14
INSTALLATION AND MAINTENANCE
LSA R 49.1 Air/air heat exchanger
ALTERNATORS - Ex II 3 G
SERVICING - MAINTENANCE
4081 en - 09.2006 / a
LEROY-SOMER
4.5.1 - Checking the winding
You can check the winding insulation by performing a high
voltage test. In this case, you must disconnect all AVR wires.
Damage caused to the AVR in such conditions is not
covered by our warranty.
4.5.2 - Checking the diode bridge
4.5.3 - 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-).
WARNING : Adapt the diode to the rated excitation
current of the alternator (see nameplate).
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 machine field excitation power (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 and on 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 (ie. sensing, auxiliary windings).
WARNING
WARNING
DIODE BRIDGE
C
A
A n o d e
C a t h o d e
-
C
A
+
-
C
A
+
A diode in good
working order must
allow the current
to flow from the anode
to the cathode.
-
-
C C C
A A A
~
~
~
C C C
A A A
~
~
~
+
+
~
~
~
C C C
A A A
C C C
A A A
~
~
~
6 -
5 +
1A diode
12V battery
Rh. 50 -300W
-
+
ASSEMBLY A
Field
1A diode
-
+
6 -
5 +
Variac
AC
220V
DC
12V
50
60
70
80
90
100
40
30
20
10
0
ASSEMBLY B
Field