Generac Power Systems NP-40G - Manual (Page 18)

Section 1.4- INSULATION RESISTANCE
Test All Stator Windings to
Ground (Continued)
EXAMPLE: Generator rated voltage Is "120 VAC".
Divide
■ ...............................................■
obtain
the unit Is "1.12 megohms".
120 by 1000 to obtain "0.12". Add “1" to
"1.12 . Minimum Insulation resistance for
Test for Shorts Between Windings
Figure
2
on the previous page shows the Stator leads
that are brought out of the Stator. Figure 3 is a schematic
representation of the eight (8) Stator windings. To test
for shorts between windings, proceed as follows:
1. Make sure all Stator output leads are isolated from
each other and from the frame.
2. POWER PHASE TO TIMING WINDINGS:- Connect one
tester probe to Stator lead No. 11, the other test probe to
Stator lead TIM1. Apply a voltage of 1000 volts. The
Tester will Indicate a breakdown if the windings are
shorted together.
3. POWER PASE TO POWER SUPPLY WINDINGS: Con­
nect one tester probe to Stator lead No. 11, the other
tester probe to Stator lead PS1. Apply 1000 volts. If a
breakdown Is Indicated, the windings are shorted to­
gether.
4. POWER PHASE TO BATTERY CHARGE WINDINGS:-
Connect one tester probe to Stator Lead No. 11, the other
probe to Stator lead No. 55. Apply 1000 volts. If break­
down Is Indicated, the windings are shorted together.
5. TIMING TO POWER SUPPLY WINDING:- Connect one
tester probe to Stator lead No. TM1, the other test probe
to Stator lead No. PS1. Apply 1000 volts. If breakdown is
Indicated, the windings are shorted together.
6. TIMING TO BATTERY CHARGE WINDING:- Connect
one test probe to Stator lead No. TIM1, the other test
probe to Stator lead No. 55. Apply 1000 volts. If break­
down is Indicated the windings are shorted together.
7. POWER SUPPLY TO BATTERY CHARGE WINDING:-
Connect one test probe to Stator lead No. PS1, the other
probe to Stator lead No. 55. Apply 1000 volts. If break­
down is indicated, the windings are shorted together.
Results of Tests
1. If testing Indicates that Stator windings are shorted to
ground, the Stator should be cleaned and dried. The
Insulation resistance tests should then be repeated. If,
after cleaning and drying, the Stator again fails the test,
replace the Stator assembly.
2. If testing Indicates that a short between windings
exists, clean and dry the Stator. Then, repeat the tests. If
Stator fails a second test (after cleaning and drying),
replace the Stator assembly.
Cleaning the Generator
GENERAL:
If testing indicates that the insulation resistance is
below a safe value, the winding should be cleaned.
Proper cleaning can be accomplished only while the
generator is disassembled. The cleaning method used
should be determined by the type of dirt to be removed.
Be sure to dry the unit after it has been cleaned. An
electric motor repair shop may be able to assist with
cleaning. Such shops are often experienced in special
problems (sea coast, marine, wetland applications, etc.).
Figure 3. Schematic- Stator Windings
POWER
PHASE 1
pravm ппушт|
AC1
I
AC2
h
PHASE 2
POWER ^
SL1
à 11
SL2
h
f
POWER
SUPPLY
PS1 PS2 .
О ^ О
TIMING
TIMI T1M2
BATTERY
CHARGE
USING SOLVENTS FOR CLEANING:
A solvent is generally required when dirt contains oil
or grease. Only petroleum distillates should be used to
clean electrical components. Recommended are safety
type petroleum solvents having a flash point greater than
100’ F. (38* C.).
Use a soft brush or cloth to apply the solvent. Use care
to avoid damaging magnet wire or winding Insulation.
After cleaning, dry all components thoroughly with mois­
ture-free, low pressure compressed air.
DANGER!
DO NOT WORK WITH SOLVENTS IN ANY EN­
CLOSED AREA. ALWAYS PROVIDE ADEQUATE
VENTILATION. FIRE, EXPLOSION OR OTHER
HEALTH HAZARDS MAY EXIST UNLESS ADE­
QUATE VENTILATION IS PROVIDED. WEAR EYE
PROTECTION. WEAR RUBBER GLOVES TO PRO­
TECT THE HANDS.
CAUTIONI
Some generators use epoxy or polyester base
winding varnishes. Use solvents that do not at­
tack such materials.
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