Compressor wiring questions

[Gray Mole]

I was wondering...

I have gotten ahold of a few 110v compressors, and here in the UK it's 240v. Is it possible to run 2 compressors in series and drop 120v on each and have it work or will it work that way? They use start caps so I'm just not sure if it's something that's even possible to make work with 'em.

I can just use inverters, but would be interesting to play around making dual compressor systems, or in something like a cascade using twin compressors for GPU dual evaps and the like, where 2 compressors would be used anyway. I haven't really seen anything on it before so thought I'd ask the question.

Also, I've just gotten a Sanyo approx 3/4HP(unsure of exact spec as it's not listed anywhere I can find) compressor, and there's no start cap for it, so I'll have to get one. Is there any way to approximate the cap I'll need for it? All I have on it is the model number (C-D 40L51) and that it's 240v, 50hz, single phase. I don't even have an LRA or anything to work with, just that the guy I got it from said it's a 3/4HP low temp compressor. (He's in the trade, so I have no reason to doubt that, but no way of checking as it's not on Sanyo's site) Any idea's or am I stuck waiting to get a reply from Sanyo for a spec sheet?

Was thinking it's a good High stage unit, shoudl give good capacity.

Cheers

Gray

[saratoga]

If they were identical it might work, but the frequency would be off, so you'd be running 20% under their rated RPM. I'm not sure how they would tolerate this. You'd also run into some problems with grounding I think (though I've not looked at compressor wiring in much detail so I'm not sure).

A much better idea would be to get different compressors.

[Gray Mole]

They were pretty much free, or close enough to it, so I have them around anyway. I'm in no hurry to use them, so it's not a big deal.

I thought that it might make a difference on frequency, though one of them states '110v 60hz/115v 50hz' on it, so I really don't know if it's that big a deal as long as the capacity is there, a little loss isn't going to kill me.

I don't know if perfectly matched compressors would be an issue theoretically as they'll have 120v each dropped on 'em, and draw teh amperage as they need it independently, but on start it might be an issue if the start caps are mismatched I'd think, that could spike one or the other.

Cheers for the response. :toast: Getting inverters here that can handle the amps isn't all that hard, it's just I'd thought about the series setup and thought I'd ask the question.

Don't suppose you'd know how to size start caps by any chance? :D

Gray

[saratoga]

I don't know if perfectly matched compressors would be an issue theoretically as they'll have 120v each dropped on 'em, and draw teh amperage as they need it independently, but on start it might be an issue if the start caps are mismatched I'd think, that could spike one or the other.

No, they both get the same current. Voltage drop will scale up and down to ensure this. Put a 1/4 and a 1/2 HP in series, and you'll get 60v across the 1/2HP and 180v across the 1/4 HP, with the same current through each.

Cap size would be the sum of the individual cap sizes I think. You'd have to put them in parallel for this to work. In theory it shouldn't matter, so long as the units are identical.

Edit: From the sound of it, you're not too familar with AC power. I'm not sure you should try and do this.

[_HL4E_HalfLife_]

I seriously would not do this man!!! ur just asking for trouble :nono: :nono: :nono:

Use a 220v to 115v inverter.

[Gray Mole]

I rewire cars all day long, but I don't rewire houses :rolleyes: so you're quite right, I'm not as familiar with AC as I'd like to be :p:

That's fine, I'll just strap inverter's to 'em when I use 'em. There's 2 3/8HP and one 1/4HP there, one of 'em is new. I'll have to have a look at what to do with 'em once I'm done the bigger project.

Will have to drag the bigger compressor down to the supplier's and see if they can size up a cap for me if Sanyo don't get back to me.

Gray

[Gray Mole]

Well I found a large start cap in the collection of things that I got from my new 'guy'. 400vac, 25microFerred Shizuki cap.

I stripped another prewired compressor to check the connections, and wired it up. Works like a charm :D

Now I just need to know what the 3 ports on the bottom are all about. One of them seems to be a discharge, but neither of the other 2 seemed to pull OR push, so I'll have to test that out later, unless they ever get a spec sheet back to me.

I didn't let it run more than a couple seconds, just enough to know it's working and doesn't sound like a lawn mower :p: but I'm happy enough now.

I saw gclg2000's thread on his cascade and I noticed he wired his rotary's without the coil and all that, which gave me 'inspiration' to try it out. :toast: Worst case, other than the power going out at the breaker is me looking for another compressor if I got it wrong, but it's pretty easy when you've got a wiring map.

Just a thought, the 3 ports at the bottom...is it possible this is meant to be a large recovery compressor? If it is, can I still run it as normal if I just cap them off(unless there's a breather in there or something?) I'm not really up on the recovery units.

It works anyway, and I've got a start cap that seems to work just fine with it, so one step forward I suppose :woot:

Gray

[Gray Mole]

http://www.imgbox.co.uk/uploads/8a7106e7dd.jpg (http://www.imgbox.co.uk)

Oh yeah, that's the compressor again, the top ports look normal enough, it's the 3 on the bottom left that kind of puzzle me. Top is discharge, but the lower 2 didn't seem to do much.

Gray

[Gray Mole]

On more thought on it. When I fired it up, it's seemed to want to 'spin'. I've never had a rotary, so I'm not sure what they 'feel' like when they start up, but I don't have the rubbers on it and it started turning both times I fired it. It really looks like a regular average recip to me, but without specs I'm only guessing.

It IS perfectly round, come to think of it. It's just not tall and narrow like I'm used to seeing on the copeland's and such.

Still doesn't explain the 3 extra ports though :rolleyes:

Cheers

Gray

[pythagoras]

I'm guessing here at maybe an oil return port and the other two as an oil cooling loop.

Regards

John.

[Gray Mole]

Hmm...

If I could get the capacity from the 5/8HP recip to run the high stage, that might be useful on the low.

I wish Sanyo would email back. I'd be happy to BUY a spec sheet from them if I had to :rolleyes:

Gray

[pythagoras]

You can check if two are oil cooling loops :D Blow in one and see if you get air out of the other :toast:

Regards

John.

[Gray Mole]

Very technical :doh: maybe I shoudl have thought of that :D

Yes, the 2 lower ports 'blow through' and the upper one 'pushes' so I suppose that's what they do.

So what do I do with them? Could refrigerant (gas or liquid) be subcooled there? If I didn't want to use use those ports what should I do with them? A fair bit of pressure comes out of the top port, so I don't know if I should just cap it off. I'll have to keep blowing and see if the top port on the bottom, and the discharge port on the top are directly connected. If the are connected, I could simply cap it and use the compressor as normal I would imagine and just cap all 3.

Incidentally, where in the UK are you John? Regarding our splintered PM conversation it would good to know if shipping would be a big issue.

Gray

[pythagoras]

If they are what I think they are you could cap all three. I'm in Wigan, you know the right side of the pennines, And yes I am a season ticket holder :D , what position are you in??? :D

Regards

John.

[Gray Mole]

That's not so bad, I'm in Wakefield fairly regularly so the world IS small after all :p:

I'm up near Newcastle, though I've only been here about 4-5 years. Came from Canada, so I can't have season tickets. If I cheered for the wrong team I might get killed. :slash:

That's good to know then. They're currently capped with strange/very hard to get in and out rubber caps which I thought was unusual, but once I get a chance for a proper test, I'll make sure I can just braze caps on them.

I have a 5/8HP MP14FB 'Lux Recip compressor, and side by side the Sanyo is 2" taller, 2" wider, and round instead of oval. Approx double the size and weight overall. If it is a rotary, just a short rotary, what kind of HP do you think it might actually be? I suppose the internal will decide that more than anything to do with it's size. 210mm/8 1/2" high and wide, and round.

Just seems that he'd said he thought it was about 3/4HP but seems like for it's size it coudl be higher.

I need a spec sheet :rolleyes:

Gray

[EMC2]

I'm not sure what they 'feel' like when they start up, but I don't have the rubbers on it

Blow in one and see if you get air out of the other

So what do I do with them?

what position are you in??

Ummm... what was that PM sequence about? :lol:

Sorry, couldn't resist today :p:

[pythagoras]

Okay Einstein, very funny :toast:

Regards

John.

[Gray Mole]

:wasntme: