New Chamion 7.5 HP air compressor wiring question

[freshintulsa]

Hello all. I recently got my new compressor and am a little confused on hooking up my input power. This is 230volts SINGLE phase. My confusion is in the contactor/starter. It has 3 legs and I thought at first that they sent me the wrong one. I looked it up and it is good for single and 3 phase. It is an Eaton C25DNF340 contactor.

The two hot legs from the motor are coming into the bottom of the contactor/starter assembly. They are in the T1 and T3 terminals. Pictures to follow at the end.

The T2 terminal jumps up to the L3 terminal. I believe my two hot legs should tie into the L1 and L2 terminals and obviously my ground will go to the grounding lug in the box.

I'm no electrical expert, but have wired up my share of machines in the past, but I just thought I would ask the collective group here, who many of are geniuses!

Also, I was going to use an inline disconnect to turn off power to the compressor, but a buddy of mine at work said he used a simple switch that he wired in his box on the compressor. Has anyone done this? Any suggestions on a switch to use that can handle 60 amps?


Thanks again!
Doug

 

[pattenp]

L1 & L2 should be the 2 hots coming in. A cheap solution for a disconnect is a 60A non-fused AC disconnect, it's also rated to 10HP.

http://www.homedepot.com/p/Square-D...de-Overcurrent-Protection-QO200TRCP/202353314

 

[Charles (in GA)]

Normally three phase/single phase starters don't use the center contacts on single phase. The motor was factory connected to T1 and T3? You hook the incoming to L1 and L3, otherwise the current ain't going to get to the motor, plain and simple.

 

[freshintulsa]

I understand that logically, if the motor inputs are from T1 and T3 then the power inputs should be to L1 and L3. What is confusing me is that T2 has a wire going to L3. I guess my input power to L3 will just give 110volts to T2. Does this make sense?

Just to reiterate... the motor's power wires are going to T1 and T3. T2 has a wire going up to the top at L3.

So if my input power goes to L1 and L3, I assume that the small wires going to L2 for the low oil shut off switch will get power through T2 that is getting power from L3?

I just want to be safe and not damage anything, but I haven't gotten any answer yet from champion, and the wiring diagrams don't show anything about input power at all.

pattenp, thanks for the link to the disconnect. Does anyone know of any small switches, like on off, or a toggle, or something along those lines that will work for this setup? I'd like to put something small on the existing box on the compressor.




thanks again!
Doug

Here is an overall picture of the box on the compressor.

 

[wyliesdiesels]

....The two hot legs from the motor are coming into the bottom of the contactor/starter assembly. They are in the T1 and T3 terminals. Pictures to follow at the end.

The T2 terminal jumps up to the L3 terminal. I believe my two hot legs should tie into the L1 and L2 terminals and obviously my ground will go to the grounding lug in the box.....

Also, I was going to use an inline disconnect to turn off power to the compressor, but a buddy of mine at work said he used a simple switch that he wired in his box on the compressor. Has anyone done this? Any suggestions on a switch to use that can handle 60 amps?

Thanks again!
Doug

First of all the pics are too small. Can u repost them bigger?

Does the jumper from T2 go through the overload relay on its way to L3? If so then everything is fine. U can use a 3phase starter with single phase input with modification(already done in your case) BTW...

I dont see a pic of your overload. Im guessing u have a solid state overload relay with phase loss detection. If this is the case and Without that jumper going from T2, through the overload relay and onto L3, your starter would trip almost instantly because it wont detect any current on T2.

You want to connect your incoming feed to L1 and L2 for the above reasons...

As far as a disconnect switch, u can either get an inline disconnect as pattenp suggested or wire in a single pole light switch into the starter contacts on the overload side(not the pressure switch side)....

Normally three phase/single phase starters don't use the center contacts on single phase. The motor was factory connected to T1 and T3? You hook the incoming to L1 and L3, otherwise the current ain't going to get to the motor, plain and simple.

Nope, he said theres a jumper from T2 to L3 which leads me to believe he has an overload relay with phase loss detection...if he hooks up as u suggested, the overload relay will trip...

I understand that logically, if the motor inputs are from T1 and T3 then the power inputs should be to L1 and L3. What is confusing me is that T2 has a wire going to L3. I guess my input power to L3 will just give 110volts to T2. Does this make sense?

Just to reiterate... the motor's power wires are going to T1 and T3. T2 has a wire going up to the top at L3.

So if my input power goes to L1 and L3, I assume that the small wires going to L2 for the low oil shut off switch will get power through T2 that is getting power from L3?

I just want to be safe and not damage anything, but I haven't gotten any answer yet from champion, and the wiring diagrams don't show anything about input power at all.

pattenp, thanks for the link to the disconnect. Does anyone know of any small switches, like on off, or a toggle, or something along those lines that will work for this setup? I'd like to put something small on the existing box on the compressor.

thanks again!
Doug

Here is an overall picture of the box on the compressor.

Nope, that jumper is there for a reason. read my comment above!

As far as the toggle switch goes, u could even put it by the door...

BTW what size wire will u be using? U need #8 CU THHN or #6 NM-b....breaker can be max 100a....u need a disconnect if breaker panel is not within sight of compressor and more than 50' away...

 

[freshintulsa]

Thanks for the reply Wyliesdiesels. I am going to use 60 amp breaker and #6 THHN in conduit. All of my shop is surface mounted conduit and boxes/outlets/receps.

I'm assuming the bottom piece that connects to the contactor is the thermal overload you are talking about. here are some more pictures, hopefully they are bigger, if not I don't know how else to make them larger?

 

[freshintulsa]

One more picture.

 

[freshintulsa]

It looks like this same question was asked early, just found a link to it here on garagejournal. It doesn't seem like he really got an answer, but it seems like he used L1 and L2 to me.

http://www.garagejournal.com/forum/showthread.php?t=108444

 

[wyliesdiesels]

Thanks for the reply Wyliesdiesels. I am going to use 60 amp breaker and #6 THHN in conduit. All of my shop is surface mounted conduit and boxes/outlets/receps.

I'm assuming the bottom piece that connects to the contactor is the thermal overload you are talking about. here are some more pictures, hopefully they are bigger, if not I don't know how else to make them larger?

Yes thats the overload, though its solid state and has bi-metalic mechanisms instead of heaters...Im not familiar with that model but it does look like it has adjustable settings....

Whats the model number of the overload relay block? I will have to look it up...

It looks like this same question was asked early, just found a link to it here on garagejournal. It doesn't seem like he really got an answer, but it seems like he used L1 and L2 to me.

http://www.garagejournal.com/forum/showthread.php?t=108444

Uggg dont get me started on old threads...I love correcting them...that one was before my time on here and none of the other current electricians commented on it either...

 

[freshintulsa]

Thanks again wyliesdiesels. The overload/relay part number is: XTOB040DC1.

Looking forward to your advice!

 

[wyliesdiesels]

Yup! It has phase loss protection so thats the reason for the T2 to L3 jumper. Without that jumper and thus current flowing through the overload relay at T2, it will trip and open the contactor almost immediately! Phase loss protection is used for 3 phase motors so they dont burn up in case the motor losses an incoming phase...

Thats a pretty good overload relay. It has aux contacts that u can use to send a signal to an external device upon tripping of the relay...

The range is 24-40a so u will have to set it close to max with a 7.5HP motor, though id be surprised if it wasnt already set at the factory!

http://www.imc-direct.com/mobile/pr...w.imc-direct.com:80/product_p/xtob040dc1.htm=

 

[freshintulsa]

Wow, thanks for such quick and thorough responses. Just to make sure, I'm going to hook my incoming power to the L1 and L2 terminals on the contactor.



Thanks again wyliesdiesels!

Doug

 

[wyliesdiesels]

Wow, thanks for such quick and thorough responses. Just to make sure, I'm going to hook my incoming power to the L1 and L2 terminals on the contactor.



Thanks again wyliesdiesels!

Doug

No problem.

Yup thats correct. And motor is connected to T1 and T3 with jumper from T2 going through overload to L3....the manu probably uses these instead of buying different starters for single phase and 3 phase compressors, Im sure to save on costs....

 

[doojus]

I just wired up the the 5HP version of this same compressor, you're gonna love that thing.

 

[Charles (in GA)]

Im guessing u have a solid state overload relay with phase loss detection. If this is the case and Without that jumper going from T2, through the overload relay and onto L3, your starter would trip almost instantly because it wont detect any current on T2.

You want to connect your incoming feed to L1 and L2 for the above reasons...

Thanks for the clarification, I am not familiar with newer motor starters with phase loss detection, but it sounds like a good idea for three phase motors. I will attempt to file that one in the ole memory bank for future reference.

Charles

 

[wyliesdiesels]

Thanks for the clarification, I am not familiar with newer motor starters with phase loss detection, but it sounds like a good idea for three phase motors. I will attempt to file that one in the ole memory bank for future reference.

Charles

Yes its a great idea. Ive had to replace lots of 3-phase motors using older starters that otherwise wouldve been fine had they not been 'single phased!'

 

[freshintulsa]

Thanks again for the help everyone! I will report back with pictures when I get it hooked up. I should have time by this weekend.

 

[BFalfa]

just got my 7.5hp champion hooked up last weekend..used a knife switch as a disconnect on the wall. and for what its worth I used 6gauge wire and hooked it to the l1 and l2 terminals. works just fine.

 

[freshintulsa]

Sorry for the long delay. I had this up and running last weekend, but the drain line had a leak... ended up having a broken elbow. I'm assuming it was from during shipping, but who knows.

L1 and L2 are definitely the right connections. Works great, pumps up quick, and sounds great! I haven't had too much chance to use this compressor yet, but for what its worth, I highly recommend it so far.

 

[wyliesdiesels]

Sweet.

 

[shamrock12]

Beside with mine being 5HP, I have the exact same compressor as yours. It had to wired the same way as you did. I did notice the jumper wire from T2 to L3 and wondered the same thing. Had no idea our Eaton starters have phase loss protection which made sense.

BTW, an excellent decision to go with the aftercooler package. That will make a huge difference!

 

[roll_the_dice]

Thanks for those that came before me. I just got the same compressor delivered today and was curious why I had a 3 phase contactor...thought they had sent the wrong one also. Saved me tons of research and worry! Thanks to all the electricians that help us with our projects!

 

[bowtieboy77]

I have just finished a 5hp compressor install requiring a magnetic starter. I purchased a 1 phase mag switch but you can use a 3 phase mag switch to power a 1 phase motor. It simply requires adding a jumper wire to "trick" the overload into thinking there is 3 power legs I am no expert I simply did a lot of research before buying the mag starter. If you google or youtube wiring 3 phase magnetic starter to 1 phase motor you should find some results.

 

[bowtieboy77]

As for the on and off switch the 1phase mag switch I purchased came with the switch already wired. The switch does not need to be a high amp capable switch as you are only turning on/off the low amp coil with the switch. The coil energizes and physically closes the high amp contacts which powers the motor. The switch pulls power from L1 or L3 and goes to the a2 which is coil supply. On mine the wires also go through a thermal switch aswell. (blue wires in pic) My switch uses 3 wires the red is simply to light the switch the blue wires are the switch control. Here are the instructions that came with my 1 phase mag switch.