Failed Transfer Switch

[lanerd]

Recently, with my MH winterized in my rv garage and connected to 30 amps through a Surge Guard model 34850 and a 30 amp dog bone, my transfer switch failed and over a period of a couple of weeks, drained my 6 6v Interstate batteries to almost 0. I replaced the batteries and purchased a new transfer switch and had it installed. All is working fine now.

However, what would cause my original transfer switch to fail....and only the shore power relay as the generator relay was fine?

Any and all info would be greatly appreciated.

Ron

[lanerd]

brulaz wrote:

lanerd wrote:
Recently, with my MH winterized in my rv garage and connected to 30 amps through a Surge Guard model 34850 and a 30 amp dog bone, my transfer switch failed and over a period of a couple of weeks, drained my 6 6v Interstate batteries to almost 0.
...

So when the transfer switch failed, your inverter took over supplying 120VAC to ?

I'm surprised that in storage you had any 120VAC loads and/or the inverter turned on. Maybe it's a motorhome thing?

Or perhaps a 120VAC heater for winter storage?

On mine, I disconnect all loads (AC *and* DC) when put into storage, and just leave the solar to replenish the batt's self-discharge.

At the very least I would not leave the inverter on.

Yeah, you got me here. Prior to this happening, I had exercised my generator by running it with two of my three heat pumps for loads. Upon completion of this exercise, I turned off the generator, but my haste I failed to switch the thermostats to "OFF". So when the generator shut down, the transfer switch defaulted back to shore power and with two heat pumps restarting at the same time (the surge guard has a 30 sec delay), i suspect the transfer switch relay for the shore power couldn't handle the amperage load and failed and then when the system defaulted to inverter, the batteries were drained.

If this is indeed the cause of the failed relay, why didn't the main circuit breaker shut down when more than 30 amps was being drawn by the two heat pumps?

[lanerd]

time2roll wrote:
Odd to fail just sitting in storage idling on utility power.
Could be any number of things. Best to inspect for heat damage to find the issue. Could also be poor installation or latent defect.
If you did something wrong your mechanic should have told you.

As I mentioned to Brett, no visual damage from my inspection. I do "suspect" the latent defect would be the culprit.

Mechanic????

[lanerd]

Another kind has different contractors (relays) for Shore and Generator.. I'm nto sure but I think these "Default" to inverter when no other power is present (That is the De-energized state of the contractors) When you plug in one set pulls in for SHORE power.. Fire up the generator and that set drops out and another set pulls in for GENERATOR.. Shut down and it drops back to INVERTER.

On this type be you on shore or Generator one set of relays is always energized.. and thus, a coil can burn out and dump you. Or a "Control" part.

John, this is the type I have and I'm sure you're correct in that when the shore power relay quit on me and the generator wasn't running (I've never set up the auto start feature), the unit defaulted to the inverter which in turn drained my batteries over time.

Ron

[lanerd]

wolfe10 wrote:
Ron,

I suspect that you will be in a better position to determine the cause of the failure by visually inspecting it. Could it have been a mechanical failure? Sure, but less likely than a poor connection.

#1 suspect is that one of the lugs securing a wire was loose, causing resistance, causing heat, degrading the wire, causing more resistance............

Did any of the wires look like the insulation was overheated? Any of the copper wire not shiny copper?

Brett.. I did inspect visually several times. I found no obvious loose wires or discoloring of insulation or wiring. The generator's relay in the switch worked just fine.

Ron

[RJsfishin]

My transfer switch is just 1 relay.
It defaults to the generator side.
If it fails,.....doesn't switch to the shore power side when plugged in,
there is no ac power to the converter, (unless gen is running) and will of course run the batteries dead.
Why did it fail, ???? Same reason that all other electric things fail ?? They are not made perfectly.
Isn't this why you should always have a good digital readout volt meter in plain sight, showing 13.8 to 14+ volts as soon as you plug it the shore power. This would probably have saved your batteries

[brulaz]

lanerd wrote:
Recently, with my MH winterized in my rv garage and connected to 30 amps through a Surge Guard model 34850 and a 30 amp dog bone, my transfer switch failed and over a period of a couple of weeks, drained my 6 6v Interstate batteries to almost 0.
...

So when the transfer switch failed, your inverter took over supplying 120VAC to ?

I'm surprised that in storage you had any 120VAC loads and/or the inverter turned on. Maybe it's a motorhome thing?

Or perhaps a 120VAC heater for winter storage?

On mine, I disconnect all loads (AC *and* DC) when put into storage, and just leave the solar to replenish the batt's self-discharge.

At the very least I would not leave the inverter on.

[byronlj]

Transfer switches are more extensive than just pairs of contacts. If a circuit board fails, it is unlikely you will troubleshoot it with a visual inspection. Mine failed in the truck camper just because the circuit delay board needed re-capped; an obvious replacement instead of repair for cost. Circuit boards can fail from time or exposure to harsh elements.
Dave

[time2roll]

Odd to fail just sitting in storage idling on utility power.
Could be any number of things. Best to inspect for heat damage to find the issue. Could also be poor installation or latent defect.
If you did something wrong your mechanic should have told you.

[wa8yxm]

What would cause the Transfer switch to fail?

I hate to get all "Religious" on you but.. Anything made by man can fail.. Just because it fails.

There are 2 or 3 kinds of transfer switch.. One (My Intelletec) when the generator is running, the contractors are NOT energized, they "Default" to SHORE power. This kind almost never fails when running on shore power.. It can (And mine did) fail when transferring (under warranty thankfully)

Another kind has different contractors (relays) for Shore and Generator.. I'm nto sure but I think these "Default" to inverter when no other power is present (That is the De-energized state of the contractors) When you plug in one set pulls in for SHORE power.. Fire up the generator and that set drops out and another set pulls in for GENERATOR.. Shut down and it drops back to INVERTER.

On this type be you on shore or Generator one set of relays is always energized.. and thus, a coil can burn out and dump you. Or a "Control" part.

Oh, the Religious part.. The Religious believe that works of God are foolproof.. That's why so many try to make fools of themselves. (Joking)

[wolfe10]

Ron,

I suspect that you will be in a better position to determine the cause of the failure by visually inspecting it. Could it have been a mechanical failure? Sure, but less likely than a poor connection.

#1 suspect is that one of the lugs securing a wire was loose, causing resistance, causing heat, degrading the wire, causing more resistance............

Did any of the wires look like the insulation was overheated? Any of the copper wire not shiny copper?