Electrical Question For the Brain Trust
 

For years when the power went out we had an old Coleman generator which would supply enough juice to run our fridge and freezer or other small appliances as needed. A few years ago, we upgraded to a larger generator which is wired in through a breaker panel. It handles the essential loads such as water heater,lights, pump and about half of the electrical outlets . It is a great bit of peace of mind, as we can live almost normally if there are major power outages.
There is one issue, however: the freezer doesn't like the generator supply. It will beep periodically, try to start and usually shut down within a second. Also, our washing machine won't complete a cycle if powered by the generator.
I have a theory the old generator (30 years old) produced a natural sine wave which the electronic brains of the freezer and washing machine needed, but the electrical output of the new generator is a "squared off wave" which doesn't seem to bother our fridge or even our computer but upsets the control modules of two appliances.
Might my theory be valid? If so, is there a cure, aside from changing the generator or the freezer and washing machine?
Any advice or suggestions appreciated.
Best
Les

You know those old computer backup power supplies. They had a battery and electronics that turned the DC power into AC with "power conditioner" quality type sine waves. You could buy an cheap old one with a stuffed battery as that part isn't needed and see if the power conditioner aspect of it fixes the problem. As the battery backup devices tend to be small you would hook it in just before the freezer or washing machine.

What is your new generator? A square wave is unlikely from a true AC wound generator, and even less likely from an inverter, unless it's malfunctioning.

Any of your friends own an oscilloscope?

Is it possible you are getting voltage drop when the compressor starts? A good Fluke meter will measure minimum voltage. I would do some testing with minimal load on the new genset. And some investigation into what the freezer beeping indicates.

Something is definitely wrong.

Thanks Bill. My feeble brain was casting in that direction. If it works it would be a cheap fix.

Best
Les

That would be a good test...

The generator is an 8000 watt Firman.
The electrician who tested out my concerns after the generator panel was installed reported no voltage drop on that circuit. I had initially thought about that when the problem arose but the volt are there. The problem doesn't seem to change depending upon load. Even if every other circuit is idle the freezer sounds its alarm. What is strange however, is that sometimes it will just start and run as normal for a while. Then five minutes later it will be beeping and short cycling.

Appreciate the questions and suggestions.
Les

Is the generator grounded to the electrical panel?

There's some generators that give computers fits. Normally noone advertised that they are making a nice square wave. Nature doesn't like square waves.

Could your electrician borrow an oscilloscope?

generators give off horrible power. of course it's less horrible when there's no other power but it's still horrible.

is it worth getting an avr? or a small invertor gen just for the fridge? laundry can wait. milk otoh...

You know it's kind of funny. In the two years after we installed the generator and panel ( oh yes, everything is to code, otherwise the inspector from the power company would not allow us to re-connect), we had no power failures. Eventually I sold our old generator. The 30 year old unit which the freezer liked.:rolleyes:
Today I will look for a computer backup power supply and see if that addresses the problem.
Thanks all.
Les

Did you try contacting Firman and tell them the problem? An analog voltmeter might be quick enough to detect any changes in voltage.

The generator inverter is a reverse pulse width modulator (PWM) that takes flat line DC and creates and filters the sine wave created as best as its designed to do.
One trick is to install an isolation transformer on the Gen output between your panel input.
I found that throwing copper in front of dirty power helps transient sensitive devices.
Please operate on your Generator in a stand alone fashion isolated with a locked out EXO from the grid. This keeps you from killing the guys who help pay one of my pensions

No worries, Ted. Installation includes a lock out panel which is either line or generator.
I tried routing the freezer supply through a surge protector/ back up supply with no change in operation.
Next step is to get the electrician in.
Thanks Guys for all the suggestions and help.
Best
Les