Hobart 9OC24S Operation Manual page 169

FOBART
8
f
QD
;MOTOR GENERATOR DIVISION
e
"b
d
HOBART BROTHERS COMPANY
b . a ,,++
OPERATION, MAINTENANCE.,. AND OVERHAUL MANUAL, TM-240A
SELF-PROPELLED GENERATOR SET, SPEC. NO. 5381A
(36) Check engine oil pressure at governed speed (2400 RPM). Gage should indicate
at least 45 PSI when the engine is hot.
Check engine coolant temperature.
Gage should indicate in the range of 165 degrees to 195 degrees depending
upon ambient temperature.
(37)
Check ope ra ion of fuse interlock (Ref. l-l, Figure 7, item 2). With unit
t
operating normally under load, remove protective relay circuit fuse [Ref.
Figure 2, item (38)l.
The load contactor should open immediately. This
indicates that the fuse interlock relay is functioning properly. Replace
fuse and apply load.
NOTE: Make all protective relay tests with the unit operating under load.
(38) Check operation of overvoltage relay and indicating light.
(a) With the unit running at normal load, adjust thevoltage regulator rheo-
stat (46, Fig. 2) to increase voltage (turn clockwise) until the overvoltage
sensing relay actuates the protective monitor to open the load contactor
and turn on the overvoltage indicating light. The overvoltage sensing
relay should trip when voltage reaches 130 V to 134 V.
(b) Return unit to normal operating conditions by adjusting voltage regulator
rheostat and pressing reset switch (39).
(39) Check operation of undervoltage sensing relay, indicating light, and time delay.
Before starting this check, let us understand the sequence of events which
should happen when voltage is reduced to 103 V or lower. At some value between
103 V and 93 V, the undervoltage sensing relay (Ref. l-1, Fig. 7, item 5) should
function to activate the undervoltage time delay circuit. Five seconds after the
time delay circuit is activated (if the undervoltage condition continues), it should
function to open the protective monitor relay which, in turn, will open the load
con tactor to stop power de I ivery.
As a result of the action, the undervoltage
indicating light (36) should be turned ON. A stop watch or sweep-second-hand
watch is required for this check. Proceed as follows:
(a) With unit running at normal load, use the voltage regulator rheostat (46,
Fig. 2) to reduce voltage to 104 V. The load contactor should NOT open
after a 5-second delay.
(b) Reduce voltage in steps of 1 V, with a delay of at least 5 seconds between
steps. Restart stopwatch or note position of sweep-second-hand each time
voltage is reduced. At some voltage value between 103 V and 93 V, and
5 seconds after a new voltage setting is made, the load contactor should be
opened and the undervoltage indicating light should be turned on by the
step-by-step action of the undervoltage sensing relay, time de lay circuit,
~- --~----~---and-protective- mon-i-tar-relay.
_ .Qct 30/!73 -.-- -. . ..~ -~~.. _,.... ..- _... ..__ L. -. ~.- ..-- .-.~~~- .- ._~_~.. .- . - . . . ___ . . _._...... ._2.:3