Air compressor contactor/wiring problem. Need help please!

[dalmatiangirl61]

Vid does not help my brain as I don't know which is the manufactured leg, I have to draw things out.

F16 has a really good point about how you are getting 120v without a neutral. Why not try 220v to the coil with the power co legs.

 

[Ltk]

What are the coil jumpers set to voltage wise, I cannot tell from the pictures. The wiring is blocking the jumper setting. I have issues watching videos due to a slow internet connection out in the sticks. Take a few pictures further back. Also I hope whatever crumbs are in that box aren't nesting material for mice or rats, they like eating wires.

I’m not sure, I hooked it the way I thought it should be but I have never wired up a motor starter before

Here are some extra pictures showing the wires and where they are leading.

The compressor once I can get it running will get a thorough cleaning out, I rescued this from a barn for free so it was/is very very dirty. I wanted to verify operation before I get it a permanent place in my shop

 

[Ltk]

Vid does not help my brain as I don't know which is the manufactured leg, I have to draw things out.

F16 has a really good point about how you are getting 120v without a neutral. Why not try 220v to the coil with the power co legs.

Sorry, the white wire (L2) is the manufactured leg from the phase converter

I'm not sure that I'm even wired to the coil correctly as I'm now getting no voltage whatsoever to it

 

[CITIZEN F16]

That looks like it is a 240/480 volt coil set for 240 I think we are getting somewhere. It looks like it needs 240 volts and I think you previously said you had 165 volts. I have never seen a contactor coil that was 240/480, damn, I am in my 60's and I just learned something new.

 

[CITIZEN F16]

Since you are running the coil from 240, you can get away with no ground or neutral as far as functionality. Let us start over. First you need to get a ground for testing voltages to ground, can you do that? That will able you to isolate the manufactured or wild leg. That coil needs 220 volts single phase to work probably +/- 20% it is just a coil, nothing but wound wire, that can be accomplished using any two legs of the 3 phase as long as they hit that number. As mentioned before it is best to keep that generated or wild leg out of the control circuit. Once we get the compressor to fire and run we will have to move wires around if it is running in the wrong direction.

 

[Ltk]

That looks like it is a 240/480 volt coil set for 240 I think we are getting somewhere. It looks like it needs 240 volts and I think you previously said you had 165 volts. I have never seen a contactor coil that was 240/480, damn, I am in my 60's and I just learned something new.

I was getting 165 but then moved the lead from the manufactured leg (L2) to L3

So where should the wires lead from the coil to? One leads down to the overloads, one leads to the terminal marked with a 3 on the left side of the unit

 

[dalmatiangirl61]

I'm not sure that I'm even wired to the coil correctly as I'm now getting no voltage whatsoever to it

There is power to all 3 main incoming wires, but no power reading at coil terminals? Is this correct?

Is there pressure in the tank? If above statement is correct, trace wires from main terminals to coil and figure out where power is lost.

Yes, your coil needs 240v.

 

[Ltk]

There is power to all 3 main incoming wires, but no power reading at coil terminals? Is this correct?

Is there pressure in the tank? If above statement is correct, trace wires from main terminals to coil and figure out where power is lost.

Yes, your coil needs 240v.

Yes that is correct and no pressure in tank, I have the belts off of the pump also as I’m currently resealing the pump

 

[Ltk]

Since you are running the coil from 240, you can get away with no ground or neutral as far as functionality. Let us start over. First you need to get a ground for testing voltages to ground, can you do that? That will able you to isolate the manufactured or wild leg. That coil needs 220 volts single phase to work probably +/- 20% it is just a coil, nothing but wound wire, that can be accomplished using any two legs of the 3 phase as long as they hit that number. As mentioned before it is best to keep that generated or wild leg out of the control circuit. Once we get the compressor to fire and run we will have to move wires around if it is running in the wrong direction.

Yes I do have a ground available for testing.
What would you like me to test first? The wild leg is L2 - white

 

[CITIZEN F16]

Yes I do have a ground available for testing.
What would you like me to test first? The wild leg is L2 - white

Number the wires L1, L2, and L3. Test each to ground and then pair them up, test L1, and L2 together, L2 and L3, and then L1 and L3. Your pictures still aren't getting a clear view of what he need. I still think the coil not getting proper voltage is the issue here. Using 240v in a control circuit is foreign to me, but I will do my best to help.

 

[Ltk]

.deleted post

 

[Ltk]

Number the wires L1, L2, and L3. Test each to ground and then pair them up, test L1, and L2 together, L2 and L3, and then L1 and L3. Your pictures still aren't getting a clear view of what he need. I still think the coil not getting proper voltage is the issue here. Using 240v in a control circuit is foreign to me, but I will do my best to help.

L1-L2 = 241v
L1-L3 = 243v
L2-L3 = 243v

L1-ground = 120v
L2-ground = 120v
L3-ground = 212v

Please ignore my last post as I didn’t have a good ground to reference for testing but I do now

Reading left to right:

Coil terminal 1-ground = 120v
Coil terminal 4-ground = 120v
Coil terminal 1-4 = 0.0v

 

[dalmatiangirl61]

Reading left to right:

Coil terminal 1-ground = 120v
Coil terminal 4-ground = 120v
Coil terminal 1-4 = 0.0v

I've been thinking about this for a few minutes, the only way I can see you getting 120v to ground on both terminals of coil, but 0v connected, is if both 120v lines are the same leg. I'd be tracing wires and drawing it out, something is not right, maybe one of the real Sparkys can chime in.

 

[CITIZEN F16]

L1-L2 = 241v
L1-L3 = 243v
L2-L3 = 243v

L1-ground = 120v
L2-ground = 120v
L3-ground = 212v

Please ignore my last post as I didn’t have a good ground to reference for testing but I do now

Reading left to right:

Coil terminal 1-ground = 120v
Coil terminal 4-ground = 120v
Coil terminal 1-4 = 0.0v

Unless you aren't making good contact with your meter if coil terminal 1-4 =0v there is one of your problems.
That means both those red wires came from the same line. The wild leg is L3, not L2 unless something else is fishy. The coil should run off of L1 & L2, the motor off L1,L2,L3. What you must have on that coil is L1,L1 or L2,L2 not L1,L2. What is the history of this compressor, did it ever run in it's current state?

 

[CITIZEN F16]

I have a feeling it isn't wired properly or even set up for a contactor that has a 220V coil. Is it possible this compressor came out of a shop that had 480v service? What is the motor voltage? Is it a dual voltage 240/480 motor? This is definitely getting to be a brain teaser, this should be used to test applicants for a maintenance electrician job. It doesn't look like that interlock is doing anything, or is it?
Are you around this thing all the time or is it an after hours project? I am in and out 24-7, I am self employed, I had a courier show up yesterday with items for a rush job, that is why I disappeared.


Can you make up a drawing of the wiring? If I am seeing it correctly there is only one wire to the on-off and one wire going in and out of the pressure switch and I don't see it going anywhere to make 240 volts to the coil. If it was 30+ tears ago you could call a Furnas distributor and buy a 120v coil of course no such luck. Those coils are interchangeable between different units I doubt anyone has one laying around any more.

 

[Ltk]

Unless you aren't making good contact with your meter if coil terminal 1-4 =0v there is one of your problems.
That means both those red wires came from the same line. The wild leg is L3, not L2 unless something else is fishy. The coil should run off of L1 & L2, the motor off L1,L2,L3. What you must have on that coil is L1,L1 or L2,L2 not L1,L2. What is the history of this compressor, did it ever run in it's current state?

Only one of the red wires goes from the coil to the L1 terminal. The other red wire goes to the side of the overload block down at the bottom.

So Could I simply jumper wire from L2 to terminal 4 on the coil also?

This compressor hasn’t ran in nearly 20 years, the barn/rats took it over. I’ve replaced most all seals and copper lines on the pump. The belts aren’t even hooked up yet as I’m still trying to get the wiring circuits figured out before putting it under load.

This compressor had a low-oil switch hooked to the pressure switch terminals and I unhooked that as it was smashed.

I have verified the motor leads are wired for low voltage operation that was my first step

 

[dalmatiangirl61]

You need to draw out a schematic, if you can't draw it out, then you do not understand how it works. Yes, this is like geometry class, you have to show your work and how you got an answer, you can't just be guessing and playing musical wires.

At this point your contactor nor coil is the confirmed problem, its the wiring. I have a bunch of Furnas contactors, pretty sure there is at least one Size 2, might even have a 110v coil. Sort your wiring.

 

[CITIZEN F16]

You need to draw out a schematic, if you can't draw it out, then you do not understand how it works. Yes, this is like geometry class, you have to show your work and how you got an answer, you can't just be guessing and playing musical wires.

At this point your contactor nor coil is the confirmed problem, its the wiring. I have a bunch of Furnas contactors, pretty sure there is at least one Size 2, might even have a 110v coil. Sort your wiring.

I think the problem is not getting 220v to the coil and I am at a loss on how it was originally done. The pictures don't tell the whole story maybe one straight a head and a ways back would work. Also why in the hell is the control circuit fused? If the motor has built in protection. I think I would replace it with a simple 3 pole 40 amp contactor
with out overloads, that is what I have, never an issue. My compressor is 240 volt single phase 7.5 HP. It looks like it was a cob job somewhere along the line. I have a feeling that contactor was not original equipment.

 

[CITIZEN F16]

You need to draw out a schematic, if you can't draw it out, then you do not understand how it works.

I built my own phase converter, everything made sense when I assembled it. 15 years or so down the road I decided to upgrade it with new components as a few of the capacitors started leaking. The wires looked like a big plate of spaghetti with no sauce. Thank God I saved my original design drawings, they were good to refresh the memory. It seems the older you get the longer it takes to get your head back in the game.

 

[SAF]

Compressor Control Circuit Wiring/Testing

Attached is a rough sketch of your control circuit connections. Your power wiring is connected correctly since you can manually get the motor to run manually, as long as the generated/wild leg stays on L2.

There is likely a problem with one of the control components. Sitting in a barn can allow oxides to build up on contact surfaces and cause them to be less conductive when inoperative, as you need contact arc to burn off the oxide buildup.

When testing refrain from testing to ground, this is mostly irrelevant as none of the controls or motor are referenced to ground. You need to do all testing from line to line, namely L1 and L3 in your case.

First thing to check is the control fuse. You should test from L3 to the top and bottom of the fuse. The top should be hot 240V, the bottom should read the same, if not the fuse is blown. This is likely due to you having low voltage at the start, then later dropping to no voltage. If its blown, test for a short circuit before replacing. A chattering contactor can also blow the fuse if it is sized closely to the coil draw.

The next things to test, again from the line voltage NOT GROUND.

ON/OFF switch, Its fed from the fuse L1 power leg, so one lead to L3 the other lead to both sides of the switch.

Pressure switch, also fed from L1 leg, so one lead to L3 the other lead to both sides of the switch. ON/OFF switch must be on.

Overload relay contacts, fed from L3, so one lead on L1 the other lead to both terminals of the overload contact.

Another issue that can cause chattering, to check last is the iron magnet assembly that is surrounding the coil. The contact faces can become rusty sitting in a damp location as they are raw steel lamination's. If this is the case the starter coil and magnet assembly will need to be disassembled to get the iron core out for cleaning. Clean the coil faces by lightly rubbing them against some very fine sand paper backed up with a flat piece of steel or glass. No excessive scrubbing or hand sanding. Blow the sanding dust dust off of all parts before reassembling the starter.

The coil should be good because it was trying to pull in while it was being supplied under voltage. just don't continue to let it chatter, it can overheat or continue to blow the fuse.

That should be enough to get you to the problem spot.