"Dirty" Generator Power results in furnace premature failure.

[Cabinetman]

Hi all.

I just had to replace the transformer on my Becket oil burner. I had replace it once before about 2 years ago but it has provided perfect service for over 10 years before that. So, what made it fail?

When my buddy, who is also my hvac guy, stopped by with a replacement, he asked me if I had run my furnace on my generator. I had but I have a nice unit properly wired into my home. He said that the power being generated by the generator was 'dirty' and was causing premature failure of transformers. He said he'd replaced a case of them already over the past few months. It does take a while for the damage to show up but it does eventually with the transformer finally failing and no spark being generated.

So, a word to the wise. Grab a replacement transformer and have it on hand should your old one fail on you. It's a very straight forward job only dealing with two wires. Piece of cake, actually.

Rome

 

[Gator9329]

I wonder if there is a filter or line conditioner that would help solve this?

 

[snitm]

I have my generator hooked up to an APC Universal Transfer Switch (UTS10BI): APC Universal Transfer Switch 10-Circuit 120/240V
It has the ability to designate certain circuits as "Uninterruptible" which means they are first powered by the fairly substantial APC batteries that are also connected to the APC Universal Transfer Switch. I couldn't be happier with my setup but I also haven't had to operate on generator power for a sustained amount of time (only tested it for a few hours). But I do like the fact that my boiler isn't directly connected to the generator power (that batteries act as a buffer that provide clean power).

 

[drgrant]

I wonder if there is a filter or line conditioner that would help solve this?

It usually costs electricity to turn shit power into good. It's easier and cheaper to just not generate shit.

-Mike

 

[appraiser]

A transformer? all that is is a magnet and some wire.

Were there electrical components associated with it? Now it is a power supply.

I can see components getting fried, but it takes a whole lot of wrong to fry a transformer

 

[joe847]

I can see components getting fried, but it takes a whole lot of wrong to fry a transformer

BINGO!

I have conservatively installed or replaced over 5000 transformers in my career. I have never seen one go bad that could be attributed to "dirty power". The usual culprits are age or a very large or prolonged voltage spike.

Transformers are one of the simplest pieces of equipment around. They run until the insulation on the windings is gone.

 

[Chet0729]

A transformer? all that is is a magnet and some wire.

Were there electrical components associated with it? Now it is a power supply.

I can see components getting fried, but it takes a whole lot of wrong to fry a transformer

I was thinking the same thing. Dont see how dirty power could affect a coil. If anything the coil will make power dirty when it energizes and deenergizes.

 

[KenK]

Well Got to chime in.
Seems to me any transformer would filter out any "dirty" power ???(I am assuming harmonics) sign wave noise???
Then again I know some of the German furnaces have electronic controls that do not like the older mechanical governors. They won't even run.
The larger APC units do not like generator power either. They will look at the frequency the shut back off. But there is a fix for that too...

I was thinking the same thing. Dont see how dirty power could affect a coil. If anything the coil will make power dirty when it energizes and deenergizes.

 

[Cabinetman]

He said that the manufacturers indicated that the sine wave was not the same between the generator and the power company. Regarding that, what else could fail the transformer? It's like a big coil, right? Transforms line voltage to high voltage at low amps to bridge the gap at the two electrodes over the nozzle. Something wore it out prematurely. I'd like like to say that this guy knows his stuff but if you have a better explaination I'd love to hear it so I can share it with him. I'd also remind you that he said he's been replacing them like mad, well over the normal number of units.

Rome

 

[jackal134]

he's right , plus the new becket transformers are not the same as the old style. The old put out 10 kv vs 15 kv for the new style. The new ones are more electronic based and are a lot more susceptible to a bad sine wave just like anything electronic, only thing is they aren't smart and don't have any filters in them.

 

[Cabinetman]

Thanks for that info. I'm going to have two on hand just in case since I anticipate having to run my furnace on my generator a bit more in the near future.

Rome

 

[MisterHappy]

Here's an interesting thing that might cause trouble:

Back when Irene came through, we lost power, as a lot of folks did. House was quieter than usual.

My thermostat, which is battery powered, apparently called for heat.

My older forced hot air system has a millivolt control system which means that the pilot light acts upon a thermocouple to run the gas valve.

I heard the system "heating up" - though the blower system was unpowered. Now, I quickly turned off the thermostat, which shut stuff down, but I was wondering if it would have got too hot if left alone....gotta ask the gas man one of these days.

 

[Chet0729]

He said that the manufacturers indicated that the sine wave was not the same between the generator and the power company. Regarding that, what else could fail the transformer? It's like a big coil, right? Transforms line voltage to high voltage at low amps to bridge the gap at the two electrodes over the nozzle. Something wore it out prematurely. I'd like like to say that this guy knows his stuff but if you have a better explaination I'd love to hear it so I can share it with him. I'd also remind you that he said he's been replacing them like mad, well over the normal number of units.

Rome

Low voltage will cause the current to rise and can burn passive components.

 

[Finalygotabeltfed]

A transformer can't tell the difference between a square wave or a perfect sinewave, somebody is bullshitting someone here.

 

[Cabinetman]

Hmmmmmm......let me check my shoes. Nope, no BS here but only what I've been told.

AGain, however, I'll ask this. If the transformer is so simple a component, what will make them fail? Is it possible that the power from the generator is differet enough that the components do wear out prematurely?

 

[Kevin_NH]

AGain, however, I'll ask this. If the transformer is so simple a component, what will make them fail?

Corrosion (usually due to moisture), heat (especially when due to a short circuit) and voltage spikes shorten the lifespan of a transformer.

Is it possible that the power from the generator is different enough that the components do wear out prematurely?

Depends on the generator. I'd also wonder about spikes and power quality in the minutes just before the utility power goes out entirely. Newer furnaces replace the old heavy "ignition transformers" with an "electronic igniter", more advanced but more sensitive.

 

[BenDover]

There are 2 kinds of generators inverter and not. Your typical 5000w big box store (220v center taped for 2 110v circuits) unit does not have an inverter. It uses a generator head that produces a true sine wave.

A inverter generator has a generator head that powers an inverter which gives you AC.....these are typically a single 110/120v output. The good ones (Honda EU series) are true sine wave output...other brands may not be.

There are a couple ways you can stress electrical equipment with a non-inverter type generator. First the output frequency and voltage depend on the engine running at a precise speed. If a large load starts and bogs the engine for a second the power goes out of spec for that brief instant. Another thing that could happen is unbalanced loads might cause one leg to run at a higher voltage (I honestly doubt it would be greater than 5-10% but most of these things are Chinese POS so you never know). Your engine speed might be set incorrectly which would cause an incorrect frequency.

A good way to clean up AC power is a Sola transformer Sola/Hevi-Duty Products | Sola CSV Hardwired Series Power Conditioners. It's a ferroresonant transformer design that fixes voltage sags, surges, etc. Some models will also step up 120 VAC to 240 if you have an inverter generator and want to power a well pump.

I doubt that a generator would be responsible for damaging the HV transformer in a furnace if its a plain old coil style. If its a newer electronic style, you don't know what corners were cut to shave out a few pennies of profit.

 

[icyclefar]

Here's an interesting thing that might cause trouble:

Back when Irene came through, we lost power, as a lot of folks did. House was quieter than usual.

My thermostat, which is battery powered, apparently called for heat.

My older forced hot air system has a millivolt control system which means that the pilot light acts upon a thermocouple to run the gas valve.

I heard the system "heating up" - though the blower system was unpowered. Now, I quickly turned off the thermostat, which shut stuff down, but I was wondering if it would have got too hot if left alone....gotta ask the gas man one of these days.

You have built in protection for High Heat, the burner would have shut down when the high limit was reached, and probably repeated the cycle once it cooled down if the thermostat kept calling for heat.

 

[freedom2012]

he's right , plus the new becket transformers are not the same as the old style. The old put out 10 kv vs 15 kv for the new style. The new ones are more electronic based and are a lot more susceptible to a bad sine wave just like anything electronic, only thing is they aren't smart and don't have any filters in them.

this.