Doosan G20 SIIIA, Руководство по эксплуатации и техническому обслуживанию

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114 G20, 30, 40 SIIIA Operation & Maintenance Manual
Checking the winding
You can check the winding insulation by performing a
high voltage test. In this case, you must disconnect all
AVR wires.
CAUTION
Damage caused to the AVR in such conditions is not
covered by our warranty.
Checking the diode bridge
A diode in good working order should allow the current to
flow only in the anode to cathode direction.
Checking the windings and rotating diodes using
separate excitation
During this procedure, make sure that the alternator
is disconnected from any external load and inspect
the terminal box to check that the connections are
fully tightened.
1. Stop the unit, disconnect and isolate the AVR wires.
2. There are two ways of creating an assembly with
separate excitation.
Assembly A: Connect a 12 V battery in series with a
rheostat of approximately 50 ohms - 300 W and a diode
on both exciter field wires (5+) and (6-).
Assembly A
Assembly B: Connect a “Variac” variable power supply
and a diode bridge on both exciter field wires (5+) and
(6-).
Both these systems should have characteristics which
are compatible with the field excitation power of the
machine (see the nameplate).
3. Run the unit at its rated speed.
4. Gradually increase the exciter field current by
adjusting the rheostat or the variac and measure the
output voltages on L1 - L2 - L3, checking the
excitation voltage and current at no load (see the
machine nameplate or ask for the factory test report).
When the output voltage is at its rated value and
balanced within 1% for the rated excitation level, the
machine is in good working order. The fault therefore
comes from the AVR or its associated wiring (i.e.
sensing, auxiliary windings).
Assembly B
A n o d e C a t h o d e
+R
+R
+
-
-W
-W
IN
IN
IN
IN
6 - 5 +
Diode 1A
12V battery
Rh. 50
Ω
- 300W
-
+
ASSEMBLY A
Exciter field
Diode 1A
-
+
6 -
5 +
Variac AC
220V
DC
12V
50
60
70
08
90
100
40
30
02
10
0
ASSEMBLY B
Exciter field