For economical general usage, this is the preferred method of using a transformer with any thyristor power control unit. The SCR control can usually accept virtually any AC voltage input: simply wire the SCR control’s transformer to the conventional voltage on the primary, so that whatever maximum load voltage is required can be easily provided by the transformer secondary in front of the SCR unit.
For example, cutting or sealing plastic sheet or plastic foam is often done easily by heating nichrome wire and using a wire frame to cut plastic blocks out to any given size. The 1 to 5 foot lengths of wire, however, require low AC voltages to keep from burning up the wire. Worker safety considerations also require low voltages on the unprotected wires.
A thyristor unit connected to a buck/boost type transformer’s 12/24 or 16/32 VAC secondaries can easily control several hundreds of amps to many wires in parallel. The maximum current and/or number of wires is determined solely by the transformer’s secondary voltage.