Your last generator Maintenance Run

[Chilliwack Murray]

Most generators with automatic voltage regulators will reduce voltage if the frequency drops below about 59hz which effectively reduces kw load (amps x volts) to allow the engine to catch up however if the load is too much for the engine you end up running with lower voltage. Simpler transformer regulated units also drop voltage with rpm but it’s not by design as much as physics.

A standard motor will draw more current as voltage decreases and cause overheating and is the main reason motors fail. Higher voltage and frequency changes are actually not that harmful to a motor.

An electronic drive like a VFD takes the supply voltage, rectifies if then inverts it back to AC again so the motor never sees the generator frequency or voltage. Most VFDs are designed to run on 50 or 60Hz system last so they are very tolerant of a slow running 60Hz unit.

Not surprising they see a lot of failures of standard motors when people just add load until the gen just won’t take any more.

The frequency based load shed switches are effective in preventing a complete failure but under frequency is a measure of last resort when it comes to load management. A load shed output that is triggered at 90 - 95% is a much better way to control load but you get what you pay for.

 

[nikdfish]

Storms rolled through last night & did a number on a bunch of power lines. Our neighborhood's power dropped about 9:20PM (tree damage), the 22KW whole house kicked in as designed, so we pretty much ignored it & went to bed. Power was restored around 4:30 AM (the time stamp on the text message on my phone telling me the generator was ready to run, is how I know when power was restored).

It was nice not to have to get out in the wind & rain to mess with fueling, connecting/disconnecting a portable or worry about whether food in the fridge & freezer was going to be OK until power came back.

 

[Industrial Toys]

I have never seen a generator AVR that looks at frequency. Not a typical Diesel generator anyway. They (like a Basler AVR) look at output voltage and adjust Field voltage accordingly. You can get an electronic Governor (like from Governors of America) that goes on the Injector pump and controls speed by frequency, which is really nice, but in truth not often required. The benefit of that is also that you can start the generator slower for warmup, now that you are controlling the throttle, which IS NICE!

I was thinking about those frequency driven load shed devices. I am still playing with my most recent project, the Cummins Onan, Quit Diesel Inverter 7.5 set. I guess that system would be quit useless on this set.

 

[Chilliwack Murray]

Anything not consumer oriented has had that for decades and even a lot of consumer product now have that feature.

Its called under frequency roll off (UFRO) or V/Hz and has an adjustable knee point and roll off rate on a better regulator.

On your last point about running a generator slower for warmup, without the under frequency roll off function you will burn out your regulator and/ or field windings as the reg will still try to produce rated voltage at idle.

 

[Industrial Toys]

Maybe I only deal with stuff decades old. To me, the ideal is to have frequency control throttle electronically (precisely) and output voltage controlling field voltage.

Except for this new test project, (The QD) I really don't like computer controlled generators. One less (BIG) thing that I can work around in a failure. If I had a failed VR I could grab another generic one, or use a variable PSU to feed the field if I had to, and loads were fairly constant.

 

[Chilliwack Murray]

Agree on the simple stuff... Lots of ways to skin a cat on a simple unit but when one ECM starts and runs the engine, controls governing, voltage regulation and protection you it’s pretty tough to rig something up in a pinch.

 

[Industrial Toys]

It would leave Magiver, scratching his head for sure.

Nothing is as it was before, not even a little while. Every "same" model of electronic something, will be different than the one you got only six months ago. Makes it virtually imposible for the little guy who only sees a few to keep up.

 

[HarryVanderpool]

Storms rolled through last night & did a number on a bunch of power lines. Our neighborhood's power dropped about 9:20PM (tree damage), the 22KW whole house kicked in as designed, so we pretty much ignored it & went to bed. Power was restored around 4:30 AM (the time stamp on the text message on my phone telling me the generator was ready to run, is how I know when power was restored).

It was nice not to have to get out in the wind & rain to mess with fueling, connecting/disconnecting a portable or worry about whether food in the fridge & freezer was going to be OK until power came back.

The fridge and freezer would have been fine until the am.
We would not have started our generator until morning.
And, since power was restored at 4:30am; we wouldn't have started it at all.
There are many good reasons for automatic generators, just none that apply to us.
Our approach is to run generators as little as possible, but definitely as needed.

 

[Sawyer Rob]

The fridge and freezer would have been fine until the am.
We would not have started our generator until morning.
And, since power was restored at 4:30am; we wouldn't have started it at all.
There are many good reasons for automatic generators, just none that apply to us.
Our approach is to run generators as little as possible, but definitely as needed.

We are the same way... Why waste money on fuel if you don't need to!

SR

 

[Looking4new]

I didn't need a maintenance run, the power went out at 4:15 this morning and the genny ran from 7 until 1 P.M. when the grid came back on.
I am glad I have wood heat. The overnight temp was around 26°F.