Sealey trips out

[tigler]

Just to clarify, the trip that is causing the problem is an overload trip, not a thermal trip.
Now it's either faulty and therefore tripping prematurely or there is an overload caused by another fault in the motor or related component.
My fault finding philosophy is to eliminate the easiest and most obvious potential causes first, before getting in to more detailed examination.
The next thing I would do is bypass that overload trip and see how the motor behaves then. If it shows any sign of struggle to start, even under a cold, pressure start, then I would investigate the start and run current and the caps. But my bet is that the trip is kicking out prematurely.
Testing caps without a test rig that can test under working voltage or near to it is a waste of time. A megger may detect leakage at high voltage but it can't test the caps value. However, if either is leaking at high voltage they are on the way out anyway.

 

[brightspark]

theres not much point in using a megger on the capacitors for earth leakage .they wont be any even if there chuffed . they have plastic cases so are insulated from the earth

 

[Cret]

Sorry, I keep referring to it as a thermal trip as that's what the Sealey parts diagram refers to it as. I'm going to claim therefore it's 'their bad' and not mine.

Specifically:

The motor of the compressor is fitted with a thermal breaker located in the housing on top of the motor. The manual resetting button is located in the end of the housing as shown in fig.10A. When the breaker is tripped, wait for a few minutes and then press the reset button.

Anyway...

I will go out now and try bypassing this. I can get a new one on ebay for about a fiver so that's not an issue.

The only issue I can see with the suggested test of bypassing this and seeing if the motor struggles is that it's a fairly subjective test I suppose, in that for me, with it having been misbehaving most of the time I've owned it, it might not be quite as obvious what a hard start is compared to a normal one (ie if it's never doing a normal start I can't compare it to that). Hope that doesn't sound jibberish - I know what I mean at least!

Will try it anyway and report back.

 

[tigler]

The test I would use it for is internal leakage across the cap terminals, to indicate internal breakdown. If there were any they won't work as a cap and could cause high current draw.
However, the fact the motor starts and runs tends to rule that out.

 

[tigler]

Sorry, I keep referring to it as a thermal trip as that's what the Sealey parts diagram refers to it as. I'm going to claim therefore it's 'their bad' and not mine.

Specifically:


Anyway...

I will go out now and try bypassing this. I can get a new one on ebay for about a fiver so that's not an issue.

The only issue I can see with the suggested test of bypassing this and seeing if the motor struggles is that it's a fairly subjective test I suppose, in that for me, with it having been misbehaving most of the time I've owned it, it might not be quite as obvious what a hard start is compared to a normal one (ie if it's never doing a normal start I can't compare it to that). Hope that doesn't sound jibberish - I know what I mean at least!

Will try it anyway and report back.

I think they are confusing how the trip works with what it's function is ! It is thermally operated, but it is to protect against the motor drawing excessive current, or overload.

I know what you're getting at with how the motor behaves. Basically on this type and size of motor in this application it should start immediately, well, as far as a human can perceive anyway, even under load. If it takes even a second or two before reaching operating speed suspect a problem. Especially if there is a noticable buzzing hum as it starts.

 

[Cret]

Right, thanks for that description as the compressor behaviour seems to fit in with what you're saying there.

Removed the overload and replaced with two spade connectors and a wire.
Pulled the start button and the compressor started and ran. I could tell that it would have activated the overload though had it been fitted.

Specifically, I would say it ran slowly for between 2 and 3 seconds then suddenly got up to normal running speed and was fine then. I would suggest that with the breaker fitted as normal it is more like this:
1) If it does start, it runs slowly for 1-2 seconds then gets up to speed.
2) If it fails, it runs slowly for 1-2 seconds or so then trips the overload.

Turned it off after a few seconds then tried again.
Second time it turned over slower and after it ran slowly without picking up speed I turned it off after 5-6 seconds as I didn't want to burn anything.

Third time, it ran slower, and after a 3-4 seconds I detected it was about to/had marginally startet to hum so I rapidly turned it off. That's where I've left it.

So something is badly wrong it seems.

Based on what I've gone through so far, I do not believe that it is nor could be pressure in the system in any shape or form, causing it to hard start. Here are some problem cause eliminations in my opinion:

1) The valves all appear fine and I have swapped check valve/unloader
2) There is no residual pressure in the lines when I have undone them between unloader and pump etc.
3) The pump is very very easy to turn by hand (single finger)
4) It doesn't appear to be the overload protector since it still struggles with that removed.
5) The MCB has been increased to a B20 so I doubt it's the wiring supply to the compressor?

So is this then narrowing it down potentially to the motor itself or capacitors?
If it was the motor, I would assume there would be a physical malfunction/failure that would pretty much give the same behaviour each time it was run rather than the sporadic behaviour it is giving. Is that correct?

Capacitor wise, could it be they are both faulty, or more likely one than the other? And if they need replacing, where's a good source for quality replacements rather than the same ones that are already fitted?

Sorry for so many questions. It feels like I'm narrowing things down a bit at last which is giving me a spark of hope that I haven't wasted a huge amount of money giving my hard saved money to Sealey!!

 

[tigler]

Right, thanks for that description as the compressor behaviour seems to fit in with what you're saying there.

Removed the overload and replaced with two spade connectors and a wire.
Pulled the start button and the compressor started and ran. I could tell that it would have activated the overload though had it been fitted.

Specifically, I would say it ran slowly for between 2 and 3 seconds then suddenly got up to normal running speed and was fine then. I would suggest that with the breaker fitted as normal it is more like this:
1) If it does start, it runs slowly for 1-2 seconds then gets up to speed.
2) If it fails, it runs slowly for 1-2 seconds or so then trips the overload.

Turned it off after a few seconds then tried again.
Second time it turned over slower and after it ran slowly without picking up speed I turned it off after 5-6 seconds as I didn't want to burn anything.

Third time, it ran slower, and after a 3-4 seconds I detected it was about to/had marginally startet to hum so I rapidly turned it off. That's where I've left it.

So something is badly wrong it seems.

Based on what I've gone through so far, I do not believe that it is nor could be pressure in the system in any shape or form, causing it to hard start. Here are some problem cause eliminations in my opinion:

1) The valves all appear fine and I have swapped check valve/unloader
2) There is no residual pressure in the lines when I have undone them between unloader and pump etc.
3) The pump is very very easy to turn by hand (single finger)
4) It doesn't appear to be the overload protector since it still struggles with that removed.
5) The MCB has been increased to a B20 so I doubt it's the wiring supply to the compressor?

So is this then narrowing it down potentially to the motor itself or capacitors?
If it was the motor, I would assume there would be a physical malfunction/failure that would pretty much give the same behaviour each time it was run rather than the sporadic behaviour it is giving. Is that correct?

Capacitor wise, could it be they are both faulty, or more likely one than the other? And if they need replacing, where's a good source for quality replacements rather than the same ones that are already fitted?

Sorry for so many questions. It feels like I'm narrowing things down a bit at last which is giving me a spark of hope that I haven't wasted a huge amount of money giving my hard saved money to Sealey!!

Ok, seems we are getting somewhere now then !! That motor behaviour indicates a fault as you correctly assume. Seems the overload trip is ok. Next likely culprits are the caps. If one is faulty, most likely the start cap as that is the one that is subjected to the most current, then the other won't be far behind. Maplin stock motor caps, but I don't know if there is a branch on the IOM ? Failing that, some electrical wholesalers stock them but they will be more expensive from them. You will more than likely find that new caps will have different dimensions from the existing ones though. So if they won't fit inside the terminal box you would have to install them externally. This isn't a problem from the functional point of view, I've done it frequently.

 

[Cret]

Ok cheers. No, no Maplin over here alas. Used to be a Tandy but even that was a LONG time ago and they were very limited.

If they don't have the exact same ones does it matter? And if I get slightly different ones is it better presumably to have a bigger microfarad rating (say 200 instead of 150 for the start one if I can't get 150) rather than smaller?

Will see what they have in stock.

One interesting point I forgot to mention in my last post was that before I removed the overload breaker, I tried to short out the start capacitor (since I was touching spade terminals extremely close to those on the cap). This was just after the compressor had stalled, but I could not get either the start nor run capacitor to spark with a screwdriver across the terminals. Seemed a bit suspicious but I forgot to mention in my last essay post.

Are these things so bad that they more or less fail out of the box? And as per a previous question (I think) can they exhibit intermittent starting behaviour when they're on their way out or do they just die plain and simple?

 

[eil]

For what its worth I personally wouldn't test by by-passing the overload first, but seeing as you have already done so and eliminated that from the equation so to speak we can say thats not the problem, regarding the clamp meter even so its not a super dooper one it will be useful to ascertain the run current. Now sticking my neck out here I would think its a weak or nearly failed run cap first, start cap as a second possibility, and thirdly a poor contact on the centrifugal switch in that it makes on rest sometimes but not at other times. you will be able to test this when you receive your clamp meter and connect it up to the start cap wiring,which should show high amp draw on switch on and then drop to nearly nothing when run up to speed. Can you hear the clicking noise at the back of the motor when you start it and it comes up to speed that is when it actually starts and keeps running ?.

 

[tigler]

You need to find caps as close as possible to the exisitng value, that is quite important. Within 10 microfarad.
The fact the caps didn't cause a spark could be because there are bleed resistors across them, there certainly is on one of them.
I've frequently observed that modern caps have a considerably shorter life than older ones, this is due to many of the materials used in the construction of older caps now being illegal due to environmental issues !! Insulators used in modern motor caps are not as good as the older types so they fail more easily and quickly. The worst characteristic is that they can fail even when not in use, like as in storage. So, motor caps need now to be considered as a service replacement item IMHO.
Failure modes can be of several varieties, internal leakage, change in value, leakage under load, short circuit, transforming to low resistance at working voltage, shorting at more than a certain current, etc, etc !!
And yet I have old, as in 30-40 years old, compressors with original caps that still work
perfectly !

 

[Cret]

Thanks for the info.

I haven't noticed any sort of clicking noise at all if I'm honest and I am usually pretty good at picking up on things like that unless they're really really discrete.

Will try to listen again though.

Maplin capacitors are too small as they only go to 30uf and I need 150 for start and 45 for run, going on the labelling on the original ones.

 

[eil]

You wont get a much of a spark across the terminals if they have a bleed resistor like the one on the start cap you have, and yes quality of caps nowadays are poor to say the least.

 

[Cret]

Only one of them has a resistor (the start one), the run one does not have one. Couldn't get either to spark, but I forget the specifics of what stage I was trying this (ie whether they would have been likely to have charge anyway).

I read an article the other day saying the same thing, ie that modern capacitors are poor compared with old ones due to materials no longer permitted. It's the same with solder I believe and lead. The reason many people believe it's so common for expensive electronic items to fail so easily these days.

 

[eil]

Could you not ask your sparky mate if he has a capacitance measurement on one of his meters, they should be within 10% of their rating, you can replace with 10% higher rating but not lower.

 

[Cret]

I'll give him a shout tomorrow to ask if he's around my way imminently.
The island isn't a big place and he gets around a bit, but I'm getting more and more impatient in wanting to get this sorted now after what I've spent on buying it.

 

[tigler]

The capacitor function on a normal multimeter can only go so far in checking caps. The value may measure fine but it's leakage or behaviour at working voltage that is main factor, particularly with high voltage caps. Also, many modern induction motors don't have a changeover switch, in fact the lower power ones generally don't. They are known as permanent split capacitor motors. It's just a pity you can't do a substitution test with new caps. I'm pretty sure it is one or both of the caps causing the problem.

 

[Cret]

From the amount this has been narrowed down ( ie eliminating other items from the tests), and other peoples comments such as your own, I'd be happy to buy new ones once I find a place selling suitable ones (and assuming they're not too pricey).

Either that, or I could send them both to Sealey and ask them to test and if necessary replace them? I can't really send the whole machine back, but maybe they'd accept me just sending those.

 

[eil]

The capacitor function on a normal multimeter can only go so far in checking caps. The value may measure fine but it's leakage or behaviour at working voltage that is main factor, particularly with high voltage caps. Also, many modern induction motors don't have a changeover switch, in fact the lower power ones generally don't. They are known as permanent split capacitor motors. It's just a pity you can't do a substitution test with new caps. I'm pretty sure it is one or both of the caps causing the problem.

If his motor was a PSC motor then why does it have start and run capacitors, and if this motor doesn't have a changeover switch of some sort, centrifugal, relay or solid state how does it disconnect the start capacitor out of the circuit when its up to speed, the motor we've got here is clearly a cap start cap run type, lets not confuse the situation more.

 

[eil]

From the amount this has been narrowed down ( ie eliminating other items from the tests), and other peoples comments such as your own, I'd be happy to buy new ones once I find a place selling suitable ones (and assuming they're not too pricey).

Either that, or I could send them both to Sealey and ask them to test and if necessary replace them? I can't really send the whole machine back, but maybe they'd accept me just sending those.

Cant hurt to contact them, I'm sure they have had this problem before but wont admit it.

 

[Cret]

Well I may have found some suitable caps but I'm not entirely certain. Looks like it'd cost me £30-40 posted to get both of them, assuming these will suffice.

http://uk.rs-online.com/web/p/produ...07566206D6F746F722673633D592677633D4E4F4E4526

http://uk.rs-online.com/web/p/produ...072756E20343575662673633D592677633D4E4F4E4526



Shame as it would be nice not to spend this much, especially since it won't come with a guarantee of curing the issue....