Contactor Coil Resistance Values

No. (Or at least not necessarily.) For instance, a 24v coil on a big relay or contactor will typically have less resistance than such a coil on a small relay or contactor.

That said, it is sometimes hard to find out what the coil characteristics (e.g., va consumed) are, as they tend to be hidden among the miscellaneous data of various catalogs.

i assume you are aware that the inductance (in open and sealed conditions) is more significant than the resistance in AC coils. Here are the values for one Schneider contactor....

i have not come across such data in GE or other US catalogues. Anyway, i am curious why you need this data...can you please enlighten me? thanks.

I started a new job. I'm following someone that is no longer employed in my position. The coil in question controls circuit #1 which is a 3 phase compressor of a package AC unit. The coil control voltage is 240v. On one side of the coil I have 120v. On the other side is the protection side i.e. LP switch, HP switch...which only has 60v. Total voltage drop was about 160v across the coil. I think my predecessor put a 120v coil contactor in to make it work. It finally chattered enough to burn a pad on one of the contactors which single phased the compressor and smoked it. I have the old contactor and it reads about 150 ohms and the replacement is about 350 ohms. The replace was order by PT# off the old one. (I'm going by memory and its be several hours and a couple beers).

Thanks for the details.

i am not able to understand the 120V, the 60V and the 160V values that you mention... perhaps a single-line diagram would clarify. No matter....i don't think i am in a position to cheer you up. You may need a new contactor, since you say one contact (pad?) burnt and caused single-phasing.All contacts need to replaced in such a case.You may also need to incorporate a single-phase-preventor to avoid future problems. Furthermore, if the compressor motor is refrigerant-cooled, you need a verrrrry good overload relay...since the motor's locked-rotor withstand will be quite low due to the fact that the refrigerant is not moving !

Well they will be similar for the same type of task but unfortunately there are so many different amounts of mechanical work that each contactor must do to open and close a particular circuit. There is a good reason that there are so many different types of relays and contactors. At the same time I cannot think of a single contactor I've ever used that had a unique coil resistance.

Or just check the contactor data sheet.

If you are trying to troubleshoot this problem, the coil values really don't matter much. You only need to supply enough voltage and current to the coil.

If the reading of 120VAC was from ground to the coil A1 , 60 VAC A2 to Ground on the coil. If this is the case then you have one of two scenarios, 1 either you have a bad connection on the A2 line. or you are supplying 120 VAC to the coil.

In either case you appear to have a bad connection somewhere. Or it is possible the the control transformer is faulty.

Good luck!