Sealey compressor blowing RCD fuse

[droopsnoot]

I've got a Sealey SA22503 3hp 50l compressor which has been working fine. It doesn't get a lot of use, though I have been using it more over the last few months for grinding down welds and so on.

I've noticed recently that when I first try to start it, it turns over for a couple of seconds, doesn't spring into life, then blows the fuse in the RCD I've got on the end of the extension lead it runs from. On most occasions, if I get a fan heater and run it aimed at the motor for a few minutes, it will start, and once started it will cut back in again when the tank is depleted. Almost as if it's too cold, causing the oil to get thicker, and the heater is thinning it out.

Yesterday, though, I used it for half an hour or so, left it while I did something else, then started up and it blew the fuse. I replaced the fuse but it didn't seem to want to start again. I hadn't got any more spare fuses so I didn't try too much.

It's had a new capacitor last year (or perhaps the year before) but I don't think the symptoms were the same as this, and I can't think why heating it would help. It doesn't trip the RCD or blow the fuse on the compressor plug, only the fuse in the RCD. Extension cable is around 60', and also runs my radio and a flourscent tube.

On the same compressor, assuming I can get it sorted, I've noticed it's a little short of capacity and spends a lot of time refilling. Is it better for the compressor for me to pause until it's filled the tank and then carry on, or should I just carry on? I know the "proper" answer to that is to get a compressor that has the capacity, but I can't justify the cost for the work I've got left on this project.

 

[brightspark]

try running it without the extension lead it may be 2 long and your getting voltage drop and with it being cold takes more amperage to start

 

[ford34/2]

On most occasions, if I get a fan heater and run it aimed at the motor for a few minutes, it will start, and once started it will cut back in again when the tank is depleted. Almost as if it's too cold, causing the oil to get thicker, and the heater is thinning it out.

answered your own question realy, hopefully you rember to turn off the heater prior to starting the compressor. Am no sparky, but you need a Good thick extension lead, and this time of year oil will be heavy as its so cold. 3Hp pulls a hell pf a lot of amps for a split second or so starting up. 3Hp is on the electric limit. Mine is an Old Ingersol Rand 14cuft, with a 3 Hp motor, 1425RPM, not boasting but never have bother. Dedicated supply with Armour from the house to the garage,probably 50feet or so. And separtate DB in garage and all circuits protected with MCB or Dual-RCB/MCB

Stan

 

[MattH]

Possibly a bearing or bushing in the drive is on it's way out and is binding.
This would cause high starting amps and cause the machine to run poorly.

 

[the snooper]

Possibly a bearing or bushing in the drive is on it's way out and is binding.
This would cause high starting amps and cause the machine to run poorly.

we have had this topic come up many times and its always winter time and always due to temperature and thickening of the oil a little heat and they start fine

 

[Wallace]

Perhaps changing the oil for a lighter grade would help.

 

[normspanners]

Perhaps changing the oil for a lighter grade would help.

I normally end up doing this at this time of year and the one comp is in the house, ok not warm but certainly not outside temps. And I can get problems with it's OL when we get a VERY cold night.
My lead is plugged direct into a sub CU.

 

[droopsnoot]

Thanks for that. I'll have a go with it plugged directly in to the mains socket, it's just unfortunate that the layout of the shed is that the mains is at one end and the car I'm working on is at the other, and it's a long thin layout so would be really inconvenient to have it blocking the other stuff in. I did remember to turn off the heater prior to trying the compressor, I keep in mind the voltage drop as I'm sure it affects the welder too. I can deal with the compressor thing by getting a long air hose instead, but not much I can do with the welder.

 

[normspanners]

I have a 15A OL on my comp in the motor terminal box and that usually pops out so as BS said with your long extension especially if it is a 1/ 1.5mm ext cable, your initial volt drop will be significant.
The other issue maybe the pipe from the head to the check valve I have replaced mine with a long length of 12mm copper it lets the pump turn over a few times before building a high pressure.
If you are in the situation again --- where:-

Yesterday, though, I used it for half an hour or so, left it while I did something else, then started up and it blew the fuse. I replaced the fuse but it didn't seem to want to start again.

you would be better to drain ALL the air out and starting with no pressure in the tank to let the pump start with no air pressure to work against.
The other thing is your capacitor maybe showing signs of age.

 

[droopsnoot]

OK, noted. I did replace the capacitor, but as I think of it I had some suspicions that the one I bought was not brand new - as it cured the problem at the time I thought no more of it.

 

[droopsnoot]

Perhaps changing the oil for a lighter grade would help.

I'm not actually sure what grade is in it. I bought it new and it came with a bottle of "compressor oil" but I think that's about all it says. It's had quite a quiet life really, but I've been using it more recently to clean up welds as the areas I'm working on don't lend themselves to being cleaned up with electric tools - access is limited.

 

[Wallace]

Usually single weight mineral oil, harks back to the days before Mutley Grade oils in cars and bikes where you had different grades for winter & summer or extreme climates.

 

[AndyStobbs]

Must be painfully slow grinding welds back with an air grinder on that size of compressor?

 

[the snooper]

Must be painfully slow grinding welds back with an air grinder on that size of compressor?

I have an air grinder that will run quite well on that size machine although I don't use it, whats the point it costs a lot more to run the compressor then it does a normal grinder

 

[droopsnoot]

Must be painfully slow grinding welds back with an air grinder on that size of compressor?

It has been sometimes, but I'm not used to anything better and as it's my own project, I'm not against the clock. The electric grinder is sometimes too big to get in to corners or next to right-angle flanges and so on, so the die grinder or 3" cut-off gets used instead. It's not as long-winded as grinding them back with my Aldi dremel-a-like, in any case.

 

[droopsnoot]

I tried the compressor this afternoon directly into the mains socket, and it started perfectly fine. OK, it's a little warmer than it was when I was having trouble, but not much, so I'll either go for a better extension cable (reading another thread suggests that might get quite expensive, though it might also help the welder) or get a long air hose. Thanks for the advice in any case. I did run the heater on the oil for a couple of minutes first.

By a quirk of fate, the mains socket is quite high up on the wall, around 6" out of reach of the standard mains cable. So if I go with the longer air hose, I'll have to find some pallets to raise the thing off the ground.

 

[the snooper]

I'll either go for a better extension cable (reading another thread suggests that might get quite expensive.

how long do you need the extension cable to be ?

 

[droopsnoot]

I think it's roughly 60' but I'd have to measure it. Right now it's just a basic extension cable with a 6-socket adapter on the end, but I don't know what diameter the cable is. Noticed they sell thicker stuff in Wilkos as well as on-line.