air compressor/magnetic starter wiring

[diy570]

hi, wondering if somebody could give me a pointer on hooking up my new compressor. the mag starter on this one looks different from my old one, and i just want to be sure i hook it up properly. the starter is already run to the switch, so i just need to hook up the black and white wire from my breaker box. does the black wire go to the upper left (L1), and the white go to the upper middle (L2)? the starter is a single phase.

thanks in advance and here are two photos to show the set up.

 

[71flh]

It looks like a 3 phase starter wired to run a single phase load to me but I'm no expert. I'm just giving you a bump...

I take it your feeding it 240V single phase?

What size cable and breaker?
What are the requirements of the compressor?

I'd say L1 and L2 is right, but don't trust me. With 240V it makes no difference which wire you connect to L1/L2.

I'm curious about the small red and black wires, where they go, and what they're connected to internally and externally. No doubt one set is to the pressure switch.

 

[diy570]

thanks. yea, its 240 single phase. i'm using 10 gauge and a double 30 amp breaker for my other compressor at the moment. this one calls for 35/36 amps i believe. the extra smaller wires go to the low oil shut off switch.

 

[71flh]

What compressor is it?

Mine's the 735 in the pic in the link, but not new and shiny... I bought it used about a year ago and had fun running wire and air lines for it.
http://www.saylor-beall.com/air_compressors/tank_mounted_vertical.php

 

[diy570]

this is the one i bought, hopefully the last one i'll ever need. i'm pretty excited to get it hooked up and running.

 

[PsRumors]

Nice looking compressor. What are the specs?

 

[930dreamer]

Did you get the compressor wired, and the Bus?

 

[diy570]

Nice looking compressor. What are the specs?

thanks, its a 7.5hp, 80 gallon.

Did you get the compressor wired, and the Bus?

i didn't get it hooked up yet, i still have to make room for it and getting it moved into my tool/compressor room is gonna be a task in itself. as for the bus, i'm finished doing my part to it and it will be getting picked up this coming week.

 

[71flh]

Now that's garage art!

I guess you'll be pulling a new feed for it? I'd guess the 30A circuit isn't going to cut it.

 

[diy570]

can anyone tell me why power would be going into the magnetic starter, but not coming out where it feeds the motor? i have power at my pressure switch as well. this thing has a low oil shut down switch too, can these be faulty?

 

[71flh]

What do you mean by not coming out?

How did you connect power?
Does the starter engage?
Do you measure 240V across L1-L2?
What do you measure across 96-98?

 

[Zrexxer]

And what kinds of overloads/heaters do you have, and are they installed correctly and engaged? That's almost identical to my Champion, except mine's a 5 hp.

 

[dwm]

http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/td03309004e.pdf

http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/td03309001e.pdf

 

[diy570]

What do you mean by not coming out?

How did you connect power?
Does the starter engage?
Do you measure 240V across L1-L2?
What do you measure across 96-98?

by not coming out, i guess i mean that power is going into L1 and L2, but not coming out down at t1 and t3 to feed the motor. im going to try and find an electrician tomorrow who knows about compressors. i'm getting frustrated and don't know much about electrical other than very basic house wiring.

L1 reads 123 and L2 reads 123 volts.

 

[71flh]

You want to put one meter lead on L1 and the other on L2 to make sure you're getting 240V.

What about the measurement at the motor side? T1-T2 and/or 96-98

 

[diy570]

i tried to get a reading across the two, but it still only read 123. t1 and t2 show nothing at all. 96 shows 123 because its run through the low oil switch which gets power from L2.

 

[930dreamer]

Sounds like the coil isn't closing the mag switch.

 

[930dreamer]

by not coming out, i guess i mean that power is going into L1 and L2, but not coming out down at t1 and t3 to feed the motor. im going to try and find an electrician tomorrow who knows about compressors. i'm getting frustrated and don't know much about electrical other than very basic house wiring.

L1 reads 123 and L2 reads 123 volts.

You have a wire going into L1 & L2, then you mention T1 & T3? Have you tried T1 & T2?

 

[diy570]

do you think it could be a bad coil? t2 has a wire that connects back to L3 at the top. looks weird to me, but thats what the diagram shows as well.

 

[930dreamer]

Seems to me L1 & L2 should/must go to T1 & T2 not sure of the jumper going to T3?. I've manually closed a three phase mag switch with a piece of wood while trouble shooting.

 

[71flh]

I'm also wondering why the jumper is there, but I doubt that its a problem. It just seems to route current through the 3rd set of contacts and heater.

Thus T2 and T3 are pretty much the same point electrically if the contacts are closed.

Maybe he's only got one leg of his 240V power feed.
Flip the breaker off and back on?

The drawing in the first pdf from the post by dwm is informative.

It looks like the red wires are from the low oil SW.

The small black wires are from the pressure SW. Its hard to tell where all the black wires are connected. The coil connections can be seen behind L1 and L2 in the background of the 2nd pic.

 

[diy570]

thanks for all the advice, guys. my compressor guy/electrician showed up today and it turns out that i have a bad meter base for my shop. i was getting 120 from each leg, but not 240 when you check between both. the electric company came out and pulled the meter and the one lug for the wire incoming was rusted/burnt nearly off! the strange thing is that my last compressor was a 220v, but the motor was only a 5hp. not sure how it limped along like that. i ran it up until yesterday. ***** to spend more money, but probably good that i caught it now before burning up this unit.

anyway, enough rambling. thanks again for the help, i really appreciate it.

 

[930dreamer]

Is it running yet? How about now?

 

[Milton Shaw]

Looks like its wired completely wrong. The line1 line2 should be the hots, the ti t2 should be the load (motor) nothing should be hooked to l3 or t3. The small wires to oil switch etc, should be in series with the pressure switch which should be hooked to the coils. The heater and magnetic part should work when low oil and pressure switch close and power is applied to the coil. The heater should trip if the amp pull on the motor is enough to overload the motor. The magnetic part should trip if power is lost to the unit. The small spade terminals on l1 or l2 should be where the power for the pressure switch/low oil is powered and then goes to the coil. If the coil is 120 then that is all the circuit. and the other coil terminal goes to neutral. if the coil is 220 then wire from l2 should go to the other side of the coil. You could have the either coil wire going through both or you could use l1 little wire to low oil and l2 small wire to pressure switch(only if coil was 240volt) But hooking them in series would be the easiest to run. Only one circuit to trouble shoot, no put in then open pressure switch or low oil is tripped.

 

[diy570]

the original pictures are from when it was factory wired. the guy who came to help me out wired it differently. he said the original configuration is how they wire single phase for overload protection or something. its not running yet, gotta find somebody to install a new meter base for me so i can get back to work.

 

[71flh]

I'd guess the factory knows how to wire it better than some guy.

It might be interesting to see how its wired now...

 

[diy570]

I'd guess the factory knows how to wire it better than some guy.

It might be interesting to see how its wired now...

yeah, thats what i thought too. he wired it the traditional way to help me get it running, and then we realized that my electrical service had a big problem.

my shop is an old amoco gas/service station and its been through quite a few hands that never maintained the place properly. i'll have one more problem out of the way now.

 

[930dreamer]

Hope you get it all sorted out safely, can you post some pics of the old Amaco station?

 

[diy570]

well, i finally got my new compressor up and running. aside from the meter base being bad, the previous hacks had also only run 100amp cable from the pole instead of 200amp like my shop is supposed to have. i had them run 200amp this time.

can you post some pics of the old Amaco station?

here's one i just snapped this morning, the shop was built in 1959:

 

[wben88]

hey guys I have a similar problem as well and cant figure out whats going on with it

 

[redmondjp]

hey guys I have a similar problem as well and cant figure out whats going on with it

Welcome to the forum! Rather than resurrect a dead thread, you will be better off starting a new one. Include in your initial post as much relevant background information as you can, and pictures are also very useful.

Based upon what you have posted, we have no idea how to help you.