DC POWER DISTRIBUTION (FIGURE FO-1, SHEETS 2 AND 3) - Continued
Power to the optional winterization system is applied whenever the DEAD CRANK SWITCH is set to NORMAL. If
the winterization kit is turned on at its control panel, +24 Vdc is output to TB5-15. This applies power to the two
resistor heaters used to keep the LCD displays in the GSC and the DVR from freezing. There is also a thermally
operated switch in the control panel that closes when the temperature falls below -20 10 F (-28.9 5.6 C). This
switch applies +24 Vdc from TB4-17 to the resistors used to keep the LCD displays in the GSC and the DVR from
freezing. Note that this power is only available when the ECS is not in OFF.
Coolant Low Sensor Interface
Pins P7-7, 8, 9, 13, 14, 24, 30, and 31 are connected between the GSC and connector J37. P7-9 is +8 Vdc
power for the Coolant Low sensor. P7-31 is power return. P7-13 is the Coolant Low signal from the sensor. This
sensor detects presence or absence of coolant in the engine and provides an output indicating that the coolant
level is dangerously low to allow an operator to add coolant before a forced shutdown occurs.
Load Sharing Module (LSM) A4
The LSM gets an input from the Speed Setting Potentiometer (SSP) (labeled FREQUENCY on the front panel).
This signal allows the generator frequency to be adjusted 10% of nominal. There is a SYNC input on pins 24
and 25 from the GSC. This signal is output on LSM Pins 10 and 11 if this generator is connected to a dead load
bus and in AUTO or SEMI-AUTO sync mode. Otherwise, pins 10 and 11 are an input. Pins 10 and 11 are
connected to J32 and J33 through contacts on the paralleling relay (PAR). J32 and J33 are the paralleling cable
connectors on the rear of the generator set near the control panel. In parallel operation, cables interconnect all of
the paralleled generators and these ports are all in parallel. Pins 19 and 20 are a serial communication port to the
ECM via J37. Pins 15 and 16 are power and ground respectively.
Alarm Module A2
The alarm module monitors three conditions: Low Fuel, Overload (current), and Short Circuit (OL/SC). The Low
Fuel condition is monitored by fuel level switch FL1 in the fuel tank and a set of contacts close when the fuel tank
is almost empty. This lights a red lamp on the alarm panel and sounds the alarm buzzer. The lamp will flash at
two cycles per second. Pressing the Alarm Silence button on the alarm module will silence the buzzer. This Low
Fuel signal is also connected to the GSC at P7-23 (SP-1 input) to notify the GSC that the fuel tank is almost
empty. The OL/SC module monitors the Overload and Short Circuit conditions. (The AC Power Distribution
discussion describes the module functions.) A set of relay contacts for each condition is input to this panel and
each lights a yellow lamp. These conditions do not sound the buzzer. There is a relay coil (AR) connected to the
LAMP TEST input/output of the alarm panel. When the LAMP TEST button on the panel is pressed, this relay is
energized. The contacts (FO-1, sheet 2) remove power from the OL/SC module when the relay is energized.
This resets the output relays and any condition sensed by this module. Power for this module is on pins 1 and 7.
Dead Bus Hi/Lo Inputs
Spare input SP-4 at P7-29 is connected to ground through a set of contacts on DBHI and a set of contacts on
DBLO. If there is no voltage on the load bus, DBLO and DBHI will both be de-energized and the contacts used
here will both be closed, grounding P7-29. This input is monitored to verify the condition of the load bus. A
ground here indicates that there is no voltage on the load bus. This input is compared against the AC voltage
monitored at P7-17 and P7-18. If both signals indicate a dead bus, the AUTO mode will close the load contactor
onto the dead bus automatically.