| Tweet |
Custom Search
|
|
|
||
 TM 55-1905-223-24-3
(14)
Check the main stator leads for worn insulation. Repair or replace as necessary.
(15)
Recheck to make sure that no control equipment or instrumentation is connected to terminals U, V, W or
N.
(16)
Repeat step (13) as necessary.
(17)
To measure the insulation resistance of the main exciter stator, remove the megger lead from terminal
U and reconnect it to terminal X at the AVR box.
(18)
Crank the megger at approximately 120 rpm (2 turns per second) for 10 seconds and record the
reading.
(19)
A reading of 1.2 megohms or above indicates the insulation resistance of the main exciter stator is
satisfactory.
(20)
A reading of 0.5 to 1.2 megohms indicates the insulation resistance is marginal. Dry the generator and
test again. Refer to step i. of this procedure.
NOTE
* A reading of less than 0.5 megohms indicates an accidental grounding or a severe insulation
problem.
* Check for worn or damaged lead insulation where the X and XX leads go through the terminal box.
Also check where the leads go through the main generator frame. Dry the generator and test again.
Refer to step i. of this procedure.
(21)
Repeat step (20) as necessary.
(22)
To measure the insulation resistance of the permanent magnet exciter windings:
(a) Remove the permanent magnet exciter end cover.
(b) Disconnect the three wire permanent magnet exciter harness at the plug.
(c) Connect one megger lead to any of the t ree prongs extending from the plug.
h
(d) Connect the other megger lead to a convenient part of the frame.
(23)
Crank the megger at approximately 120 rpm (2 turns per second) for 10 seconds and record the
reading.
(24)
A reading of 1.2 megohms or above indicates that the insulation resistance of the permanent magnet
exciter windings is satisfactory.
4-14
|
||
|
||
