Universal Mains voltage Power Soft Start Circuit for mains power transformers. It allows soft-start with limited inrush current to avoid damage to electrical mains circuit and mains fuse trip during transient overcurrent, when high capacity filter capacitors from the secondary side of the mains power transformer are charging.
It uses a Low-Power SMPS instead of a mains transformer, which offers several features unachievable with the mains transformer: Universal mains voltage compatible; provides one 12V aux. output with up to 1A; very low stand-by power consumption, <0.1W in idle mode, no load on Aux. or up to 0.45W in idle mode with 20-25mA load on aux. output. It is compatible with the latest power saving regulations which impose <0.5W stand-by power consumption.
It uses one large, industrial grade Power Resistor with large surge current capability. It also has remote function which allows to connect or disconnect the transformer using an external provided logic signal. It can use momentary push-button as Power ON/Off switch instead of older type switch.
It can be supplied within a wide mains voltage range, 85-260V AC or even with DC, 140-360V DC. Note that the relays can only switch Off AC voltage up to 250V AC or DC voltage up to 30V DC.
For more information, please read Power_SoftStart_v4.