In transformers with dual primaries and secondaries, do I need to hook up both?
• YES, even though one primary (or secondary) winding may be all you need from the look of the schematic and/or specs, the unit was designed to run ALL windings. Example – you have a dual primary unit for 115/230VAC operation. You have 115VAC power, you must hook BOTH primaries in parallel (make sure you connect them in phase). • If you try to use only one primary (or secondary), the unit will probably overheat and voltage regulation will be poor. • Link here to our hook up explanations.
