Scroll will not start

[Snoring Beagle]

I have just replaced a 3 phase scroll. The small one of three on a 80 ton common return chiller condenser. Job went well. Charged Unit on the high side and started things went fine until the new compressor was staged on.

Instantly the breaker trips for the new one.

I eliminated the other causes and the problem is that brand new Trane compressor. I find it hard to believe but believe I must, I can't remember when I had a Bad compressor right out of the box.

Reversed rotation still won't start switched back, no go.

I let it sit overnight and try the next day, same results. So I do some research on the web and notice "Axial Sealing".

Any one ever dealt with this situation? We do have another coming as well as a couple of 15 ton scrolls on the way for the other units.

[Kraeusen]

Sometimes the mailman drops boxes. If you open a box and suction or discharge stubs are bent, always ohm out a compressor. No sense installing a grounded compressor, it does happen. How does this one ohm out?

[jayguy]

meg all of them i say!!! this is the exact reason why. sorry about your (bad) luck. it does occasionally happen.

good luck.

[Snoring Beagle]

Sometimes the mailman drops boxes. If you open a box and suction or discharge stubs are bent, always ohm out a compressor. No sense installing a grounded compressor, it does happen. How does this one ohm out?


It Megged out fine!

It shows every indication of locked rotor.

When I reversed it it sounded like it rotated one or two revolutions. Loudly!

Switched back same thing. Trips fast, the peak hold meter will register only 13 amps.

[REFERJMAN]

you didn't say why you had to change comp out? but how is your power at new comp? not sure what model of trane chiller it is but what does your contactor or starter look like are you getting all 3 Phases at new comp?

[John Culpepper]

I had a similar situation where the wire going to the line side of the contactor one had burned almost all the way through. There was enough of it left for me to get power at the contactor but not enough for the load. I've also had a couple that for no reason were bad out of the box. Best of luck,
John

[jimbob73]

By everything you said, I think I would swap breakers to be sure it isn't the breaker. I have seen quite of few breakers on these units that have weakened and trip well below must hold trip amps on compressor start up. You tried reversing rotation and the compressor was loud. Reversed rotation is louder then normal. With your meter only catching 13 amps with max hold ON during compressor start then why is the breaker tripping?
The breaker hold trip amps for a trane 460 v 15 ton compressor is something like 35 amps and even higher for 208/230 v. I think that is an indication that the compressor is not locked and the problem is the breaker, shorted windings, or wiring.

[zonemech]

Sounds like the possibility of single phasing, I had a situation where I was called to a job where another tech had changed out a bad compressor on a 40 T York condensing unit.
Only to find the same thing was happening (LR).

I found that one of the contacts on the contactor was burnt in half causing the unit to single phase.

[Airmechanical]

Sounds like the possibility of single phasing, I had a situation where I was called to a job where another tech had changed out a bad compressor on a 40 T York condensing unit.
Only to find the same thing was happening (LR).

I found that one of the contacts on the contactor was burnt in half causing the unit to single phase.

i had a tech call me to pick up a 10h.p. evap motor to replace

i showed up to the job with the motor, before i lugged the heavy motor up to the roof

he said the motor was locked, i spun the rotor it was not locked

i checked and showed him it had a bad fuse:mad:, replaced fuse, no new motor needed!



.