Northern Lights OGSC300 Operator's Manual - page 19
OGSC300 08/12
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6 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 10 seconds to clear the memory, a loss of speed will may
be indicated by the GSC300 (if controller is in AUTO mode and start signal is activated) 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 main power OFF for 10 seconds before main power
is re-applied this allows the clearing the memory 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 steady 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 verifi cation 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.
Figure 6: Step Down Transformer Connections on Speed Sensing Cable