Guardian 4721, Руководство по ремонту

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TEST 4 - TEST THERMAL PROTECTOR
DISCUSSION:
An open thermal protector will result in loss of excita-
tion. Generator AC output voltage will then drop to a
residual voltage.
PROCEDURE:
1. Locate DPE Wire No. 2 where it connects to the excita-
tion circuit breaker. Disconnect the wire from the circuit
breaker.
2. Disconnect DPE Wire No. 6 from the voltage regulator.
3. Set a VOM to its “Rx1” scale and zero the meter.
4. Connect the VOM test leads across Wires No. 2 and 6.
The meter should indicate the resistance of the stator
excitation (DPE) winding.
5. If the meter indicated INFINITY in Step 4, connect the
VOM test leads across Wire No. 5 (bypass wire) and Wire
No. 6. The meter should indicate the resistance of the
stator excitation (DPE) winding.
NOTE: Normal DPE Winding Resistance across
Wires No. 2 & 6 is:
15 kW . . . . . . . . . . . . . . . . . . . . 0.635 ohms.
20 kW . . . . . . . . . . . . . . . . . . . . 0.056 ohms.
25 kW . . . . . . . . . . . . . . . . . . . . 0.041 ohms.
RESULTS:
1. If normal DPE winding resistance was indicated in Step
5, but INFINITY is indicated in Step 4, bypass the thermal
protector by connecting Wire No. 5 to the excitation circuit
breaker (CB1). See Figure 2.
2. If normal resistance is indicated in Step 4, go to Test 5.
Figure 2. Bypassing the Thermal Protector
TEST 5 - FIXED EXCITATION TEST
/ROTOR AMP DRAW TEST
DISCUSSION:
Supplying a fixed DC current to the rotor will induce a
magnetic field in the rotor. With the generator run-
ning, this should create a proportional voltage output
from the stator windings.
PROCEDURE:
1. Disconnect Wire 4 from the voltage regulator, third termi-
nal from the top. See Figure 3.
2. Connect a jumper wire to the disconnected Wire 4 and
to the 12 volt fused battery supply Wire 15. (located at
15A fuse).
Figure 3. Voltage Regulator
3. Set VOM to AC volts.
4. Disconnect Wire 2 from the excitation circuit breaker
(CB2) and connect one meter test lead to that wire.
Disconnect Wire 6 from the voltage regulator and con-
nect the other meter test lead to that wire. (5th terminal
from top, double check wire number).
5. Set the AUTO-OFF-MANUAL switch to MANUAL. Once
the engine starts, record the AC voltage.
6. Set the AUTO-OFF-MANUAL switch to OFF. Reconnect
Wire 2 and Wire 6.
7. Disconnect Wire S15 from the voltage regulator and
connect one meter test lead to that wire. Disconnect
Wire S16 from the voltage regulator and connect the
other meter test lead to that wire (both wires are located
at the top two terminals of the voltage regulator, see
Figure 3).
S15
S16
0
4
4
6
162
VR - VOLTAGE REGULATOR
TP - THERMAL PROTECTOR
(BYPASS)
WIRE
NUT
DPE - STATOR EXCITATION WINDING
CB2
DPE
TP
2
6
5
CB2 - EXCITATION CIRCUIT BREAKER
162
162
6
6
VR
PART 2
Page 32
PREPACKAGED LIQUID
COOLED AC GENERATORS
SECTION 2.4
DIAGNOSTIC TESTS