AUTOMATIC LINE GENERATOR SWITCH

he probably meant that,for example for an electric motor, when you pull more current, the volage drops due to the wiring size and then the current goes higher than what the device usually would pull. and burn the device
not true for resistive devices though

DrewE wrote:

dougrainer wrote:
A common mistake people make is, they think a Breaker will trip when they overload the supply system. In effect, the current drops as the amp load increases and the Heat build up causes electronic items to then fail. The ATS can handle 30 and 50 but cannot handle any type excess amp/current problems. Doug

I am confused by this. What do you mean by "the current drops as the amp load increases"? Those are precisely opposite statements; it is akin to saying that speed decreases as mph increases.

The sole purpose of a circuit breaker or fuse is to cut the power in the event of an overload (overcurrent) situation. If it does not do that, it is dangerously defective.

Mile High wrote:

DrewE wrote:

I am confused by this. What do you mean by "the current drops as the amp load increases"? Those are precisely opposite statements; it is akin to saying that speed decreases as mph increases.

The sole purpose of a circuit breaker or fuse is to cut the power in the event of an overload (overcurrent) situation. If it does not do that, it is dangerously defective.

not necessarily. Breakers trip by thermal energy on a bimettalic strip. If heat is absorbed by other means such as too small of a gauge wire or cord, the braker never sees the heat even though it is supplying far over its rating. It's not unusual to see 30A RV outlets melt to the plug because the load is using 40-50-60 amps but the 30a cord is shedding the heat instead of the breaker seeing it.

Regardless, I still don't see where the OP did anything wrong. The transfer switch needs replaced, simple as that. They are junk anyway. Ours on our 5er was recalled twice.

I agree that the OP didn't do anything wrong.

The RV outlet and plugs get hot and melt not because there is more than 30A flowing through them, but because the contact is poor and the resistance of the connection is high and consequently there is a voltage drop and power being consumed by the contact point (power which becomes heat). If the current exceeded 30A (sufficiently and for a long enough time, based on the trip curve of the breaker), the breaker would trip; if anything, it would trip sooner if near the socket because of the heat from the socket warming it up. If there is, say, a two volt drop at 25A, that's fifty watts concentrated at the prong of the plug, and equivalent to holding a soldering iron in there indefinitely: plenty of heat to damage the plastic shells and wire insulation and so forth.

If a 30A breaker (or fuse) lets a sustained 60A load through without tripping, it is dangerously defective. (There have been a few cases of bad breaker designs that would fail and do exactly this sort of thing. Probably the best know example were the Federal Pacific Stab-Lok breakers, which have contributed to or caused not a few house fires.)

DrewE wrote:

dougrainer wrote:
A common mistake people make is, they think a Breaker will trip when they overload the supply system. In effect, the current drops as the amp load increases and the Heat build up causes electronic items to then fail. The ATS can handle 30 and 50 but cannot handle any type excess amp/current problems. Doug

I am confused by this. What do you mean by "the current drops as the amp load increases"? Those are precisely opposite statements; it is akin to saying that speed decreases as mph increases.

The sole purpose of a circuit breaker or fuse is to cut the power in the event of an overload (overcurrent) situation. If it does not do that, it is dangerously defective.

not necessarily. Breakers trip by thermal energy on a bimettalic strip. If heat is absorbed by other means such as too small of a gauge wire or cord, the braker never sees the heat even though it is supplying far over its rating. It's not unusual to see 30A RV outlets melt to the plug because the load is using 40-50-60 amps but the 30a cord is shedding the heat instead of the breaker seeing it.

Regardless, I still don't see where the OP did anything wrong. The transfer switch needs replaced, simple as that. They are junk anyway. Ours on our 5er was recalled twice.

example
if you have a loose dirty faulty shore power connection
it heats up
as it heats up the resistance at that point goes up
current in the circuit actually goes down, current is work, current is the 'load' on the circuit

dougrainer wrote:
A common mistake people make is, they think a Breaker will trip when they overload the supply system. In effect, the current drops as the amp load increases and the Heat build up causes electronic items to then fail. The ATS can handle 30 and 50 but cannot handle any type excess amp/current problems. Doug

I am confused by this. What do you mean by "the current drops as the amp load increases"? Those are precisely opposite statements; it is akin to saying that speed decreases as mph increases.

The sole purpose of a circuit breaker or fuse is to cut the power in the event of an overload (overcurrent) situation. If it does not do that, it is dangerously defective.

Dutch_12078 wrote:

dougrainer wrote:

Mandalay Parr wrote:

KD4UPL wrote:
I totally disagree that plugging into a 20A outlet destroyed your transfer switch.

I agree.

Plugging in did NOT destroy the box. Using a 20 amp supply when the poster was using MORE amps than supply destroyed the box. The heat build up and the drop in 120 current supply combined to destroy the box electronics. I should have clarified my first post. Doug

Something doesn't compute... The OP first said he "plugged the (toaster) oven into a 20 amp socket on the post that still had power.", and then said he started the generator while still plugged in to the 20 amp source to use the microwave. If the toaster oven was plugged in independently of the RV wiring, it would have had no effect on the transfer switch. Even if the RV power was plugged into a 20 amp source, the ATS still should have handled it since it is rated for 30 or 50 amps, and typically would default to the generator power when it started. If anything he did drew more than 20 amps from the shorepower post, the breaker at the post should have tripped. What am I missing?

A common mistake people make is, they think a Breaker will trip when they overload the supply system. In effect, the current drops as the amp load increases and the Heat build up causes electronic items to then fail. The ATS can handle 30 and 50 but cannot handle any type excess amp/current problems. Doug

What I thought he said is/was

RV plugged into shore post,
Lost power while cooking dinner

Got out extension cord and plugged into 20 amp to provide power for oven only

Decided to use MW , and started generator, transfer switch hums does not pull in

If I understood this correctly
Then yes transfer switch failed while cooking dinner
And it ha nothing to do with the 20 amp outlet

He lost power originally, because of switch failure
Then could not use generator because of same switch not working

His mistake was in not checking shore power and realizing, that he has an RV problem, not a shore power. Problem

Of course if I misunderstood what he was trying to say, it's all moot

But either way the end result is the same, he needs to replace the transfer switch

dougrainer wrote:

Mandalay Parr wrote:

KD4UPL wrote:
I totally disagree that plugging into a 20A outlet destroyed your transfer switch.

I agree.

Plugging in did NOT destroy the box. Using a 20 amp supply when the poster was using MORE amps than supply destroyed the box. The heat build up and the drop in 120 current supply combined to destroy the box electronics. I should have clarified my first post. Doug

Something doesn't compute... The OP first said he "plugged the (toaster) oven into a 20 amp socket on the post that still had power.", and then said he started the generator while still plugged in to the 20 amp source to use the microwave. If the toaster oven was plugged in independently of the RV wiring, it would have had no effect on the transfer switch. Even if the RV power was plugged into a 20 amp source, the ATS still should have handled it since it is rated for 30 or 50 amps, and typically would default to the generator power when it started. If anything he did drew more than 20 amps from the shorepower post, the breaker at the post should have tripped. What am I missing?

Mandalay Parr wrote:

KD4UPL wrote:
I totally disagree that plugging into a 20A outlet destroyed your transfer switch.
Even so, you may need to replace the switch. I once had a 50 amp ATS made by Power Max go bad. Same problem, the contactor coils wouldn't pull the switch, they just hummed. This particular unit used DC coils so that when engaged they wouldn't hum. The rectifier circuit in the switch was only delivering about 70 volts DC instead of the 100 volts the coils required. The manufacturer couldn't provide a replacement. The switch was fairly inexpensive so it was just replaced.
Have you measured the voltage going to your coils? Does it meet the specification they require?

I agree.

Plugging in did NOT destroy the box. Using a 20 amp supply when the poster was using MORE amps than supply destroyed the box. The heat build up and the drop in 120 current supply combined to destroy the box electronics. I should have clarified my first post. Doug

double post, Sorry.