Fused panel and breaker?

[Dr.HairyOlds]

So i just picked up a Quincy QE-10 compressor. It's 240V 3 phase 10 hp motor that draws 28 amps according to the tag. I had planned on buying a 30 amp, 3 pole breaker for it but it came with the fuse panel it was wired with.

My questions is: Do I need a breaker or do I wire the fuse panel direct?

What would a direct connection in a box look like? If anyone can identify the different legs that would be great.

Another question: Assuming I use the fuse panel, it has 100A RK5 time delay fuses in it. That is how the last guy was running it. Is this correct? Should/can I swap the fuses out for a lower amperage to better protect the compressor?

 

[Jim Johnstone]

Well I'm not an expert in electrical, but in a former life I worked in factory maintenance and dealt with a lot of 3 phase stuff. If it were me, I would be breakering/fusing it at 60 amps to deal with the startup load, and using #6 copper wire.

What do you mean when you say it came with a fuse panel? Are you referring to a fused disconnect? Also, do you have a 3 phase breaker panel in place already?

As far as identifying the different legs of the 3 phase, there is no way to do it. Hook up any 3 to any 3, remove the belt from the compressor pump, and turn it on. If it is spinning the right direction, you're set. If it is spinning backwards, switch any 2 of the 3 connections, and then you're set.

One last thing to mention. The fuses/breakers aren't there to protect the compressor motor, they are there to protect the wires from overheating. That's why you ALWAYS size your wires and breakers/fuses to match each other.

Jim

 

[trainer]

You do have 3 phase power?
Unless you are in a commercial shop, you probably don't

With a compressor, i think it generally doesnt matter what direction the motor turns.

I've switched two legs on a locked up three phase refrigeration compressor before to get it running until a replacement could arrive.

 

[Aceman]

You need a minimum of #10 THHN. The breaker or fuses you use need to be somewhere between 35-70 amps.

 

[nehog]

...
With a compressor, i think it generally doesnt matter what direction the motor turns.
...

I think it does:

1. If there is a fan built into the pulley on the compressor (many do) the fan needs to blow on the compressor, not away from it.

2. If the compressor is 'dip' or 'splash' lubricated, there may be lubrication scoops that if going backwards won't scoop and throw oil up on the cylinder walls and wrist pins.

Many compressors have a cast in mark indicating direction of rotation.

 

[Charles (in GA)]

So i just picked up a Quincy QE-10 compressor. It's 240V 3 phase 10 hp motor that draws 28 amps according to the tag. I had planned on buying a 30 amp, 3 pole breaker for it but it came with the fuse panel it was wired with.

My questions is: Do I need a breaker or do I wire the fuse panel direct?

What would a direct connection in a box look like? If anyone can identify the different legs that would be great.

Another question: Assuming I use the fuse panel, it has 100A RK5 time delay fuses in it. That is how the last guy was running it. Is this correct? Should/can I swap the fuses out for a lower amperage to better protect the compressor?

Its appears you are not real knowledgeable about electricity....... which makes me wonder......... do you have 3 phase to operate the compressor? Unless you have a phase converter large enough (rotary or otherwise....) or you actually have 3 phase supplied to you (many farms do, many commercial areas do, few residential areas do) then you cannot run the compressor and will need a new single phase motor. 10 hp is the peak of single phase.

Assuming you do have three phase, even if you kept the fuse panel, you still need to connect the wiring to the fuse panel, to the building's power somehow, and would need a three pole breaker anyhow. Some panels have the capability to tap off the bottom of the bus bars with lugs to supply another panel, but you have to use wire rated for the amperage of the main breaker that is protecting it. If it is a long run from the panel to the compressor you will need the three pole breaker to protect the wire running from the panel to the compressor's fuse panel, and probably need fuse panel at the compressor to protect the compressor (and if it has a switch, will provide the required disconnect "within 50 ft line of sight" from the compressor.

Charles

 

[Dr.HairyOlds]

Thanks everyone for you input. Let me clarify things since I wrote my last post at 1:30 am:

Here is the link to the compressor model that it is.

http://www.northerntool.com/shop/tools/product_200351026_200351026


The plate on the compressor motor confirms that it is 3 phase and says 28 amps.


The compressor’s last owner had it wired into a separate fused disconnect with 100 amp RK5 time delay fuses.


The service at my breaker box is 200A, 240V 3 phase. It is an old wadsworth breaker box. So I need to ebay breakers. This makes them expensive. A 3 phase breaker will cost me about $150. This was my reasoning on using the fused disconnect for protection since it was there already. I believe I do have bus bars to connect directly off of the main breaker. However, looking into it, replacement fuses to fit this disconnect only go as small as 70 amps.


My current plan is to pay the shot for a 3 phase breaker, wire it into the fused disconnect and use it simply as a disconnect, with the 100A fuses in place, pretty much acting as a direct connection and let the smaller breaker be the protection.

I can find 30A breakers and 50A breakers, nothing in between. So I suppose I need a 50A breaker. What size wire do I need to run? Is it pulling 30A from each connection or is it split between the three legs?


I will try to take some pictures when I get a chance to show you all what I’m working with.

 

[930dreamer]

I'd like to see some pics. If the motor tags lists "full load amp (FLA)" as 30 amps, size the wire for 30 amps. Start up amps will be much higher but only for a fraction of a second. I think you can find some good deals on cheap three phase disconnects/circuit breaker.

 

[trainer]

I think it does:

1. If there is a fan built into the pulley on the compressor (many do) the fan needs to blow on the compressor, not away from it.

2. If the compressor is 'dip' or 'splash' lubricated, there may be lubrication scoops that if going backwards won't scoop and throw oil up on the cylinder walls and wrist pins.

Many compressors have a cast in mark indicating direction of rotation.

I stand corrected!

 

[Jim Johnstone]

I stand corrected!

Yeah, I have a 5000 psi compressor that if you spin backwards, it will pretty much detonate.

 

[Thruxton]

Contact Quincy, get their recommendation on breakers/fuses. Their Web site has contact info. Use their recommendation.

 

[Charles (in GA)]

Sorry about questioning the three phase, but few people have a shop or garage with three phase, and many unknowing people acquire three phase devices thinking the conversion to single phase is cheap and easy, or not needed. After awhile one tends to question anything that is out of the ordinary.

Charles

 

[Norcal]

W/ motors the traditional rules do not apply, if the motor has overload protection, one gets to size the wire to the minimum (10 AWG ) & provide a fuse or circuit breaker to the maximum, in this case the fuses/ circuit breaker is there to provide short circuit protection & a magnetic starter provides overload protection.

 

[sberry]

I agree and if I could do it without buying an obsolete additional breaker I would. I might be tempted to use 8 wire if I was going to fuse it at 70 if I had to buy wire anyway.

 

[Dr.HairyOlds]

Sorry, no pics. But I called Quincy and here's what they recommended:

minimum 10 gage wire

40A time delay fuses or 50+A breaker.


So bought a 60A breaker. It should be here by Friday and I'll wire it up sometime this weekend. I'll try to get some pics up here and of the install.

Thanks for all the help guys.