Why did this happen? Lol

[vaporlock]

here is a funny story. I go out with a friend and fellow co-worker to assist in changing out two compressors in 2 different rooftop units, same buisness, the compresoors he said were warranty, turns out the restaraunt below, is new, hasn't even opened the doors yet, the units were new, 460volt 3-phase, electrician was doing work in the panel box in the store, caused reverse rotation on the scroll compressors, and ended burning up 3 of the four compressors, (they each had 2 stages) but the guy I was helping out only caught the 2, I'm thinking to myself, and this is Warranty? hah! oh yeah, I was also going to ask if there was any kind of devise the would prtect three-phase unit from single phasing, or running backwards if something was to go wrong, and an HVAC tech not be there to immediatly catch it.
Thanks

[Edited by vaporlock on 07-22-2004 at 11:10 PM]

[dchrbac]

Vaporlock...... Are you asking?
.....if there was any kind of devise the would prtect three-phase unit from single phasing, or running backwards if something was to go wrong.

[acjourneyman]

Sounds like BS to me, scrolls can run backwards,just won't pump.As far as single phasing goes the breaker would have tripped but compressors would be fine.We are missing something here!!!!!!!!

[gbfromsd]

running backwards . . no suction gas to cool 'em . . not good. They'll run backwards just fine - for awhile.

[mattm]

Originally posted by vaporlock
I was also going to ask if there was any kind of devise the would prtect three-phase unit from single phasing,
[Edited by vaporlock on 07-22-2004 at 11:10 PM]

It's called a phase guard. Any electrical, hvac, or motor supply house will have them. You can get them in manual or automatic reset.

[stevehvac]

Originally posted by mattm

Originally posted by vaporlock
I was also going to ask if there was any kind of devise the would prtect three-phase unit from single phasing,
[Edited by vaporlock on 07-22-2004 at 11:10 PM]

It's called a phase guard. Any electrical, hvac, or motor supply house will have them. You can get them in manual or automatic reset.

Yep a phase monitor will protect the units from several types of electrical issues but they are $100 each. I use them at malls they seem to have power issues a lot. I wouldn't install them on everything just incase someone reverses the power though.

[weezer]

Dear Vaporlock:
Yes, scrolls can run backwards for short periods of time. However, extended reverse rotation will cause mechanical failer due to loss of lubrication or electrical failure due to ground windings. I saw this same situation happen at a resturaunt. Seems a sparky came and did some electrical work on panel in the kitchen and single phased two 15 ton Carriers packaged units with Carlylses. It was a real mess. The other guys are right about phase monitors. I put them anywhere suspicious on units bigger than five tons. It is definately cheaper to install an 85 dollar Phase monitor than do a 1500 dollar or worse compressor replacement. But I can do that because of full maintenance contracts. I do not know what your situation is. Good luck. Weezer.

[hvacdoctor]

I have been asking this question for a while now? Brand new units with scroll compressors were started up by installer and ran fine. Then with in the year of warranty coverage the phases get reversed somehow. This causes reverse rotation and compressor damage and your on the line to fix the problem under warranty. #1 how do you prove reverse rotation caused damage and what if they fix the phases before you get there but the damage is done. Catch 22 on scrolls if you ask me. They need to come up with an anti reversing control or safety to prevent reverse rotation on these compressors. THis is my only problem with 3 phase scroll compressors....

[Edited by hvacdoctor on 07-23-2004 at 11:25 AM]

[R12rules]

Originally posted by hvacdoctor
I have been asking this question for a while now?

They need to come up with an anti reversing control or safety to prevent reverse rotation on these compressors. THis is my only problem with 3 phase scroll compressors....

Somebody like Supco, (sealed units parts company), would be very interested in learning we have an issue to be solved.
That is all they do anymore.

A black box which has a pressure transducer attached to the refrigerant line and monitors the voltage to the compressor.

1) compressor has power. Yes. Compressor has pressure differential. Yes. Then allow system to continue to operate.
If No pressure when Yes on power, shut down down and wait 60 minutes.

Very simple.
It would be simular to a Sentronics control.

[ericnyc]

reverse phase relay

[william antley]

I have been noticing on all the new Carrier three-phase equipment we are installing, there is a built-in phase monitor. If the power is phased incorrectly or single phasing, the condensing unit will not energize. Some of our apprentices have been caught by this and I've had to help them. Usually it's been loose wire connections causing single-phasing but, the monitor protected the unit.
I wonder if any other manufacturer is installing phase monitors in their new equipment? It may make our lives a little easier if they did.

[Chillermec]

I suggest 2 items, 1, get a phase sequence indicator ( tool ) to verify the phase sequence at start up. 2, I like the ICM 450 phase monitor which is programmable, and can be applied on 208 or 460 volt systems. It will protect against phase reversal, unbalance, single phase, and under / over volts. It has a fault history also. Both are avaiable at W.W. Grainger, or, others. The monitor can be auto or manual reset.

[Edited by Chillermec on 07-31-2004 at 08:54 AM]

[shovelhead]

ICM makes a resonably priced phase monitor, does reversal, phase loss, high and low leg. It has a LCD display and a control circuit with a double pole relay. The good thing is it'll work with a wide range of voltages. It also monitors line and load voltage. As for scrolls running backwards, they have lubrication problems running backwards, they won't pump refrigerant properly and make a louder than normal noise. Phase meters are only about $100. I never understood why electricians don't carry them.