Hamilton Sundstrand Company Gas Fuel Metering Valve HFG2.0 - Manual (Page 25)

Figure 1-12: HFG2.0 System Signal Wiring Diagram
Note: For proper operation of the controller, the voltage between
the control inputs and the negative terminal of the power
supply should be below 200 VDC.
Note: The Serial Return is internally connected to the 120 VDC
input Return.
INSTALLING THE HFG2.0 19