TP-5648 8/935-4 Controller Troubleshooting
Automatic Safety
Shutdowns
Overspeed. The overspeed protection circuit board
monitorsthe frequencyof theL2 outputof thegenerator
set. If the frequency is too high, the SDR relay on the
circuit board energizes. Normally open SDR contacts
then close to energize the K4 relay (LED4 lights). As a
result,thenormallyopenK4Acontactsclosetolatchthe
K4 relay energized.
At the same time the K4A contacts close, normally
closed K4B contacts open to de-energize the FP (fuel
pump) motor and the K25 relay. The normally openK25
contacts then open to de-energize the FS (fuel)
solenoid, turning off the flow of fuel. Withthe fuel supply
and fuel pump both turned off, the engine turns off.
With the engine turned off, the generator output decays
andcauses relays K1 and K5 to de-energize (LED1 and
LED5 go out). The normally open K1D contacts then
open, de-energizing the K2 relay (LED2 goes out) and
opening the normally open K2 contacts to interrupt
power to the remaining controller relay circuits,
including relay K4. As a result, the latch-up of the K4
relayisbrokentoreturnthecontrollercircuitstoanormal
pre-start condition.
Engine Safety Switches. The engine is equipped with
up three to five switches that monitor critical operating
conditions. These switches include:
D A High Engine Temperature Switch that closes
when the cooling water is not circulating properly
andtheenginetemperaturerisestowardanunsafe
level.
D A Low Oil Pressure Switch, which closes when the
oil pressure is insufficient, to indicate inadequate
lubrication of the engine.
D An optional Water Temperature Switch, which
closes when the cooling water temperature is too
high, to indicate inadequate cooling of the engine.
D An optional, customer-installed Low Fuel Level
Switch to detect near empty conditions of the fuel
storage tank and thereby prevent complete
emptying of the fuel supply lines and pump.
During normal running, closing any one of the above
switches results in an engine shutdown. During startup,
this shutdown function is disabled by normally open
contacts of the K5 relay until the generator output
stabilizes at acceptable levels as described on page
5-2.)
OncethenormallyopencontactsofK5close,theengine
safetyswitchesareenabled.Ifanyoftheswitchesclose,
the K4 relay is energized to produce a shutdown in the
same manner as described above for an Overspeed
condition.
12 VDC
GP GLOW PLUGS
GP
M
FS
S
10 A.
K25
K25
FP
10 A.
ES
START
STOP/
PREHEAT
K1C
K1D
K1E
K2
K20
K3
K4
K2
K3
K20
S
B.C.
ALT
LED3
LED2
K1F
K4A
HIGH
WATER
TEMP
LOW
OIL
PRESSURE
LOW
FUEL
LEVEL
HIGH
ENGINE
TEMP
K2
SDR
K4
LED4
K7
K7
K5
K6
K7
K1B
K1A
V
1.5 A.
1.5 A.
HZ
A2
A1
MAIN FIELD
L2
LO
LO
L1
SDR
OVERSPEED
PROTECTION
CIRCUIT BOARD
VOLTAGE
REGULATOR
LED1 LED5
K1 K5
F
Figure 5-4. Sequence of Operation,
Emergency Shutdowns
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