User manual

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6. Technical Notes and FAQ

6.1 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.

6.2 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 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.

Step Down Transformer Connections on Speed Sensing Cable

#10

12VAC

Secondary

Winding

Step Down Transformer

120VAC

Primary

Winding

To Generator Output

Line to Neutral 120VAC

Twisted pair of wires connected to

speed sensing terminals on GSC300