Proximity wiring for limit switches, safety relay and a contactor

[CharlieRam]

Yes my bad

No problem, i appreciate the help :)

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[CharlieRam]

Question for anyone that knows, i have now bought a contactor to control the 240v side or the toroidal power supply. The coil is 24v and it is wired up and functioning but it seems to get very hot! I have disconnected the 240v to verify its the coil side that is hot and it is so my question is whether this is normal? I first noticed it when I smelt it!

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[john swift]

It should not run that hot
double check your not connecting 24V DC to a 24V AC coil !

which contactor do you have ?

John

[CharlieRam]

I didn't even think you'd get a a 24v a.c. coil! Hmm...mayve it is now that I've had another look, it says 24v 50hz. :(

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[Clive S]

Yes I have seen that before. 😡

[john swift]

The resistance of a 24V AC coil is too low to limit the current to a safe level when its connect to 24V DC

Connecting a DC coil to AC will reduce the current and may not pull in the contactor
and the eddy currents in the magnetic core heat the core
(usually laminated cores for AC & solid for DC)

Its a few year ago I last bought contactors from RS conponents

The klockner moeller contactors I bought had 48V dc coils ,
I clipped 2 contactors onto a mechanical interlock for 3 phase motor direction control
(to make it impossible for both contactor to make a connection )

From what I remember the coils available was
24V DC , 48V DC , 24V AC , 48V AC , 110V AC , 240V AC or 420V AC

John