Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 12-14-2009, 10:12 AM   #46
Newbie
 
Join Date: Dec 2009
Posts: 24
Share |
Default

Older air compressor wiring help


Ok.

Just ordered it. I will go with the light switch. Thanks for the advice. I will let you know when I get it.

lash-1295 is offline   Reply With Quote
Old 12-14-2009, 12:09 PM   #47
Member
 
Join Date: Jun 2007
Posts: 3,506
Default

Older air compressor wiring help


Quote:
Originally Posted by nap View Post
You wire it how you want to wire it and I wire it how I like.

Okay

If you put the air pressure switch in the wrong place, it will drop out the coil and you would need to hit the start button to restart the machine.

Not the way I described it.
Using no start/stop buttons or switches, when the compressor needs air, it closes the pressure switch. The pressure switch energizes the starter coil. The starter then starts the motor.
When the compressor reaches the correct pressure, the pressure switch opens and drops out the starter coil. This stops the motor. It is now ready for the next cycle. Its called "automatic".

That is where I would put the oil pressure switch so I would have to restart the machine manually for the loss of oil pressure since that is something the operator should attend to.

This I agree with somewhat, but it is not necessary. The oil pressure switch (In series with the pressure switch) will open on low pressure and drop out the starter. This will stop the motor. The only way the motor can be restarted is if the low oil pressure situation is resolved. This involves operator attendance just as a reset would. No difference.

with the air pressure, you would want the compressor to cycle on and off as needed. Like I said, if you put that in the wrong place in the circuit, it will not do that.

What wrong place? You have a pressure switch an oil pressure switch and the motor starter. This is a simple series circuit. Of course you can put the pressure switch in parallel with some creative wiring, but the oil pressure switch must be in series with the starter coil. So common sense says to put them in series. Yes, the pressure switch closes on low air pressure and opens on preset pressure. (Usually). The pressure switch operates the starter coil directly. Thus, cycling the motor on and off as required. "auto"

as to requirement for on/off. How do you propose turning it on and off?

3 ways. 1) The pressure switch. "normal operation" 2) The oil pressure switch. " low oil pressure" 3) The possible requirement for a disconnect in front of the starter.

I do not like to use breakers for switches.

Same here.

I would not plug this in so that means I would put an on/off switch on the thing.

Just because its hard wired does not mean it requires a start/stop. You could put one in if you wanted to, but it is not required. In my wiring scheme, the breaker is turned on and never touched again. Unless it trips for some reason.

a disconnect may or may not be required but that would depend on where the breaker is from the compressor. If you need a disco, I would use a combination starter/disco.
Agree on both points. Combination starters cost ALOT of money. A simple AC disconnect like used outside next to a condenser unit would work just fine and cost less than $20.00.

I had no intention to hijack or disrupt this thread. However, there was some clarification required between nap and myself before I could let it go. Thanks and good luck on this project.
J. V. is offline   Reply With Quote
Old 12-14-2009, 12:41 PM   #48
Member
 
Join Date: May 2009
Location: Brooklyn, New York (NYC)
Posts: 1,124
Angry

Older air compressor wiring help


Quote:
Originally Posted by nap View Post
a motor starter only comes with a stop start button if that is how you order it. There are many times where I have a motor starter and the stop start station is nowhere near the motor starter so having one on the starter is an unnecessary expense.

A lot of times, there will be an on/off/auto selector on a motor starter as well but again, only if it is needed or wanted.

when operating motors with other controls, having a stop start on the starter is not the norm.
So I've come across one where it was operating with an automatic sensor on a forced air system. In addition it had an ON/OFF/Auto combination. And it was wired wrong, anyway. One of my supervisors said he knows 100% that it's a burned coil. So, on blind faith I went out and got another coil. Installed the coil and it still didn't work. That's when I REALLY started checking. Found an open circuit in the sensor. And the magnetic starter was wired wrong. Pressing the manual ON button didn't do a thing.

Last edited by spark plug; 12-14-2009 at 12:43 PM. Reason: Grammatical error
spark plug is offline   Reply With Quote
Old 12-14-2009, 01:51 PM   #49
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 5,005
Default

Older air compressor wiring help


I might as well jump into the fray..... My opinion is that with this compressor a hard wire installation is best.... it isn't likely to be portable. Second IMO the manufacturer had a start stop button option on the starter like the image previously posted.... That doesn't mean it was required. It is prudent to have a stop ability at the air compressor so that you have a readily available stop if your going to have your hands around those moving parts of the pulley and belt during maintenance. At any rate I think a disconnect would be prudent.. close by, at the least, and I think this has been suggested already by JV.
The problem with air compressors is their ability to restart without warning. No matter how you wire it this auto start is inherent to the compressor but I sure as heck would want to have a stop ability where I could reach it if I was doing maintenance on the thing or if I just wanted to turn it off after use.

Anyway here is a pretty good one to try and get. Nema 1 starter .. with start/stop kit installed.... might give the seller a call and make sure of coil voltage should state Vo3 if 240 volts. But 120 volt coil wouldn't be a big deal either.It should have Class 20 overloads. Square d web site I would think have all the info on this starter...I'd just search class 8536.

This is a 3 pole starter and I believe it will start a single phase 5 hp if you configure it correctly..which is pretty simple . The original one on the compressor is a 3 pole starter configured with a nifty kit to single phase. There was a mounting block that could be added to the right of the coil that housed the other two overloads when used as 3 phase contacter.


http://cgi.ebay.com/Square-D-Nema-si...%3D4%26ps%3D63
__________________
" One nice thing about the NEC articles ... you have lots of choices"

Stubbie

Last edited by Stubbie; 12-14-2009 at 03:07 PM.
Stubbie is offline   Reply With Quote
Old 12-14-2009, 03:09 PM   #50
Newbie
 
Join Date: Dec 2009
Posts: 24
Default

Older air compressor wiring help


Well since I am the guy who asked for help in the first place I guess I am in no position to be the expert here, but when I ordered the switch I asked if they thought I should order the start/stop switch. The tech said that I didn't need it and it would not work correctly for a compressor anyway. I didn't press him for details but I asked him about MM's suggestion of a light switch and he said that is what he would use instead of the on/off switch. Don't mean to take sides just relaying what I was told. Thanks for all the help. I could have bought a 120v coil locally for $40 and I though about it but adding the proper heaters would have brought it up to the same price not to mention it will be nice having a wiring diagram (if I can read it) LoL. I am hoping I can wire it up and just let you guysf look at pictures and verify my work. I sure can't wait to get this thing done so I can get back to work on the 68 Mustang convertible that is the reason for this compressor in the first place.
lash-1295 is offline   Reply With Quote
Old 12-14-2009, 03:43 PM   #51
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 5,005
Default

Older air compressor wiring help


Sorry lash I just saw where you have ordered your starter. I'm not sure what the tech was saying about a start/stop not working correctly. But I don't want into that argument.

Hopefully there won't be any other issues with your air compressor once you get the new starter installed.
__________________
" One nice thing about the NEC articles ... you have lots of choices"

Stubbie
Stubbie is offline   Reply With Quote
Old 12-14-2009, 03:59 PM   #52
Newbie
 
Join Date: Dec 2009
Posts: 24
Default

Older air compressor wiring help


Dang, I wish I had seen that one before I ordered. Especially if it stays cheap. If you haven't guessed I am trying to do this as cheaply as possible. Don't know how I missed that one. Thanks anyway Stubbie
lash-1295 is offline   Reply With Quote
Old 12-14-2009, 04:19 PM   #53
nap
You talking to me?
 
nap's Avatar
 
Join Date: Dec 2007
Location: sw mi
Posts: 5,407
Default

Older air compressor wiring help


Quote:
Originally Posted by Stubbie View Post
Sorry lash I just saw where you have ordered your starter. I'm not sure what the tech was saying about a start/stop not working correctly. But I don't want into that argument.
.
I would think the guy was speaking of the 3 wire stop/start configuration.

speaking of; do you have any diagrams with a 3 wire SS station with an air pressure switch involved so as to not reset the SS function? I went to PM's with JV to discuss and need a diagram showing what I was speaking of doing.

oil pressure acts same as "stop"

air pressure does not drop out the run circuit but does shut down the compressor


yes, extra relay as far as I see it. but hey, it's just another rung on the ladder, right?

and your drawings are sooooo nice.
nap is offline   Reply With Quote
Old 12-14-2009, 05:56 PM   #54
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 5,005
Default

Older air compressor wiring help


Sorry NAP stepped out for Pizza and hot wings....

Nope I don't have that exact diagram....Just looked for one in my files. I have several 3 wire control drawings though with latching circuits that are generic circuits. Meaning I do not show exact wire connections at the starter as it varies considerably. But I did post one that is close at the end of this post.

But essentially what you would do is place you pressure switch with L1 going to your stop button and L2 going to one side of your starter coil. The oil pressure switch would be in series with the stop circuit. I think that is what you are wanting. This would energize the coil when you push start which is a momentary switch. This pulls in the starter coil and closes the auxillary contact on the starter that completes the latch circuit. When you release start... the latch circuit will continue to hold the coil in and run the motor. The latch circuit must be broken to stop the motor/compressor. That will happen if the oil pressure switch opens or the stop button is pushed. But better to have the oil pressure switch kill all power to the control circuit.... So place it in series with the stop button and it will be mechanically opened by a low oil float and shaft. If it opens then the motor stops and you cannot start the motor until the oil switch issue is resolved. Once it is you simply push start and your up and running again. You would not reset anything on the run circuit.

The closest I could get to a drawing of your circuit is this one for a dust collector like below just consider the high dust switch your oil pressure switch. Unfortunately this is a low voltage 3 wire control and not 240 volt coil. So not quite correct. Maybe will get your point across. What you are describing is very likely what you would find in a commercial or industrial setting controlling the air compressor if you wanted several start/stop stations located remote from the compressor or even just one at the compressor. Even though this shows a definite purpose 3 pole contactor it really is functioning the same as a motor starter it's just using a pole of the contactor to latch the circuit...whereas a magnetic motor starter would use a auxillary contact. Your pressure switch would be in the place of the transformer controlling a 240 volt coil.
Attached Thumbnails
Older air compressor wiring help-3-wire-control-1.jpg  
__________________
" One nice thing about the NEC articles ... you have lots of choices"

Stubbie

Last edited by Stubbie; 12-14-2009 at 06:25 PM.
Stubbie is offline   Reply With Quote
Old 12-14-2009, 07:19 PM   #55
Member
 
Join Date: May 2009
Location: Brooklyn, New York (NYC)
Posts: 1,124
Thumbs up

Older air compressor wiring help


Stubbie (Poster #49) You mention that it would be worthwhile to "Hardwire" the compressor. also, that compressors have a tendency to suddenly start. And that while doing maintenance it would be good to have a cutoff switch, such as the OFF button on the magnetic starter. First off, the reason the compressor starts "Suddenly", is when it's controlled by the pressure switch (connected in parallel with the coil) and the pressure drops to allow the compressor to run. For this very reason, IMHO it's not sufficient to rely on the magnetic starter alone. You would need a separate Manual cutoff switch "within sight". I'm not sure but I think this is also a Code requirement.
spark plug is offline   Reply With Quote
Old 12-14-2009, 07:24 PM   #56
nap
You talking to me?
 
nap's Avatar
 
Join Date: Dec 2007
Location: sw mi
Posts: 5,407
Default

Older air compressor wiring help


an off switch in the situation you just stated is not a legal disconnect. A disco must cut the power that runs the unit altogether. If the breaker is deemed appropriate as a disco (distance, line of sight, lockable, whatever), in the discussion involved, that would be the only disco in the system so far.
nap is offline   Reply With Quote
Old 12-14-2009, 07:37 PM   #57
Member
 
Join Date: May 2009
Location: Brooklyn, New York (NYC)
Posts: 1,124
Red face

Older air compressor wiring help


Stubbie (Poster #54) When I first posted (#55) I did not read (yet) your post #54. That is the ideal way to wire a control circuit on a compressor (or similarly any other piece of equipment. But I encountered a problem where, a magnetic starter was miswired. And it took some effort (removing the cover and tracing the wiring) to find the problem. That the automatic connection (a sensor) was wired to the manual override button (which is a momentary switch). And everyone wondered why the blower doesn't work.

Last edited by spark plug; 12-14-2009 at 07:40 PM. Reason: clarification of posting ("another"/"any other"
spark plug is offline   Reply With Quote
Old 12-14-2009, 08:53 PM   #58
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 5,005
Default

Older air compressor wiring help


Nap is correct a unit switch on the compressor that does not open both hot conductors is not a legal disconnect even if another disconnecting means is present. But its a legal....off/stop ! ...... However all joking aside in a residential garage I'd just use the breaker if I was going to work on the thing. You could lock the breaker in the open position if needed...or a simple AC disconnect works...close by....... but I like the Hubbell ones that are really expensive with the red off handles and horn that sounds on delay if the disconnect is fooled with..... Whoops guess I'm still joking.

My point is I want a stop/start option on the air compressor but that's me and some people say I'm weird...
__________________
" One nice thing about the NEC articles ... you have lots of choices"

Stubbie
Stubbie is offline   Reply With Quote
Old 12-14-2009, 11:07 PM   #59
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 5,005
Default

Older air compressor wiring help


Nap

I left out a rather important feature of the start /stop switch ( I think). I believe this type switch is an assembly and comes with a relay designed for use with a air pressure switch. Not just any ole start /stop button. It has a contact in the relay that closes when the start switch is pushed which stays energized until you push the stop button. This is what allows the start switch to be momentary and still allows the pressure switch to cycle the motor once you release it. The diagram as shown would not allow the pressure switch to cycle the motor. Sorry for that omission it might be best if I draw the circuit maybe in the next few days as my example drawing just isn't showing what your wanting.
__________________
" One nice thing about the NEC articles ... you have lots of choices"

Stubbie

Last edited by Stubbie; 12-14-2009 at 11:35 PM.
Stubbie is offline   Reply With Quote
Old 12-15-2009, 12:00 AM   #60
nap
You talking to me?
 
nap's Avatar
 
Join Date: Dec 2007
Location: sw mi
Posts: 5,407
Default

Older air compressor wiring help


How I would do it:

the 3 wire start stop operates an aux relay but does have the motor overload in series. paralled with the start contact, a N/O contact from the aux relay and the oil pressure switch.

then, in another circuit I would series the oil pressure switch, a N/O contact from the relay (listed above) and the motor starter coil.

that way, the oil pressure or the stop switch would drop out the latched aux relay but the oil pressure switch would cycle the motor starter coil without dropping out the latched start stop circuit.



http://public.bay.livefilestore.com/...2.jpg?download

what do you think? (not considering the quality of the drawing)

Now, if he has an electric unloader, we can work that in so the comp runs continuously but dumps the loader when high pressure is reached. We can even figure in a timer so it will only run unloaded for 5 minutes or so and then shut down the motor (but leaves the latched circuit energized still so the system will still cycle automatically)? Huh?? maybe?


Last edited by nap; 12-15-2009 at 12:04 AM.
nap is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Outlet With Swith and Older (White, Black, Red) Wire CaptChaos Electrical 18 09-14-2009 11:17 PM
Older GE Fridge no Ice WorldOfJohnboy Appliances 3 09-10-2009 07:39 PM
Older building renovation and repair in ND. rickwesh Project Showcase 3 07-30-2009 11:03 PM
Question about replacing load center in older house speedster1 Electrical 5 05-14-2009 07:55 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.