Dead Compressor - Why?

[airefresco]

I have a client who has a Frascold 3 phase compressor installed. The compressor is A17Y type R22. Recently a fault has developed where the main circuit breaker for the whole building trips when the compressor tries to start. It has been found that the fault is with the compressor and that is being replaced. We are now trying to find out what could of been the cause of the fault. The system is rather old and not installed to a good standard. It was found that the neutral wire supplying the coil on 3-phrase contactor was not connected properly (loose fit). Would this be a likely cause or should we look elsewhere for the fault? I would of thought that this would just cause the coil on the contactor to burn out, but I appreciate to hear your opinion.

Thanks
Paul

[thebigcheese]

is the compressor going to earth or is it seized causing high ampage

[monkey spanners]

If the poor neutral conection caused the contactor to switch on and off rapidly it would soon damage the compressor.

I would recommend you strip the old compressor and check for damage, look for mechanical wear, broken valves, scored bearings etc, and look at the windings to see if they are burnt, and if so evenly or just one or two of them.

Theres a bit of information on diagnosing the cause of failure in this file from cmp.

http://www.cmpcorp.com/files/techman.pdf

Jon :)

[airefresco]

The compressor has already been replaced by another company, so its not possible to check what the damage is. Basically what is going on is that the compressor went down and the guy who replaced it has blamed me for it failing as he apparently found the loose neutral. as far as I am aware the compressor wasn't stripped down or anything its just that is what the guy is saying. he also claims he found a leak on the system and a few other minor issues. I last worked on the system 6 months ago, so if it was me that didn't put the neutral in right (which i am sure it was right) then it would have been running like that for at least 6 months. The contactor has not been changed and is still the original. There are no burn marks or anything on the contactor. When it was tripping, it was tripping the main 3phase breaker, so I guess it was siezed.

[nike123]

Check voltage unbalance at compressor terminals which must be less than 2%.
http://www.cncexpo.com/UnbalancedVoltage.aspx
Does old compressor has been fitted wih Kriwan (int69) compressor overheat protection? Usually it is supplied already fitted in compressor. Is that protection been in any way bypassed.
What about overload protection of compressor? Is it fitted or not? If fitted, is it acted or not?

[install monkey]

when changing a compressor it is good practice to replace contactors/relays capacitors etc-his fault for doing an impropper job.
10yr ago i went to a trane 8 cylinder comp that was changed over the weekend-i found the contactors still had the labels ik41 ik42
original-cost ac2000 about 8k to remove and refit!

[monkey spanners]

If the compressor had been damaged by a chattering contactor caused by a loose neutral then it would show signs of burning.

Its one of the easiest things to blame the previous company for faults as the compressor changer has done, i'm sure if this had been the cause of the problem it would have shown up in the first week and not 6 months later! As for the leak, does this new chap guarantee that nothing will go wrong on ten year old equipment, sounds like a right muppet.

Jon :)

[chillin out]

I agree with the 2 monkeys above me, it is good practice to change the switchgear with a new comp, especially if the old comp has been taking out the main breakers.

if the contactor was at fault then you would notice almost straight away, the contacts would be blown apart and the new comp would not work.

The guy accusing you needs a good kick in the a$$, firstly, for blaming a fellow workmate, secondly, for not replacing the contactor and thirdly for just generally being a gimp as all loose wires are sorted with only a quite word to the suspected engineer to let him know.

Chillin:):)

[simon@parker]

have worked on alot of frascolds and to be honest they are not the best make of compressor if the replacement has exactly the same feet and fittings will be supprised as the other guys have said you dont blame the other guy for stuff failing it does some times for no reason other than a poor build compressor perhaps you should point out his poor practice when he changed the comp :) lol

[airefresco]

Thanks lads, that´s exactly what I thought. Because the other "engineer" has blamed me, the client is threatening legal action unless I pay for the compressor (700 ish euros). If I believed that it was my fault, then I genuinely would pay. However, I don´t think it was me and I was thinking exactly on the lines of what chillin was saying.

To be honest I think it is more likely that the alleged leak caused the compressor die.

I´ve seen the invoice in there is no mention of recycling costs or disposal of the old refrigerant (R22), so I wonder what happened to that? All that has been charged is the compressor, R422(or whatever refrigerant was used), oil, and 90€ labour.

[nike123]

Still, you did not telling us what protection devices are on that circuit and if they are properly functioned in time of compressor failure.
If you have installed and properly set overload relay than chartering of contactor caused by loose neutral wire would cause relay action.
Etc...

[Tayters]

Hi Paul,

Funniliy enough I came across a similar problem a few weeks ago.
Two of the fuses feeding a contactor powerering a 3 phase compressor had blown and the overload was on autoreset so... the contactor chattered like Billy O.
The electrician had already disconnected the contactor but the thing smelt like that electrical burning smell. Tested compressor with megger, replaced contactor, overload and fuses and the compressor ran.

Moral of the story: chattering contactor would probably smell burnt, may or may not have knackered the compressor depending on what safeties were employed. Also as mentioned they should have been replaced with the new compressor.

Would a chattering contactor make a compressor seize or burn out windings?
I personally think the latter.

Devious tech just trying to make himself look good. Deserves a boot up the crack of his 10 dollars!

Cheers,
Andy.

[airefresco]

Still, you did not telling us what protection devices are on that circuit and if they are properly functioned in time of compressor failure.
If you have installed and properly set overload relay than chartering of contactor caused by loose neutral wire would cause relay action.
Etc...
I don't know Nike, I've never worked on the compressor. The only thing I know for sure is that the overload on the contactor was set on TEST, but I never set that so it must have been like that before I got there, or the guy who changed the compressor set it to test to prove a point.

[chillin out]

You said you have never worked on the comp. So who faulted the comp?
How do you know that the comp had failed?
I have seen many unnecessary changed comps.


1. You need to get the comp checked by an independent person.
2. You need to check the clients setup, i.e. is the comp adequately protected should something go wrong?
3. You need to point out the other companies faults. (might seem childish, but hey thats life)
4. You need to give this guy a proper slap in the frizzer.

Chillin:):)

[NoNickName]

All this for 1HP compressor. Come on, get a life.

[airefresco]

All this for 1HP compressor. Come on, get a life.
Exactly

The old comp has been binned so it´s not possible to check the cause. The problems started after the comp was replaced and the "engineer" told the client what he thought was the definite cause of the fault. By this time all the work had been done and he had already done all the necessary repairs, in his opinion and everything was working again.

I meant I had never worked on the compressor until it failed. When I got the call I can´t remember exactly what I did to prove it was the compressor. I remember disconnecting things (fans, comp, etc) in the control panel until the breaker stayed in, from there I figured it was the compressor. I disconnected the compressor from the contactor, so I may have loosened the neutral then. After that I cant honestly remember what I did for sure. Once it had been established that the compressor was dead, I sort lost interest in the job as the client is a nightmare to work for and get paid from. He pays, but complains about it and does his best to get the bill knocked down. The last paid job I did I told him it would be about 100€ and it was 105€ and he made a right fuss about the extra 5€. So I figured I don´t really want to get involved when we are talking 1000€ or more, it just wasn´t worth the hassle. Clearly I was wrong, as if I had just done it, then none of this would of happened.

Protection wise, (from memory) there is very little. There is a local circuit breaker for the full fridge system. The contactor has an overload (which was set to TEST apparently). That´s it other than an LP switch. No 3-phase protection or anything fancy like that. I can´t remember if there is any protection on the compressor itself. I imagine there must be thermal overload or something on the actual compressor.

[B G Scott]

I think this is a little unfair, you may work for a large company and this may seem small beer to you but to some one (self employed) at the coal face this is real money.
If you are on your own you need advice and this is what was being requested.
I feel we should be helpful in this matter, it's all a matter of degree, the customer thinks 700/1000 Euro's is a lot of money, so does the the originator of this post, so don't dismiss the issue just because you feel it is an insignificant amount.

[B G Scott]

All this for 1HP compressor. Come on, get a life.

I think this is a little unfair, you may work for a large company and this may seem small beer to you but to some one (self employed) at the coal face this is real money.
If you are on your own you need advice and this is what was being requested.
I feel we should be helpful in this matter, it's all a matter of degree, the customer thinks 700/1000 Euro's is a lot of money, so does the the originator of this post, so don't dismiss the issue just because you feel it is an insignificant amount.

[monkey spanners]

If all else fails, do what the wholesalers do and just give him a credit note, for whatever you think a ten year old compressor with patchy service history is worth....

[simon@parker]

monkey spanners good idea i would give him the body deposite on a 10yr old frascold :) which last time i changed one was nothing as they dont re use old frascolds :) lol

[billy7]

just a quick reply. maybe delay timer on compressor control circuit should be in place. constant erattic comp starting and stopping can cause oload to trip but not mains . but mains being rcd can trip. i would look into control circuit protection . in my 20 odd year experience new comp do not fail in short period of time, usally another reason.