Bad transfer switch?

[David T. Richelderfer]

The symptoms:

1. When on the Onan Quiet Diesel generator power, both legs are showing good voltage on the Aladdin.... about 120v on both legs.  The inverter works normally with both battery banks, both house and chassis banks, getting charged/maintained.

2. When plugged into either 50 amp or 30 amp shore power on separate breakers, LEG1 is showing good voltage, LEG2 is showing OFF.  LEG2 must be the leg that feeds the inverter because on the inverter's remote panel there is no "AC IN" light and the batteries are not being charged/maintained.  The house battery bank loses charge over time.

3. This symptom with LEG2 showing OFF on the Aladdin has happened a few times in the past week or so.  The Aladdin's LEG2 OFF status seems to be solidly OFF now.

Logic tells me the most likely culprit is the Transfer Switch.  As far as I know, it is the original Transfer Switch.  I suppose another possibility is a loose connection where the shore power cord attaches to the coach.  The shore power cord is on an electric extend/retract mechanism so its connection point is not readily accessible.

I have done several searches here on the Forum but I am not sure which Transfer Switch model is the correct unit to replace the one in the coach.  I think the Transfer Switch needs to have the plug-in connection for the Aladdin wire to pick up the leg voltages - yes?

Thanks in advance... DTR

[Frank Bergamo]

David,

I believe generator power takes priority thru transfer switch. If it is working properly on gen power, transfer switch may not be switching back to shore power when gen is disconnected. As you stated, your power cord could also have a bad connection. Before buying a new transfer switch, I would check connections at cord reel to make sure you have proper power at both legs of cord reel. Hope this helps.

[Lee Welbanks]

David, Have you checked that you are getting all four legs from the park power, open up the transfer switch panel and meter the legs to ground, you should have 120 volt on both power legs to grd. You may have lost a power leg in your cord. Check the park power plug to be sure it is suppling power on both legs to grd and neutral.
If you have both power legs in the transfer switch, when the contactor is engaged is power coming through it to the coach, might just be a bad contactor.

[David T. Richelderfer]

I am pretty sure the problem is not at the power pedestal because this problem I have described has been happening at three places where we have been parked.  This winter, while the coach was parked in our driveway beside our house in Yuma, the inverter lost power a couple of times while plugged into our 30 amp pedestal.  On the trip back to Oregon this past week, we stayed at an RV park in Winnemucca for two nights and while there when plugged into 50 amp the problem occurred as well.  Now the problem has happened again when plugged into either 30 amp or 50 amp while parked at our house in Oregon.

After reading Frank's and Lee's replies, I think it's time to get out the multi-tester and crawl into the basement to first check the wire connections going into the transfer switch while unplugged and subsequently check the power voltages going into and coming out of the transfer switch.

I am in no hurry; I might get to it this week.  We are here for the summer.  Yesterday, I put my larger portable charger on the house battery bank so it's being maintained at 12.6v or so.  The house and yard, after being gone for 6 1/2 months, have a higher priority.

Thanks... DTR

[David T. Richelderfer]

Okay...  I took the cover off the transfer switch.  BTW, the transfer switch is an ESCO ES50M-65N.

1. The inside of the transfer switch is absolutely clean - no dust, no melted wiring, and no blackened areas on the circuit board.

2a. When plugged into 50 amp shore power on the inbound side to the shore power switch module:
    (On the Aladdin, leg1 showed 120v, leg2 showed 0v, and the inverter showed no inbound power.)
    The red wire (leg1) to the white wire (ground) had 120v.
    The black wire (leg2) to the white wire had 120v.
    The red wire to black wire had 240v.
    Both the red wire and black wire to the bare copper wire (neutral) had 120v.

2b. When plugged into 50 amp shore power on the outbound side of the switch module:
    The red wire to the white wire had 120v.
    THE BLACK WIRE TO THE WHITE WIRE HAD 0v, NOT 120v.
    THE RED WIRE TO BLACK WIRE HAD 120v, NOT 240v.
    The red wire to the bare copper wire had 120v.
    THE BLACK WIRE TO THE BARE COPPER WIRE HAD 0v, NOT 120v.
    (The lines on capital letters seem to show errors and show no power getting through on leg2.)

3. With the generator ON and after a few seconds, the transfer switch clunked, then both leg1 and leg2 on the Aladdin showed 120v, and the inverter showed inbound power and started charging the battery banks.

4a. With the generator ON, the inbound side to the generator power switch module:
    All wires showed the same voltages as in 2. above.

4b. With the generator ON, the outbound side to the generator power switch module:
    All wires showed the same voltages as in 2a. and 4a. above.

Now for the kicker...

5. The generator was turned OFF, leaving the 50 amp shore power ON and on the Aladdin both legs showed 120v with the inverter showing inbound power and charging the batteries.

5b. Now all the wires, inbound and outbound, on the shore power transfer module are showing the same voltages as in 2a. above which was on the generator transfer module.

My conclusion is the shore power switch module is intermittent at best - it wasn't correct when I first plugged into shore power but corrected itself after I shut OFF the generator.

Agree or disagree, or what else could it be?

[Eric Maclean]

David
You are correct the contacts on the bad leg are likely dirty or pitted ( burnt)
When you shut down the gen set the relay contacts dropped down well enough to make a good contact
This is a common problem sometimes if there has been a bad connection at the transfer contact they may get hot and burnt or pit the contacts or even wear!en the spring which loads the contacts when the relay pulls in.

You'll need to remove all power sources and dis assemble the relay contactor to inspect and clean the contacts
Warning don't leave it as it is because the more load you put on a weak or bad  high resistance connection the hotter it will get
( fire hazard)



Hope this helps
Eric

[David T. Richelderfer]

I was perusing the internet for a replacement switch module, GE CR353ADY39A.  There seem to be several firms that sell them priced from $65 to $135.  There is also one firm that will repair them.  I am wondering how difficult it is to change them out, and whether if I'm replacing one, then why not replace both.

What I don't understand is what the small circuit board does that lies in there beside the two modules.  The circuit board must be connected to the modules but I cannot see in there well enough to figure it out.  I am hoping I can change the switch module/s without removing the transfer switch box from the ceiling of the basement.

[Eric Maclean]

David
The circuit board contains the logic switching for the relays and provides the delay when the gen set comes onboard.

It shouldn't be that hard to replace them if you can get replacement relays
Check to see if there is a manufacturer name and model or part number on the relays maybe take a picture and post it.

Remember the alladin system current pickups won't come with a new transfer switch which might make fixing the k!d one more appealing.

[Eric Maclean]

David
This is a link to the shore power relay

https://www.ebay.com/itm/GE-CR353ADY39APAK-240-480-600-Volts-AC-L1-L2L3-T1-T2-T3-Ports-/333794195071?_ul=IN

This is a link to the gen power relay

https://www.galco.com/buy/GE-General-Electric/CR353AD3BA1

Hope this helps
Eric

[David T. Richelderfer]

Interestingly, I looked all around the transfer switch box for the Aladdin leg voltage pick-up wire connection  - never saw one.  I suppose it could be above the two large inbound wire bundles but there are no toroids in the transfer switch box either that I could see.  There is another like-sized, gray metal box right beside the transfer switch box that the wires go into from the transfer switch box.  If this other box has a label, then it's on the side up against the ceiling.  My guess is it's a built-in surge guard.  Tomorrow I'll spend some time on the internet finding one or two replacement contactor modules that are in stock and reasonably priced.  Meanwhile, both legs from shore power are working fine and only pulling 2 amps at 120v showing on the Aladdin with the battery charging on float status.

[David T. Richelderfer]

It seemed logical that the two contactor modules in the transfer switch box should be slightly different because of the origin power requirement priority.

The shore power contactor module in my transfer switch box has a part number, GE part CR353ADY39A, and is labeled T1, T2, and T3 on the inbound side with labels L1, L2, and L3 on the outbound side.

But the generator contactor module has no part number and is labeled T4, T5, and T6 on the inbound side with labels L4, L5, and L6 on the outbound side.

So, obviously, the modules are different.  Thanks for the part number for the generator contactor module because I didn't have it.

[David T. Richelderfer]

Our coach now has a new transfer switch.  It is the same model as the old transfer switch.  The first replacement transfer switch I found was quoted at about $280.  After a week or so, I decided to not change the contactor modules inside the old switch and elected to get a whole new switch but the $280 switch I found had been sold.  So the firm found another one but its cost was $351.  I believe this transfer switch is not being manufactured anymore, so my delay in ordering the $280 switch meant another switch had to be found in a supply warehouse; where it came from I have no idea.  With freight, the cost was near $400.

A friend came over today to install the new transfer switch.  Because the switch's box size was smaller, the removable hole plugs through the new box did not line up with the wiring coming from the shore and generator cords.  So, after much cogitation, we decided to take the two contactor modules and the circuit board out of the new transfer switch box and install them into the old switch box.  Had the contactors' holding bolts not exactly lined up, we would not have done this.

Anyways, after a couple of hours of work, the transfer case is effectively new... and better yet, works!  And I am pretty sure it's working properly, i.e., the generator's power to the transfer switch has priority over the shore power.  One thing that seems different is when the transfer switch switches between the two inbound power sources, it has a 10-to-20-second delay before the switch over is made.  If memory serves, the old transfer switch had no delay when making the switch over.  I know the generator has a built-in delay but I thought in the past when shutting off the generator, the switch over to shore power was immediate.

[Bill Lampkin]

David, I think, but I do not know, that the aladdin module looks at the AC power (shore power) first, so there is a delay, at least that is what happens on our coach when plugging into shore power. When switching from either gen or shore to our new inverter, the inverter switches power so fast not even the clock on the microwave gets upset! Glad you got it fixed.

[Bill Lampkin]

Did your post-mortem determine the actual failure? Was it a contact that burned up? Other than that or a burned out coil, there is not much that can go wrong with a transfer switch. Most problems are related to loose terminal screws and resulting overheated wires.

[David T. Richelderfer]

Yesterday, I did not take, nor have the time to check the internals of the two contactor modules.  But I do plan to take a peek in the coming days.