Ground short ?

[AddMore22]

Compressor ----
Copeland
3 Ph
560 Volt
60Hz

Equipment
10 ton split custom made (marine)......

Story.....

I fly 120 miles in the gulf of Mexico to work on a solenoid valve .... Change it.... All is good....
I pulled a vac to 700 microns ....
Dumped recovered gas back in (on both sides) and when I went to start it tripped main breaker. So I took wires off peckerhead and checked to ground. And alas.... Grounded. So.... Does anyone know why? It worked before.... I didn't turn anything on while in vac ....

[BillDuffy]

Compressor ----
Copeland
3 Ph
560 Volt
60Hz

Equipment
10 ton split custom made (marine)......

Story.....

I fly 120 miles in the gulf of Mexico to work on a solenoid valve .... Change it.... All is good....
I pulled a vac to 700 microns ....
Dumped recovered gas back in (on both sides) and when I went to start it tripped main breaker. So I took wires off peckerhead and checked to ground. And alas.... Grounded. So.... Does anyone know why? It worked before.... I didn't turn anything on while in vac ....

When you dumped the recovered gas back in both sides was it liquid?

[DNMechanical]

I think u charged liquid in suction side. compressor was probably compressing liquid refrigerant.

[Six]

Topping off the compressor sump with liquid will trash your valves but I doubt it caused an immediate short. Is that for a drive house ?

[valdelocc]

Topping off the compressor sump with liquid will trash your valves but I doubt it caused an immediate short. Is that for a drive house ?

Besides trashing the valves, the liquid refrigerant washes the oil from the sump, bearings run dry till the rotor collapses shorting the stator to ground. been there,done that.

[Six]

Besides trashing the valves, the liquid refrigerant washes the oil from the sump, bearings run dry till the rotor collapses shorting the stator to ground. been there,done that.

On a scroll ? I see what you're saying but that specific scenario is limited to semi hermetics.

You still wash the bearings no doubt but not in a millisecond causing instant short to ground.

[valdelocc]

On a scroll ? I see what you're saying but that specific scenario is limited to semi hermetics.

You still wash the bearings no doubt but not in a millisecond causing instant short to ground.

scrolls need oil too, they are more tolerant to flooding cause the pumping mechanism, specially the compliant scrolls.
There is a misconception about compressors failures due to slugging/flooding, the old "you cant compress liquid" is only a small part of the problem, lack of lubrication is what makes them fail most of the time, it does not happens in a millisecond, depending on the system it may take days or just minutes.

[Six]

scrolls need oil too, they are more tolerant to flooding cause the pumping mechanism, specially the compliant scrolls.
There is a misconception about compressors failures due to slugging/flooding, the old "you cant compress liquid" is only a small part of the problem, lack of lubrication is what makes them fail most of the time, it does not happens in a millisecond, depending on the system it may take days or just minutes.

I'm aware of all of that.

What I meant was the crank on a Carlyse 06E ( FOR EXAMPLE ) obviously runs parallel to the bottom of the unit. So if the bearing in the end bell gets washed out then it allows enough play for physical contact between the rotor and windings.

So you get get a short to ground.....boom

The windings and rotor on a scroll are obviously vertical.

Plus in the last 20 years I've pulled my fair share of heads off of semi-hermetic compressors to see damage from liquid slugging in the form of holes in the top of pistons or broken cranks.

[Six]

Was the solenoid liquid valve leaking or just inoperable ?

Did you check it before you replaced the solenoid valve ?

[AddMore22]

Was the solenoid liquid valve leaking or just inoperable ?

Did you check it before you replaced the solenoid valve ?

It was just leaking .....
It has a receiver.
Not worried about liquid in suction
It was in a VFD house.

[Nuclrchiller]

What is a "VFD house" ? What kind of device interrupts power to the compressor ? Is it a contactor or something else ? What kind of crancase heater, if any ?

[AddMore22]

"VFD" - Variable Frequency Drive- its on a drilling rig.

It's a 3 phase 600 volt ... So no cap...

Crank case heater has been disabled prior this.

I guess my main question is this ...
Is there any way the insulation in the windings of a compressor be compromised due to a vacuum?

[Nuclrchiller]

I thought "VFD" probably meant Variable Frequency Drive, but what exactly is meant by "VFD house" ? EVERYTHING has VFD ? Including compressor ? I realise it has no capacitor, at least I've never heard of a cap used to interrupt power as a means of starting and stopping something, like a compressor... The reason I ask what does start and stop, or interrupt the power to, the compressor is to determine if it is a solid state device ( like a soft starter, or a VFD ). It seems unlikley that it would be anything other that a simple contactor on something this size, but I just wanted to rule it out.

[Six]

I thought "VFD" probably meant Variable Frequency Drive, but what exactly is meant by "VFD house" ? EVERYTHING has VFD ? Including compressor ? I realise it has no capacitor, at least I've never heard of a cap used to interrupt power as a means of starting and stopping something, like a compressor... The reason I ask what does start and stop, or interrupt the power to, the compressor is to determine if it is a solid state device ( like a soft starter, or a VFD ). It seems unlikley that it would be anything other that a simple contactor on something this size, but I just wanted to rule it out.

Its a seperate building on land and offshore rigs that houses all of the motor control, fuses, controls and VFDs for the DC motors on the rig.

High heat load and a critical part of any rig. You lose AC and the drives overheat and they have to stop drilling.

A multi million dollar operation is put on hold until you get the AC repaired.

Roughnecks and tool pushers looking at you sideways.

[Nuclrchiller]

Its a seperate building on land and offshore rigs that houses all of the motor control, fuses, controls and VFDs for the DC motors on the rig.

High heat load and a critical part of any rig. You lose AC and the drives overheat and they have to stop drilling.

A multi million dollar operation is put on hold until you get the AC repaired.

Roughnecks and tool pushers looking at you sideways.

Ohhh..., OK. Thanks.

[AddMore22]

Actually it's a 10 ton with 2 5 ton Copland scrolls. And one legs is always hot with the other two going in a contractor.

[Nuclrchiller]

Actually it's a 10 ton with 2 5 ton Copland scrolls. And one legs is always hot with the other two going in a contractor.

Was unit powered up ( even though not running ) during evacuation ?

[hvac69]

And one legs is always hot with the other two going in a contractor.

There is your problem if you had power to the unit while evacuating. Never pull a compressor under vacuum while windings are powered. Seen it on a job where a co worker suddenly had multiple DOA grounded compressors, went over his install and evac process and he was leaving the unit powered due to 2nd compressor. He hasn't had one since.

Never mind missed the one post mentioning lock out tag out

[AddMore22]

No.... Loto was in place during the evac.
(lockout tagout)

[Nuclrchiller]

No.... Loto was in place during the evac.
(lockout tagout)

That's good. And I'm sure you checked it with your meter, right ? Was it running when you got there ? If so, maybe it was just your bad luck to come across a near-failure looking for somebody to dump on.