Murphy Series A900 - Manual (Page 24)

(c) “Water Temperature” light will come on and engine will
stop.
(d) Turn Mode Selector switch OFF.
4-4.9 Low Water Temperature; to test the low water temperature
alarm circuit:
(a) Engine does not have to be running.
(b) Use a jumper wire and short from terminal 31 to 4.
(c) “Low Water Temperature” alarm light will come on as long
as the jumper maintains the circuit.
4-4.10 Other Alarm and/or Shutdowns; all other alarms and
shutdowns would be tested in the same manner.
(a) For shutdown circuits, the engine must be running for test.
(b) Most alarm only circuits can be tested without starting the
engine. Low Oil Pressure Pre-alarm and High Water
Temperature Pre-alarm are exceptions.
(c) To test other shutdowns or alarms, a jumper wire can be
used to short out the switch contacts at the switch or if this
is not possible, the test can be run by shorting the input
terminal for that circuit, to ground, terminal 4.
(d) To test Low Oil Pressure Pre-alarm;
1. Turn Mode Selector switch to TEST. When engine
starts, wait 30 seconds then,
2. Use a jumper wire and short from terminal 50 to 4;
“Low Oil Pressure Pre-alarm” light will come on as
long as the jumper maintains the circuit.
(e) To test High Water Temperature Pre-alarm;
1. Turn Mode Selector switch to TEST. When engine
starts, wait 30 seconds then,
2. Use a jumper wire and short from terminal 51 to 4;
“High Water Temperature Pre-alarm” light will come
on as long as the jumper maintains the circuit.
Section 5: Operation
5-1 Operator Controls.
5-1.1 Mode Selector Switch; allows the operator to select either
manual (TEST), automatic operation (AUTO), or no operation
(OFF).
5-1.2 The OFF position on the mode selector also provides a
reset function for the shutdown circuits. If the engine is shut
down by the automatic control, the operator must turn selector
off and back on to reactivate the system.
5-1.3 Push to Test Lamps; this pushbutton tests the alarm and
shutdown indicator lights.
5-1.4 Alarm Silence Pushbutton; if so equipped, silences the
local and remote audible alarm. Visual indicator remains on
until reset or sensor switch contacts clear.
5-2 Operating Modes.
5-2.1 The A900 Generator Engine Control has two operating
modes: manual and automatic.
5-2.2 Manual Operation is provided for testing of the generator
set.
5-2.2.1 To initiate Manual Control, place the Mode Selector
switch in the TEST position. This provides the automatic
control a start signal.
5-2.2.2 To stop, turn selector switch to OFF. This removes start
signal and the engine will stop.
5-2.3 Automatic operation is the normal mode.
5-2.3.1 To initiate Automatic Control, place the Mode Selector
switch in the AUTOMATIC position. When a start signal is
received, the engine will start.
5-2.3.2 When the start signal is removed, the engine will stop.
It is now ready to restart.
5-2.4 OFF or Not Operating; to prevent operation of the engine,
turn selector switch OFF.
Section 6: Routine Maintenance
and Operational Tests
6-1 Routine Maintenance.
6-1.1 Due to the design and types of components used, very
little maintenance is required to the A900 Control.
6-1.2 Visual inspection of the internal wiring of the control
panel, along with checking wire connections for tightness,
should be done on a semiannual schedule for stand-by systems
or quarterly for prime power. Check wire bundles for chafing
and wear to the insulation of the wires where they contact the
panel or engine.
6-1.4 Shutdown and Alarm Circuits should be tested on a
monthly basis for prime power and quarterly for stand-by sets.
The same tests run during pre-operation check out, Section 4-4,
should be included.
6-2 Operational Tests.
6-2.1 No special operational tests are required. The routine
operational tests for the generator set will exercise the control.
Section 7: Troubleshooting and Repair
7-1 Tools Required.
7-1.1 Some of the tools necessary for troubleshooting are built
into the A900 Series controls.
7-1.1.1 By observing the lights on the front and rear of the control
panel, clues to a problem and the possible source can be seen.
7-1.1.2 Operational problems with the automatic engine control
will show up by looking at the input and output lights on the rear
of the A900 SELECTRONIC
® Control / Display Module.
7-1.2 Other tools which may be required are:
7-1.2.l AC/DC Voltmeter for taking voltage readings and an
Ohmmeter for testing resistance of wires and connections.
7-1.2.2 Jumper wires with alligator clips to bypass or simulate
circuit closures.
DO NOT USE THESE JUMPER WIRES TO CHECK IF
VOLTAGE IS PRESENT AT A TERMINAL BY DRAWING
AN ARC TO GROUND. THIS WILL DAMAGE OR
DESTROY EQUIPMENT IN THE A900 CONTROL PANEL.
7-2 A900 SELECTRONIC Control Operation And
Shutdown.
7-2.1 The first step in troubleshooting any equipment is to
understand its normal operation. Table 7-2.1 contains normal
voltage readings taken at the terminals of the A901 with all
equipment shown on the standard drawing, connected.
(a) All voltage readings are DC, except at terminal 29, and
were taken with the negative lead of the meter connected
to ground at terminal 4. Voltage reading at terminal 29
was taken with negative lead grounded and the meter on
AC scale.
(b) The battery voltage, at the time readings were recorded,
was 13.8 V and 27.6 V. All readings will vary depending
on battery voltage, equipment supplied in the panel and
external devices connected to the A900 control. See notes
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