Generac Power Systems 53187 - Manual (Page 122)

SECTION 5.5
ENGINE PROTECTIVE DEVICES 1
g. As the fluid tem perature drops below about 245‘-
266' F., the sw itch contacts should open and the
m eter should indicate 'infinity*.
test.
Replace the high tem perature sw itch if it faiis the
HIGH COOLWr
TEMFeVJVRE «•
SHLTT DOWN'
SWITCH TESTING
TW W 40W ETE»'
//7 m i
/ ,
Figure 3. Testing Coolant T em perature Sw itch
Overspeed Protection
General; Generator AC frequency signals are de­
livered to Term inals 5 and 6 of the engine control circuit
board, via W ires 11 and 22. Should engine-generator
speed exceed approxim ately 69-71 Hertz (2070-2130
rpm ), and should such an overspeed last longer than
about four (4) seconds, circuit board action w ill cause
an engine shutdow n.
Testing Overspeed Shutdow n: To test over­
speed shutdow n operation proceed as follow s:
1. Connect an accurate AC frequency m eter to Term i­
nals 5 and 6 of the engine control circuit board (W ires
11 and 22).
2. Start the engine, let it stabilize and w arm up. DO NOT
CONNECT ANY ELECTRICAL LOADS DURING THE
TEST.
3. Slow ly increase engine speed until the frequency
m eter reads about 69 Hertz. Then, slow ly increase
speed to just slightly m ore than 71 Hertz. After a four
(4) second delay, the engine should shut dow n.
Adjusting Overspeed Shutdow n: To adjust the
overspeed setting at w hich engine shutdow n occurs,
proceed as follow s:
1. See Figure 4. Turn the OVERSPEED SHUTDOW N
POTENTIOMETER all the w ay clockw ise against its
stop. DO NOT FORCE.
2. Start the engine, let it stabilize and w arm up at
no-load.
3. Connect an AC frequency m eter across circuit board
term inals 5 and 6 (W ires 11 and 22).
PART 5
ENGINE ELECTRICAL SYSTEM
4. SLOW LY increase engine speed until the frequency
m eter reads about 70 Hertz. Hold that setting, then
SLOW LY
turn the OVERSPEED SHUTDOW N PO­
TENTIOM ETER counterclockw ise (CCW ) IN VERY
SMALL INCREMENTS. W ait about four (4) seconds
betw een each increm ental adjustm ent. W hen engine
shuts dow n, overspeed shutdow n setting is correct.
Figure 4. Engine Control Circuit Board
PAGE 5.5-2