual 120V primaries, and power ratings that are suitable from 500W to 1500W.
Before turning the unit on, please check the input voltage setting (factory pre-set to 120Vac). Remove the cover (power off) by removing the 2 screws on the top. A voltage select switch indicates the input voltage. You can slide the switch to your desired voltage.
If you blow the fuse, please check the load to make sure that it didn’t have short circuit before replacing the fuse.
We will install this item to your power supply when you order them together.
Vin = 120Vac / 240Vac 50/60Hz
Imax = 12A