Transformer and voltage range theory

[Skiroy]

Okay Im a noobie. My understanding was that the primary side of the transfomer was what you feed to the transformer and the secondary is what the transformer outputs.

Primary equals input of 240V and secondary equals output on 120V.

Well my boss today, which I dont have the most confidence in looked at a transfomer that its label siad the primary was 480V and the Secondary was 208V.

He told me that the transformer converted 208V to 480V,but I thought it was vice versa.

1.So is he wrong or can you take a transformer and supply voltage to the secondary and step up voltage and use the primary as the output?

2. And a unrelated question, They have a motor rated for 220V running on 240V voltage. I know the voltage range is +- 10% for whats on the motors namplate. So that means the max upper range for the motors is 242V. So is this cutting it too close?

[Al_The_Man]

For the most part you can feed a transformer in reverse, in some cases however there are compensation windings on the secondary for some transformers up to a certain size which can affect the reverse output, it could be that someone installed this one to operate in reverse.
Motors and transformers are fairly tolerant items and running the motor at 240 should be OK.
Al.

[Skiroy]

Originally Posted by Al_The_Man For the most part you can feed a transformer in reverse, in some cases however there are compensation windings on the secondary for some transformers up to a certain size which can affect the reverse output, it could be that someone installed this one to operate in reverse. Motors and transformers are fairly tolerant items and running the motor at 240 should be OK. Al.

So if I have a thermal over load relay on the motor contactor that keeps triggering, then either the motor is bad(pulling too much amps), or supply voltage is unbalanced?

Motor cant be too small because it came with the AC dryer. And its possiable that it may be getting too hot because its in a hot location outside. But that would not cause the motor to pull more amps and trip the contactor overload,correct?

I could see if the motor had a thermister or thermocouple built in it that the motor would shut off itself, but wouldnt the contactor still remain engaged and the overload would not have to be reset, would it?

[Al_The_Man]

I take it this is a three phase motor?
I would take a clamp on ammeter current reading of all three phases.
Check the motor FLA on the name plate and see what the overload rating is on the contactor.
Al.