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Old 04-23-2009, 06:58 PM   #1
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Default HOA and Contactor

First off Hello everybody new member here.


so i have this HOA and contactor that sends 240v to a Air Dryer. when i turn the switch to hand the contactor won't energize. I am getting control voltage from the control transformer of 120v but the contactor is not seeing this. what am i missing???

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Old 04-23-2009, 07:45 PM   #2
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Quote:
Originally Posted by clos View Post
First off Hello everybody new member here.


so i have this HOA and contactor that sends 240v to a Air Dryer. when i turn the switch to hand the contactor won't energize. I am getting control voltage from the control transformer of 120v but the contactor is not seeing this. what am i missing???
...A schematic.

I suspect that you may only need to add one wire. Many Motor starters with a (Hand - Off - Auto) switch need to be field wired. Is this a new installation that you are commisioning, or servicing an existing one in place?

Your H-O-A switch probalby has (2) sets of cantacts, one set will only be closed when the switch is in HAND, and the other set will be closed only when the switch is in AUTO, lastly, both contacts will be open when in the OFF position.

If AUTO is working that means that the circuitry for the auto side is complete. You may just need a provide a "hot" on the HAND side of the switch, or if that exists, then you may only need a jumper on the switched side of the contacts, so the the motor starter coil gets power when the switch is in HAND position.

If no schematic exists, pencil one up. Just moving wires around is a risky adventure. Have a plan, and execute the plan, that always works. Plus a schematic is invaluable for service years in the future.

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Old 04-24-2009, 09:13 AM   #3
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Quote:
Originally Posted by IMM_Doctor View Post
...If no schematic exists, pencil one up. Just moving wires around is a risky adventure. Have a plan, and execute the plan, that always works. Plus a schematic is invaluable for service years in the future.

Now that is GOOD ADVICE! How many times have you gone behind someone that has taken things all apart to "fix" it, only to find they have no idea how to even get back to where they started.

In order to answer what is wrong, some more info would be needed, as was stated in the last post we would need to know...
  • Is this a new or existing install?
  • If existing, when did it stop working, and what else happened?
  • Is there OL protection?
  • Does the dryer work in Auto?
  • Is there a schematic, if so where does the control voltage "stop" between the transformer and contactor coil?
There are many here that are willing and able to help, we just need some more info to do so!
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Old 04-25-2009, 01:18 PM   #4
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As the other guys more or less said, I think you have about a 50/50 chance that "hand" was never wired up. I know I've wired up starters that way purposely for various reasons. Get your meter out and find where the control voltage stops. That's sorta step #1 in troubleshooting most things.
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Last edited by MDShunk; 04-25-2009 at 01:24 PM.
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Old 04-25-2009, 01:31 PM   #5
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Now that is GOOD ADVICE! How many times have you gone behind someone that has taken things all apart to "fix" it, only to find they have no idea how to even get back to where they started.

In order to answer what is wrong, some more info would be needed, as was stated in the last post we would need to know...
  • Is this a new or existing install?
  • If existing, when did it stop working, and what else happened?
  • Is there OL protection?
  • Does the dryer work in Auto?
  • Is there a schematic, if so where does the control voltage "stop" between the transformer and contactor coil?
There are many here that are willing and able to help, we just need some more info to do so!
this is an existion installation. The MCC is sending 480v to the control transformer, which is stepping down to 120v. Load side out of the contactor is 240v to a snap disconnect switch. for the switch it goes to the Air dryer, which has a transformer as well. I think i have a two-fold problem because on one leg of the 480 it is blowing fuses. I replaced the controll transformer in the MCC and replaced all wires after labeling them back like there were hooked up. but when i turn it on to HAND the contactor will not suck in, but if i push in on the contactor with a screwdriver it will send power to the snap switch. The Contactor will not work in HAND OR AUTO. The only OL protection is the 4amp fused inline with the 480 coming in and there is a 3 amp block fuse protecting the contactor.

MY background is that i came up through commercial instalations, tenent finish and remodles. My motor controll troubleshooting is weak , but my regular troubleshoogint skills are good.

Can the heaters or the overloads on the contactor be the cause of this.
I have a co worker who is an ass and thinks he knows everything and at every chance he gets tries to be the TOP ELECTRICIAN and i would not put it past this guy to sabatoge. but that is another story all together so i have to contend with that theory too, I left it all pulled apart and went to lunch and when i came back some of my brady tags looked like they were starting to come off.

thanks
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Old 04-25-2009, 02:02 PM   #6
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Quote:
Originally Posted by clos View Post
First off Hello everybody new member here.
welcome to the forum.
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Old 04-25-2009, 03:17 PM   #7
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Quote:
Originally Posted by clos View Post
this is an existion installation. The MCC is sending 480v to the control transformer, which is stepping down to 120v. Load side out of the contactor is 240v to a snap disconnect switch. for the switch it goes to the Air dryer, which has a transformer as well. I think i have a two-fold problem because on one leg of the 480 it is blowing fuses. I replaced the controll transformer in the MCC and replaced all wires after labeling them back like there were hooked up. but when i turn it on to HAND the contactor will not suck in, but if i push in on the contactor with a screwdriver it will send power to the snap switch. The Contactor will not work in HAND OR AUTO. The only OL protection is the 4amp fused inline with the 480 coming in and there is a 3 amp block fuse protecting the contactor.

MY background is that i came up through commercial instalations, tenent finish and remodles. My motor controll troubleshooting is weak , but my regular troubleshoogint skills are good.

Can the heaters or the overloads on the contactor be the cause of this.
I have a co worker who is an ass and thinks he knows everything and at every chance he gets tries to be the TOP ELECTRICIAN and i would not put it past this guy to sabatoge. but that is another story all together so i have to contend with that theory too, I left it all pulled apart and went to lunch and when i came back some of my brady tags looked like they were starting to come off.

thanks
This website just might help ...(google) hand off auto motor controls ....clic on motor starters start stop H .O .A .....(exman .com/mshoas.html motor control 101
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Old 04-25-2009, 03:46 PM   #8
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Quote:
Originally Posted by clos View Post
Can the heaters or the overloads on the contactor be the cause of this.
I have a co worker who is an ass and thinks he knows everything and at every chance he gets tries to be the TOP ELECTRICIAN and i would not put it past this guy to sabatoge. but that is another story all together so i have to contend with that theory too, I left it all pulled apart and went to lunch and when i came back some of my brady tags looked like they were starting to come off.

thanks
The OL (heater) block has a set of contacts that opens up when an overload occurs. These contacts can be automatic to reset (spring loaded), or they may need to be manually reset. In most applications this set of contacts opens up the neutral going to the contactor coil. I would check that set of contacts, make sure they are reset, and then check them with a meter. if these are fine, trace your circuit from the control transformer, to the HOA switch, and on to the coil.....where do you lose your voltage? Does your neutral make it to the other side of the coil?

Let us know how you make out....GOOD LUCK!
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Old 04-25-2009, 04:00 PM   #9
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Will do i will be back to work on monday to do more trouble shooting on the thing.
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Old 06-19-2009, 12:33 PM   #10
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Originally Posted by IMM_Doctor View Post
...A schematic.
If no schematic exists, pencil one up. Just moving wires around is a risky adventure. Have a plan, and execute the plan, that always works. Plus a schematic is invaluable for service years in the future.
Such good advice. It's to bad most electricians/maint techs have no clue about drawing there own projects. I have no idea how anyone can wire any control logic without a schematic. If one does not exist, draw one, then implement the drawing. How do you create a parts list without a drawing?
We always prepared our own schematics and passed them around to other electricians for feedback. It's so much easier when you have a plan in advance. If it works on paper it will work in the application.

Ever heard an electrician say "I will make the drawing after I'm done"? It makes me cringe.

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