Relay coils blowing/shorting

[hmmmnz]

Ive got a problem with relay coils shorting out.

24v DC coils, measure 1k ohm
As soon as I apply voltage they short out and put the power supply into protection

System has been working fine, until a detector went into safety and opened the circuit cutting the supply to the relay's coil.
Protection closed but now every relay that gets plugged in, shorts out. 0 ohm across the coil.
I'm struggling to understand.

Any hints appreciated

 

[hmmmnz]

Right,
Got it. It appears that whomever has ordered the spare relays has ordered ones that have the 24+ and 0v the opposite way around from the originals.

Something to look out for, that's for sure.

Cheers forum for being a sounding board. Sometimes that's all you need

 

[brianmoooore]

I presume that the coils have a built in diode to supress back EMF.

 

[Lucien Nunes]

I was going to say 'check the polarity of the diode' and go back to sleep thinking I had done one final useful thing for the evening when my phome came out of.the time warp it had been stuck in since 10pm and revealed you had already worked this out.