Operating & Installation Manual for the GSC300 Engine Controller
21
TECHNICAL NOTES ON FREQUENTLY ASKED QUESTIONS
1. Controller Memory Clear Time
The GSC300 needs 10 seconds for its memory to clear. When the power to the controller is turned off and then back on
again without waiting a few seconds to clear the memory, a loss of speed will be indicated by the GSC300 because the
controller remains in run mode and senses that the generator has stopped. This would be indicated by a Flashing
Overspeed LED. By leaving the GSC300 OFF for 10 seconds before it is returned to the Auto setting the memory will be
cleared and it will function as intended.
2. Step-Down Transformer Use On Speed Sensing Cable With Inverter Systems
In some applications engine controllers are used on generators where there is no utility connection and inverters are used
to provide AC power instead of a utility. Inverters can produce harmonics that can cause small AC signals to appear on
wires that are near any power lines being fed by the inverter. If the generator output wires are located close to a line being
powered by an inverter, a small AC signal can appear on the generator output lines when the inverter is on. This signal
can cause the engine controller to react as if the generator is running if the speed sensing wires are connected to the
generator output lines. This small AC signal can cause the controller to appear to have a Low Oil Failure when the remote
start contacts are closed or the controller is put in the manual/test mode. The controller may think the generator is already
running and immediately check to make sure there is oil pressure. Since the engine really hasn’t started yet, there is no oil
pressure and the controller sees a low oil fault. This is seen as the Oil LED turning on solid even before the engine starts
to engage the starter.
Without this false speed signal the controller will not look for oil pressure until the engine has started to run and the crank
disengages if oil verification is disabled. Simply installing a small transformer between the generator output and the
speed sensing terminals on the controller can eliminate this false speed signal. This transformer should be rated for 120 or
240 volts on the input or primary coil (depending on the generator output voltage you are using for speed sensing), and
have an output voltage of around 12VAC on the secondary of the transformer. The two wires from the secondary of the
transformer are connected to the two wires of the speed sensing terminals on the GSC300 controller. The step-down
transformer acts to reduce the false speed signal on the line to a level that the engine controller will not recognize as the
engine running. A common size transformer that would serve this purpose would be 24VA
.
