Re: Generac Generator Blues
Are you saying that the motor runs and then because it is showing no voltage that the motor shuts down? Does it have a low voltage shutoff?
As I do not know the model number and such I'll just volunteer some general information. If it is not a low oil shutoff and possibly shuts down because there is no voltage then it may not be showing voltage because the generator needs to be re-excited.
Does this generator have brushes or not in the generation side? If it is brushless, I'm not an expert, but think you will find brushless generators have permanent magnet armatures and do not need to be excited to get them to work. You may have another problem as mentioned by others above.
For generators that have electromagnetic armatures there need to be a some residual magnetism in them to be self starting. If used on a regular basis there should be no problem but if sitting for a time the armature will need some assist by passing some current through it to impart some residual magnetism. The residual magnatism will help the generator start generating power when turned and will come up to operating voltage and then be self regulating for output voltage. So, if not brushless then you may need to field flash it or re-excite it. There are several ways to do this but I'll mention an easy one here.
Field Flashing of Portable Generators
This tip comes from the Briggs & Stratton Customer Education Department. As an alternative to flashing a rotor winding with a battery applied to the brushes, an electric drill may be used. Follow these steps to flash the generator:
* Plug the electric drill into the generator receptacle.
* If the drill is reversible, move the direction switch to the forward position.
* Start the generator
* While depressing the trigger on the drill, spin the drill chuck in reverse direction. This will excite the field and the generator will now produce electricity. If spinning the chuck one direction does not work, try spinning the chuck in the other direction as you may have the reverse switch positioned backwards.
Use caution not to get your hand or other materials caught in the chuck. As soon as the field is excited, the generator will produce power and the drill will turn on.
The reason this works is because the electric motor in the drill will act as a small generator when spun backwards. The magnets in the drill's motor induce a voltage into the motor windings, which is fed back through the trigger, cord and into the generators receptacle. From there it goes into the power winding of the stator. The voltage going through the power winding creates a magnetic field, which is intensified due to the iron core of the stator laminations. The rotor intersects this magnetic field as it is spun past the power winding, thus inducing a voltage in the rotor winding. Once current flow is present in the rotor winding the rotor has been flashed.
If flashing the field does not make the generator work, you may have additional problems, besides a lack of magnetism in the rotor. As I am not sure if this applies to your particular generator further testing may be needed. Hopefully, this will give a simple way to field flash your generator if needed. I realize that yours at 25KW may not be considered protable at least it is something to consider. Or maybe someone else can use this.
