Your last generator Maintenance Run

[grsthegreat]

Generac supposedly has an instrumentation board and app (Mobile link) that sends gen set operating parameter data to you over WiFi.

Supposedly you can use it to retrofit older generators but I can’t find a retrofit install manual online and let’s just say I want proof before I jump in...

Here is what they say it will do:

View attachment 640798

The Generac unit will work on any generac air cooled or liquid cooled units 2010 model year and newer ONLY. Liquid cooled units will also need a harness extension kit. The units available for retrofit AT THIS TIME are cellular ONLY. They plan on offering a wifi option soon...but have no idea when.

 

[3930dave]

Thanks g !

Rgds, D.

 

[RjCorazza]

Yes, check 2&6. I would also check 1&4.
As I read the schematic, 2&6 are the sensing input to the AVR to tell it how many volts it's putting out.
1&4 are the AVR output to feed into the rotor (via the brushes) and control the voltage of the field that 2&6 are driven off of.

Aaron Z

Follow up...
There was a loose terminal connector from the voltage regulator going to the control board. My electrician neighbor diagnosed and repaired the generator, and got a free generator.
I am happy with my 15kw PTO generator.
Thanks for taking the time to get me in the right area!

 

[aczlan]

Follow up...
There was a loose terminal connector from the voltage regulator going to the control board. My electrician neighbor diagnosed and repaired the generator, and got a free generator.
I am happy with my 15kw PTO generator.
Thanks for taking the time to get me in the right area!

Glad to hear that's all that was wrong with it.

Aaron Z

 

[90cummins]

I have a several generators, my 25kw PTO unit uses brushes as does my Generac 4000xl.
My 5kw Master generator with a Yanmar Diesel is brushless.
From what I’ve read brushless generators produce cleaner power than brush types.
Could the resident experts elaborate on the pro’s & con’s of each?

Thanks
90cummins

 

[Chilliwack Murray]

Brush or brushless has no effect on power quality on any rotating field machine however most brush units are 3600rpm which are often lower end unit and consumer units built to meet a price point.

Power quality is a vague term and might mean voltage or frequency stability, harmonic content, or often (and incorrectly) the ability of a unit to operate with poor power factor and load induced harmonics.

3600RPM units are slightly less efficient and have some inherent weaknesses but they aren’t all that significant in most cases. They have less ability to support a low lagging (this is important for later) power factor due to the fact there is half the copper in the rotor (field) and will have greater voltage dip on transients than a 4 pole with all else equal. They also have less inertia to absorb large kW transients because the rotor and often the engine has less mass.

A cheaply made unit built with the minimum amount of copper in the stator is where you will have issues with harmonic distortion of the sine wave regardless of whether a 2 or 4 pole rotor is used. Winding pitch and skew determine the harmonic content of the sine wave. It’s a little deep for here but the farther around the barrel of the alternator each turn is wrapped, the more voltage you get from that length of copper however the field interacts with two phases of the stator at once creating distortions. 2/3 pitch is optimum for most applications but requires about 25% more copper for the same output. Skew puts one end of the windings into the field before the other also requiring slightly more length per winding.

Overvoltage due to a leading power factor load (here’s the important part) is usually blamed on the generator but is caused by the load and there is little that any generator can do to control this. Leading power factor causes a rise in voltage in a system, the avr will cut back excitation but it can’t eliminate residual magnetism in the rotor so there is always some field active. If there is insufficient resistive load to keep the voltage down, it will run away. Industrial units will have over voltage and possibly loss of field or reverse kVAR shutdown for this. This can happen anywhere past about .95 leading power factor on an 1800 or 3600 machine.

 

[Industrial Toys]

I would prefer brushed. Easy peasy to replace and not an issue for the amount of hours I put on a genny. Rather deal with easy to get at brushes than failed diodes buried in a brushless design.

My FUEL system FIASCO continues on my little 7.5 Quiet Diesel. Still sucking air and loosing prime.

 

[Chilliwack Murray]

You should never need to replace diodes on a brushless machine, they outlast the windings.

Apart from parallel units nearly every failure I’ve seen is related to loads - usually leading power factor reactive loads.

Brushes are more problematic now that field resistance is monitored by microprocessor controls. A little frost or corrosion on the slip rings and you get a shutdown or warning fault. A traditional regulator would just drive it a little harder if the output was a little low, though sparking at the brushes will take out lesser AVRs.

 

[Industrial Toys]

I have heard of Diodes failing in a brushless genny. I still rather have something I can repair in half an hour than yet another thing that can leave me out for the count.

 

[grsthegreat]

You should never need to replace diodes on a brushless machine, they outlast the windings.

Apart from parallel units nearly every failure I’ve seen is related to loads - usually leading power factor reactive loads.

Brushes are more problematic now that field resistance is monitored by microprocessor controls. A little frost or corrosion on the slip rings and you get a shutdown or warning fault. A traditional regulator would just drive it a little harder if the output was a little low, though sparking at the brushes will take out lesser AVRs.

ya, Generac has updated software to allow for 60 seconds run time before checking output to address ice on slip rings/brushes. seems to have stopped wintertime faults on air cooled. i have never had to replace brushes in a unit...but i have 6 sets on hand. simple to replace. I did sell one set to someone that needed to replace theirs. they did work themselves.