Compressor pressure switch wiring question

[TXNinAZ]

I bought a used Emglo compressor and replaced the 3 phase setup with a 5hp single phase motor and new mag starter. One last hurdle I've run into is wiring the pressure switch to the starter- I've searched and searched and everything I've found is slightly different to what I have, so I need some help. Where on this starter do the switch wires connect?

Grizzly starter:


Pressure switch:

 

[pattenp]

You use only one side of the pressure switch. So Line on PS to L1 on MS, and Motor on PS to coil (14) on MS. The pressure switch energizes the coil on the MS. In diagram, 14 is coil which is the same on your MS. 14 on your MS is N/O which is what you want to use.

Diagram
http://www.ccparts.net/Shihlin_diagram_pressure_switch_only.JPG


**** Edit: I'm starting to second guess myself on the connections. I'm sure there will be someone who will be more sure on the correct connections. ****



*

 

[wyliesdiesels]

You use only one side of the pressure switch. So Line on PS to L1 on MS, and Motor on PS to coil (14) on MS. The pressure switch energizes the coil on the MS. In diagram, 14 is coil which is the same on your MS. 14 on your MS is N/O which is what you want to use.

Diagram
http://www.ccparts.net/Shihlin_diagram_pressure_switch_only.JPG


**** Edit: I'm starting to second guess myself on the connections. I'm sure there will be someone who will be more sure on the correct connections. ****



*

Yeah i think u got a few things mixed up.

The diagram u linked to doesnt match the diagram he posted. The diagrams are for 2 different models as his doesnt have the same contact numbers or starter coil letters.

A is one side of the coil, B is the other. If u look at how the overload relay is wired to L1 and A, then it makes sense.

If u hooked up the pressure switch to L1, the coil wouldnt get 240v and it wouldnt work.

14 is a NO(normally open) aux contact NOT one side of the starter coil.

On his diagram 14 is NO, on yours 14 is marked NC(normally closed).

These aux contacts arent need in this situation. The OP doesnt need an aux contact because the pressure switch WILL continually provide power, on and off as it cycles, to the starter coil.

Wiring through a NO aux contact is needed when momentary controls such as non latching start buttons are used. Because a momentary start switch doesnt continually provide power, after being pushed, to keep the starter coil energized, a NO aux contact is used to keep power flowing to the starter coil. The NO contact becomes closed after the start button is pushed.

So the jumper from 14 to B needs to be removed. Then take a jumper from L2 or L3(whichever the OP uses as the second hot leg input) and connect it to one "Line" terminal on the PS. Take another wire jumper from the corresponding "Motor" terminal on PS and connect to B.

L2 or L3 ----> Line terminal on PS
Motor terminal on PS -----> B terminal on starter

EDIT: the above wont work with this starter because of the momentary start button which i originally didnt know this starter had.

 

[TXNinAZ]

Yeah i think u got a few things mixed up.

So the jumper from 14 to B needs to be removed. Then take a jumper from L2 or L3(whichever the OP uses as the second hot leg input) and connect it to one "Line" terminal on the PS. Take another wire jumper from the corresponding "Motor" terminal on PS and connect to B.

L2 or L3 ----> Line terminal on PS
Motor terminal -----> B terminal on starter

Thanks Wylie! What gauge wire for the pressure switch lines? I'm assuming even 14 gauge would be fine since it's not conducting 220v, but want to be sure. Here's where I am now:

 

[sselander]

there i chart here,
Thw Grizzly is a Sherndian Electric MP-30 magnetic starter
http://www.amazon.com/dp/B00ATCCYXK/?tag=atomicindus08-20

this may help also:
http://wiki.vintagemachinery.org/motor starter wiring diagrams.ashx

 

[TXNinAZ]

That raises a question, getting rid of the 14 connection- it looks like doing that removes the lower connection of the 'On' switch. How does it function with no jumper in place?

 

[wyliesdiesels]

Thanks Wylie! What gauge wire for the pressure switch lines? I'm assuming even 14 gauge would be fine since it's not conducting 220v, but want to be sure.

Actually it Depends on the coil load amperage not the voltage. But yeah i imagine that #14 should be fine.

That raises a question, getting rid of the 14 connection- it looks like doing that removes the lower connection of the 'On' switch. How does it function with no jumper in place?

Whoops my bad. I didnt realize that THAT was the ON button. There is no label on it. I was curious about that. My curiosity about that should've told my brain to look longer at it. Looks like since theyre using 13/14 which is NO contact, it most likely means that the ON button is a momentary/non latching type. Can u tell if it is?

If it is INDEED a momentary/non latching button, then it changes things.

 

[TXNinAZ]

Actually it Depends on the coil load amperage not the voltage. But yeah i imagine that #14 should be fine.



Whoops my bad. I didnt realize that THAT was the ON button. There is no label on it. I was curious about that. My curiosity about that should've told my brain to look longer at it. Looks like since theyre using 13/14 which is NO contact, it most likely means that the ON button is a momentary/non latching type. Can u tell if it is?

If it is INDEED a momentary/non latching button, then it changes things.

Seems to be momentary- pushing it in just makes a spring noise and it returns to the same position.

 

[wyliesdiesels]

Ok i found the manual for it.

Did this starter come with the compressor?

 

[TXNinAZ]

Ok i found the manual for it.

Did this starter come with the compressor?

No, I bought it and the motor to convert from 3 phase. The pressure switch is the same one that was on it originally.

 

[manwithtools]

Interesting as well that the diagram only shows using two overload contacts, normally doing that on a three phase overload will result in a phase imbalance and the overload will trip.

To work around that usually in a single phase use of a three phase overload you would run L1 through the first overload contact and then L2 would run in series through the second and third overload contacts.

Could be that this overload does not sense the phase imbalance...

 

[wyliesdiesels]

No, I bought it and the motor to convert from 3 phase. The pressure switch is the same one that was on it originally.

Unfortunately Its the wrong starter for the application due to having start stop buttons.

If i had seen the starter cover, i wouldve said this earlier in the thread.

This type of starter would be good for an application such as a conveyor belt.

A motor that is operated by a pressure switch needs to have a OA(off-auto) switch, which is basically a latching single pole switch.

The momentary/non latching start button and latching stop button arent gonna work with the pressure switch.

U COULD modify it and remove the start button from the circuit by removing jumpers but then u need a latching switch in series with the pressure switch.

And if u modified it, then the U/L listing is violated.

I would buy a different starter. Its more work to modify the starter than it would be to get the correct starter.

Interesting as well that the diagram only shows using two overload contacts, normally doing that on a three phase overload will result in a phase imbalance and the overload will trip.

To work around that usually in a single phase use of a three phase overload you would run L1 through the first overload contact and then L2 would run in series through the second and third overload contacts.

Could be that this overload does not sense the phase imbalance...

Yes, this is a basic overload relay that does NOT have phase loss detection.

 

[TXNinAZ]

Unfortunately Its the wrong starter for the application due to having start stop buttons.

If i had seen the starter cover, i wouldve said this earlier in the thread.

This type of starter would be good for an application such as a conveyor belt.

A motor that is operated by a pressure switch needs to have a OA(off-auto) switch, which is basically a latching single pole switch.

The momentary/non latching start button and latching stop button arent gonna work with the pressure switch.

U COULD modify it and remove the start button from the circuit by removing jumpers but then u need a latching switch in series with the pressure switch.

And if u modified it, then the U/L listing is violated.

I would buy a different starter. Its more work to modify the starter than it would be to get the correct starter.



Yes, this is a basic overload relay that does NOT have phase loss detection.

Ugh that's what I was afraid of. What do you think of this one? Would it work?

 

[wyliesdiesels]

Well without looking it up(will do in a minute) that one will probably work however, are u gonna be using it outside in the rain?

Its rated NEMA 4x and Im sure much of the high price is because of the nema 4x rating.

https://www.nema.org/Products/Documents/nema-enclosure-types.pdf

 

[TXNinAZ]

Well without looking it up(will do in a minute) that one will probably work however, are u gonna be using it outside in the rain?

Its rated NEMA 4x and Im sure much of the high price is because of the nema 4x rating.

https://www.nema.org/Products/Documents/nema-enclosure-types.pdf

Honestly just looking for something that will mount to my motor that has a switch on it. At this point, I'm tempted to call my local compressor service company to bring one and install it- very frustrated.

 

[wyliesdiesels]

Honestly just looking for something that will mount to my motor that has a switch on it. At this point, I'm tempted to call my local compressor service company to bring one and install it- very frustrated.

Its really not that hard.

U had the inclination to ask the questions and understood some of the wiring basics.

Just gotta have the right parts.

I wouldnt waste the $ on someone to install a unit for u. U can do it!

 

[TXNinAZ]

Its really not that hard.

U had the inclination to ask the questions and understood some of the wiring basics.

Just gotta have the right parts.

I wouldnt waste the $ on someone to install a unit for u. U can do it!

Not a matter of difficulty- it's a matter of getting it done. Can't find anyone local that has mag starters for compressors. Everyone I've called caters to industrial customers or wants $200+ for a NEMA starter.

 

[TXNinAZ]

So now that I think about it, could I reuse the 3 phase starter for the time being?

 

[manwithtools]

Either starter you have will work. The one you started the post with will be the easiest. I'll try to post more info later. The old three phase would work but you would have to get the right overload heaters. Might or might not be available readily.

Sent from my SM-G920V using Tapatalk

 

[wyliesdiesels]

Either starter you have will work. The one you started the post with will be the easiest. I'll try to post more info later. The old three phase would work but you would have to get the right overload heaters. Might or might not be available readily.

Sent from my SM-G920V using Tapatalk

Yes either will work but the first one requires some reconfiguring.

The second one is DP(definite purpose) which might be unserviceable- ie. cant change coil or contacts, etc

 

[TXNinAZ]

Yeah looks like the heaters are way too small:

 

[TXNinAZ]

Either starter you have will work. The one you started the post with will be the easiest. I'll try to post more info later. The old three phase would work but you would have to get the right overload heaters. Might or might not be available readily.

Sent from my SM-G920V using Tapatalk

Please share your suggestions. I'd love to make this work with what I've already purchased- value is running out on my money-saving used compressor :-(

 

[manwithtools]

Okay, here we go using the Shendian motor starter shown:

Assuming that the picture and wiring diagram on your first post is CORRECT then this what I would do:

Remove the manual start switch (part number 4 in the exploded diagram) along with ALL the flat metal jumpers associated with that switch.

Leave the wire with the ring terminal from 14 to B.

Connect a wire from T/5/L3 to one of the "Line" terminals on your pressure switch.

Connect anther wire to the "Motor" terminal on the pressure switch (be sure to use the one directly across from the "Line" terminal that you hooked to previously) to the 14 terminal on your motor starter - be sure the wire from 14 to B is still connected.

What you are doing is replacing the manual start switch with the pressure switch. Since the pressure switch is closed during the entire time the compressor pressure is less than the pressure set point it will power the coil on the motor starter (the equivalent of "pressing the start button" on the previous manual starter configuration). Once it reaches the set point pressure the pressure switch will open and the motor starter will open as well- stopping the compressor motor.

If this does not work, either the diagram is incorrect or something in the circuit is defective. 14ga should be fine, I'd use red if you have it available since this is a control circuit.

Let us know how it goes!

 

[wyliesdiesels]

If u go with the above u should add some kind of inline O/A(off/auto) switch so u can shut it off.

Also, how far away is the breaker panel and is it within sight?

If farther than 50' and not within sight, then a disconnect is required and could function as your on off switch.

Also, dont forget to set the thermal overload to the correct setting. Otherwise your motor could burn up.

 

[manwithtools]

Any luck? Was looking for the OP to reply with "Success!" BTW, Wyliesdiesels makes a good point abut the "Auto/Off" switch, we can help with that too if you need it.

 

[TXNinAZ]

Any luck? Was looking for the OP to reply with "Success!" BTW, Wyliesdiesels makes a good point abut the "Auto/Off" switch, we can help with that too if you need it.

Stuck with other work. Should have a round up post tomorrow some time. Will definitely need a shut off of some kind rather than the breaker.

 

[nsula_country]

Your shut off could be as simple as a HD (heavy duty, not Home Depot) light switch in a handy box inline with the coil.

I'd use a industrial controls selector switch mounted thru the starter enclosure. Example would be an Allen-Bradley 800T or 800H 2 position maintained selector switch or push-pull switch.

CT

 

[TXNinAZ]

Success!!! I didn't want to go without on the shutoff and wanted everything as simple as possible, so I bought a new starter. Lesson learned, but now all is well. I am wondering if my belt is too loose- don't think it's slipping, but I'm new to this.

https://vimeo.com/145578401

 

[manwithtools]

Glad you got it going. I'm not sure about the belt, although it looks fine to me. A little "give" in the belt is okay. Not so much that it slips of course, but not so tight that it cant flex is fine.

 

[TXNinAZ]

Glad you got it going. I'm not sure about the belt, although it looks fine to me. A little "give" in the belt is okay. Not so much that it slips of course, but not so tight that it cant flex is fine.

Thanks! I'll keep an eye on it and see if it loosens as it wears in a bit. I think I'll be happy with the upgrade [emoji3]

 

[wyliesdiesels]

Nice job.

Just out of curiosity what model starter did u get? It may help someone in the future when they stumble on your thread...

And u could have saved a few bucks by using FMC instead of LT but still looks good!

 

[TXNinAZ]

Nice job.

Just out of curiosity what model starter did u get? It may help someone in the future when they stumble on your thread...

And u could have saved a few bucks by using FMC instead of LT but still looks good!

I ended up with the Elimia one I posted earlier. After drilling holes in the back of the box to run wires through from the motor (didn't want to wall mount it) it wired up very easily. The LED lights up when it's switched to auto and off when off. Very happy with it, and it's put together in Alabama, which is a nice bonus. Call direct to get a bit better deal than eBay.

 

[wyliesdiesels]

The enclosure is overkill but it works.

 

[TXNinAZ]

The enclosure is overkill but it works.

Definitely, but oh well.

 

[Emsand1]

Okay, here we go using the Shendian motor starter shown:

Assuming that the picture and wiring diagram on your first post is CORRECT then this what I would do:

Remove the manual start switch (part number 4 in the exploded diagram) along with ALL the flat metal jumpers associated with that switch.

Leave the wire with the ring terminal from 14 to B.

Connect a wire from T/5/L3 to one of the "Line" terminals on your pressure switch.

Connect anther wire to the "Motor" terminal on the pressure switch (be sure to use the one directly across from the "Line" terminal that you hooked to previously) to the 14 terminal on your motor starter - be sure the wire from 14 to B is still connected.

What you are doing is replacing the manual start switch with the pressure switch. Since the pressure switch is closed during the entire time the compressor pressure is less than the pressure set point it will power the coil on the motor starter (the equivalent of "pressing the start button" on the previous manual starter configuration). Once it reaches the set point pressure the pressure switch will open and the motor starter will open as well- stopping the compressor motor.

If this does not work, either the diagram is incorrect or something in the circuit is defective. 14ga should be fine, I'd use red if you have it available since this is a control circuit.

Let us know how it goes!

I know this is old but huge shout out for the correct answer.

I got a pieced together 60 gallon compressor for free including delivered. That's the end of the good. Found it had a 2hp motor with a Harbor Freight 5hp required pump.

I bought a 5hp motor and discovered what electric magnetic starters are and why I needed one.

Bought a Big Horn 220v 5hp starter, which is the same used by Grizzly. I tried dozens of suggestions and this one worked!!!!