Preventive Maintenance Auto Transfer Switch

MrWizard wrote:

The transfer switch is rated to function with heavy loads (such as air conditioner) being active when engaged if you have auto temp start for the generator. Many of us have animals and keep the temp start active when there's a chance of hot weather driving up inside temps.

i disagree with the way you 'think' it functions

the stat clicks on calling for power
the ems auto starts the genset
after the warmup delay the transfer switch closes
then the ems allows power to the A/C

the power surge goes thru 'closed contacts' of the transfer switch

IF the A/C was pre-engaged and the contacts closed, there would be a tremendous arc from the compressor 'star up spike load' up to 10x what the run current is, that could be 120amps or more arc on the contacts

True, .. I was attempting to describe why the IOTA transfer switches have been recalled without getting into the detailed mechanics of how the switch works for loads such as air conditioners. Other loads such as Hot water, sound systems, space heaters, etc are present when the switch makes contact. It's those loads that are heavy enough to drive the EMS nuts if the connection is loose in the transfer switch. Bottom line, .. with the delay they are designed to work with AC's in the 'ON' position at startup. Virtually every Monaco coach wired for 50 amp - built from 2004 - 2009 has the recalled IOTA transfer switch installed as OEM.

IOTA closed it's doors after the recall, and of course Monaco is not held accountable under the (then) new ownership of Navistar for those build years. So the followup is at the discretion of the coach owner, ... I have never been notified of the recall, but found out instead through publications such as Motorhome magazine. Pretty sad really ...

I fought the same problem as the OP until I read the recall notice and looked inside the transfer switch ... not a pretty sight and burned badly. The relay contacts where fine, but the feed wire connection was badly burned.

His may be another situation, but there's no harm in looking, especially if his is one of the faulty, fire prone recalled units.

Corkey05 wrote:
If your 07 is like my 08, the IOTA transfer switch has been recalled by NTSA. The terminals loosen up over time and act just as you describe plus they can overheat to the point of causing a fire.

Info ....

The transfer switch is rated to function with heavy loads (such as air conditioner) being active when engaged if you have auto temp start for the generator. Many of us have animals and keep the temp start active when there's a chance of hot weather driving up inside temps.

When my transfer switch first acted up, the control panel lights would come on one at a time as you say, then shut off and restart. It was the transfer switch kicking out from a damaged (loose and overheated) terminal on L2.

You can tighten the terminals inside the transfer switch and it will work again for a while, if it's not already damaged like mine was. But the condition usually returns, ... best to replace it.

Don't these idiot manufacturers know what a SEMS SCREW IS?

With really critical tab connections I use a longer SEMS screw to bind the wire terminal to the threaded tab then use a KEPS NUT on the other side, I freakin' guarantee you that termination will not "loosen up" EVER.

Any six year old mechanical transfer switch should have its load contacts visually checked about every 2 or 3 years. If pitted, use a very fine file or fine sandpaper (NOT emery paper) to smooth the contact points. Other than that, tighten wiring connections and enjoy.

The 70 amp switch in my coach is twice oversize for the 30 amp generator so I don't worry too much about overload on the contacts. The 200 amp switch on my whole house generator is a bit oversize for the 83 amp generator. No trouble from either switch since new.

(Another chief, 54200, 57-87)

JimL

The transfer switch is rated to function with heavy loads (such as air conditioner) being active when engaged if you have auto temp start for the generator. Many of us have animals and keep the temp start active when there's a chance of hot weather driving up inside temps.

i disagree with the way you 'think' it functions

the stat clicks on calling for power
the ems auto starts the genset
after the warmup delay the transfer switch closes
then the ems allows power to the A/C

the power surge goes thru 'closed contacts' of the transfer switch

IF the A/C was pre-engaged and the contacts closed, there would be a tremendous arc from the compressor 'star up spike load' up to 10x what the run current is, that could be 120amps or more arc on the contacts

If your 07 is like my 08, the IOTA transfer switch has been recalled by NTSA. The terminals loosen up over time and act just as you describe plus they can overheat to the point of causing a fire.

Info ....

The transfer switch is rated to function with heavy loads (such as air conditioner) being active when engaged if you have auto temp start for the generator. Many of us have animals and keep the temp start active when there's a chance of hot weather driving up inside temps.

When my transfer switch first acted up, the control panel lights would come on one at a time as you say, then shut off and restart. It was the transfer switch kicking out from a damaged (loose and overheated) terminal on L2.

You can tighten the terminals inside the transfer switch and it will work again for a while, if it's not already damaged like mine was. But the condition usually returns, ... best to replace it.

It wasn't excessive or low voltage, at least not per the Progressive Industries displayed readings. I can't quote the exact readings to you since I didn't write them down but both lines read E-0 for no errors detected.

MrWizard wrote:
clean dry, never switch with a heavy load on like A/C

i think very likely it was the progressive surge protector not letting power thru
voltage either too high or to low

next time this happens, get your digital meter out and check the voltage at the pedistel

X2

Voltage at the post was probably just below minimums due to excessive draw from other campers. Your transfer switch probably has a function where it will ignore input where the voltage is too low. That protects your appliances from damage.

clean dry, never switch with a heavy load on like A/C

i think very likely it was the progressive surge protector not letting power thru
voltage either too high or to low

next time this happens, get your digital meter out and check the voltage at the pedistel