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Author Topic: Transfer switch problem????  (Read 1096 times)
Iver
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« on: July 13, 2012, 12:27:12 AM »

    When hooked to the power pole, (30amp service), the power enters the coach through a 50 amp cable with a 30 amp adapter.  The power then goes through a surge suppressor, a transfer switch and then on to the main service including a 3k watt inverter/charger.  So far everything is fine.  Charger works fine.
However, as soon as I put a load on from the A/C for example, the A/C runs for 5 minutes and then the transfer switch opens, shuts power to the coach for around 15 seconds, then closes again supplying power for 15 seconds and then shuts the power off again.  And the cycle continues...
     I have an auto-winding power cable setup as well.  Is this a transfer switch problem?
Any thoughts??   Thanks, Iver.
   
 
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« Reply #1 on: July 13, 2012, 05:05:39 AM »

      Brand and model # of the inverter?  Just a WAIG from me, but it seems to me that there's a good chance that the transfer switch is fine but it's being "triggered to switch" by something else.  Maybe it's seeing power dropping off, maybe there's an intermittent connection someplace, etc.  Hard to tell exactly, but that's a possibility I'd keep in mind.
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Bruce H; Wallace (near Wilmington) NC
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Sam 4106
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« Reply #2 on: July 13, 2012, 07:19:00 AM »

Hi Iver,

It sounds to me like a loose neutral connection at or ahead of the transfer switch. If the the coil that engages the transfer switch looses power it will disengage. If you have a loose connection it will heat up and loose contact. Check all the connections on the transfer switch, cord reel, slip rings, and power cord plug. You could also hook up a temporary cord from an outlet directly to the input on the transfer switch and see if you have the same problem.

Good luck, Sam
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« Reply #3 on: July 13, 2012, 07:21:39 AM »

Is the main transfer switch causing issues, or a transfer switch inside the inverter?  If the transfer switch is inside the inverter then the inverter might be shutting down due to power overload.  My front air conditioner was wired through my Prosine 3.0 and during super high temps the air conditioner would draw so much power that the inverter would reset even though the power was just passing through the inverter.
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robertglines1
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« Reply #4 on: July 13, 2012, 07:29:24 AM »

need to verify your grounds       common ----  earth ground  ----  you have allot going on there especially with adapters and connections.  some connections can loose up to 10%  the more you have.   ch voltage and ground orientation at a wall outlet.  also your power supply at pole might not have proper grounding.  Just a few of the things that can go wrong. Has system worked properly in past? If so ck see if pole is protected by gfi.   Bob    
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Sean
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« Reply #5 on: July 13, 2012, 11:17:17 AM »

...  The power then goes through a surge suppressor, a transfer switch and then on to the main service including a 3k watt inverter/charger.  So far everything is fine.  Charger works fine.
However, as soon as I put a load on from the A/C for example, the A/C runs for 5 minutes and then the transfer switch opens, shuts power to the coach for around 15 seconds, then closes again supplying power for 15 seconds and then shuts the power off again.


Lots of things can be wrong here...  it would help for you to tell us the make and model of your transfer switch, and the make and model of your surge protector.

Just off the top of my head, but without sufficient information, this sounds like a voltage drop problem to me.  IOTW, when you put a load on the system, the incoming voltage drops just enough for either the ATS or the protector to drop out.  The voltage immediately goes back up, of course, leading to a repetitive cycle.

need to verify your grounds     ...  also your power supply at pole might not have proper grounding.  Just a few of the things that can go wrong.


Actually, grounding (or lack thereof) can not cause this issue.  I don't disagree that all grounds should be checked, for safety, but the ground is not part of the circuit that actuates the transfer switch.  That is operated strictly by one of the hots and the neutral.

-Sean
http://OurOdyssey.BlogSpot.com

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« Reply #6 on: July 13, 2012, 11:53:03 AM »

Just off the top of my head, but without sufficient information, this sounds like a voltage drop problem to me.  

......... <snip> ............. and later:

Actually, grounding (or lack thereof) can not cause this issue.  
-Sean
http://OurOdyssey.BlogSpot.com


I'm not presuming to argue but help me understand why a high resistance connection in the ground/neutral wouldn't contribue to a voltage drop just as surely as a high resistance in the hot?
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« Reply #7 on: July 13, 2012, 12:26:04 PM »

I believe that it may be a terminology thing. Ground and neutral are totally different, and the ground carries little if any potential, but the neutral (white wire) does carry power as one half of the completed circuit.

It is most likely something to do with voltage that is causing the operators to cycle as the load causes the voltage to drop.

To my knowledge, most transfer switches are mechanical, operated by a electrical device, like a motor, or a solenoid, and once operated, it will stay in the operated position until the control circuit gives an instruction to change.

If there is a "no voltage" sensing circuit, that will react to voltage changes and cause the system to try to switch to another power source.
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Iver
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« Reply #8 on: July 13, 2012, 02:49:06 PM »

Okay I did some further testing.
The transfer switch is an Esco.  ES50 volt transfer switch.  The other is a Leviton Transient voltage surge suppressor.  120/240 volt.  It has 2 lighted green led's.
The transfer switch does have a 105v cutout relay. It waits until the voltage from either the genset or shorepower have 105 volts and then it energizes.
The plug in my shop is 111.3 volts and inside the coach the voltage is approximately 110.6 volts.
I do have the surge suppressor box which has 2 green lights which are illuminated.
So can running one air conditioner as well as the battery charger (which is always on), drop the voltage enough to trip the transfer switch?
 
Thanks, Iver.
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Sean
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« Reply #9 on: July 13, 2012, 08:30:29 PM »

... The transfer switch does have a 105v cutout relay. ...
The plug in my shop is 111.3 volts and inside the coach the voltage is approximately 110.6 volts.
...
So can running one air conditioner as well as the battery charger (which is always on), drop the voltage enough to trip the transfer switch?


Yes, and this is my guess as to the source of your troubles.  Connect a quality voltmeter to the input of the transfer switch and monitor this while it happens -- I think you will find the voltage dropping below 105.

The fact that the shop outlet is only 111 volts to begin with suggests it's already at the end of a long run.  Add to that the run from there to the coach, and you have the recipe for voltage drop.

What gauge is your shore cord, and what gauge runs from the shop panel to the outlet?

...
Actually, grounding (or lack thereof) can not cause this issue.  
...
http://OurOdyssey.BlogSpot.com

... help me understand why a high resistance connection in the ground/neutral wouldn't contribue to a voltage drop just as surely as a high resistance in the hot?


In the neutral, yes, but the ground is not involved.  So whether the grounds are good or not should not come into play here.

Just to clarify for anyone following along:  The ATS is activate by a coil (or two coils) connected between neutral and a hot leg.  On shore power, the neutral is supplied from the shore cord -- ground and neutral are not connected internally inside the coach.  If either the hot or neutral has a problem that causes high resistance, for example oxidized terminals or a loose lug, then that can cause this symptom.  But the ground, which runs separately in the shore cable back to the shore panel, can be wide open and the transfer switch will never know it.

The reason I asked about the surge protector (and the model of ATS) is that some protective devices, including ones built into transfer switches, monitor all four shore connections and will refuse to connect if there is any problem at all, such as an open ground, or hot/neutral swap.

...
To my knowledge, most transfer switches are mechanical, operated by a electrical device, like a motor, or a solenoid, and once operated, it will stay in the operated position until the control circuit gives an instruction to change.


Actually, most transfer switches do not stay in the commanded position unless held there by a constant voltage source.  Some smaller styles use a double-throw relay, so the complete absence of power means they are connected by default to the "normally closed" position, but most larger styles use contactors, and so by default in the absence of control power they are connected to nothing.

All transfer switches have a "priority" input, meaning that one specific input will be connected when both inputs are energized.  In the case of a double-throw relay model, the priority input is the "normally open" side.

Folks with the double-throw type of switch will seldom experience the OPs problem because shore is typically connected to the non-priority (normally closed) input and thus is connected by default, even if the voltage is low.

HTH.

-Sean
http://OurOdyssey.BlogSpot.com
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Iver
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« Reply #10 on: July 13, 2012, 09:49:28 PM »

Okay, this is my update.
Pulled the coach outside, started the genset, started the A/C and it ran perfectly for more than half an hour until I turned it off.
What gauge is your shore cord, (6 gauge)        and what gauge runs from the shop panel to the outlet? (6 gauge)
     I think Sean has got it right.
Unfortunately/fortunately we live in a rural area at the end of the power grid in our area. Consequently the lower voltage.
          Thanks everyone for all the responses,
                    Iver.
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Abbotsford, British Columbia, Canada
"Life may not be the party we hoped for,
But while we are here we might as well dance".
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