Transformer on....

[mrcaptainbob]

Okay, so I have a 120/24 V transformer for an appliance. The 24V is activated by a separate switch for it's purpose. If the switch is off, does that transformer still draw any power? That is, if there's no load on the 24V side, is there still a current draw on the 120V side?

[HayZee518]

no there isn't. there's nothing to complete the circuit. whatever load the secondary sees, the primary sees. the primary and secondary is coupled together by the iron core that is common to both windings, the primary and secondary. not that it means anything but there is a 180 degree phase shift across the transformer.

[Speedbump]

Not to say your wrong HayZee, but when a wall wart is plugged into the wall and the load has been taken off the 24 volt side, why does the wall wart still feel warm? Some of them even buzz a little bit. There has to be some current consumed since it is a circuit. The Primary is a complete circuit all the time it's plugged in; isn't it?

[paul52446m]

Not to say your wrong HayZee, but when a wall wart is plugged into the wall and the load has been taken off the 24 volt side, why does the wall wart still feel warm? Some of them even buzz a little bit. There has to be some current consumed since it is a circuit. The Primary is a complete circuit all the time it's plugged in; isn't it?

The transformers we use on a furnace do the buss thing and they are warm, with no load on the 24 volt side, so i would think the same thing, that they are using some power to maintain that 24 volt even when the 24 volt is not being used?????? Paul