Hobart 120CU20, Operation And Maintenance Manual With Illustrated Parts List

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OM-2228 / Operation and Maintenance Manual
120CU20 / Series 500120 / 400 Hz. Generator Set
October 15, 2013 Chapter 1-3
Page 4
CAUTION
To eliminate the possibility of wet stacking (See Appendix A), DO NOT allow the
engine to idle for long periods.
c) Failed Starting Procedure.
CAUTION
To prevent damage to the starting motor, do not engage the starting motor for more
than 30 seconds. Wait two (2) minutes between each attempt to start.
In the event that the engine fails to start, the circuitry must be reset before the next attempt. To do
this:
(1) Push the red “ EMERGENCY STOP/RESET BUTTON” on the control box door to the right of the
control panel.
(2) Pull the red “ EMERGENCY STOP/RESET BUTTON” back out before the next attempt to start
the generator set.
d) Power Delivery
(1) Press “ENGINE START” pushbutton switch a second time to bring engine from idle speed to
rated speed. The ECM will immediately increase engine speed to 2000 RPM and maintain it.
The voltage build-up will occur automatically. In addition, the green indicating light in the
“ENGINE START” push-button switch will glow continuously.
(2) Observe generator instruments. The frequency meter should indicate exactly 400 Hz. With the
“METER SELECT” pushbutton switch set to read any line-to-neutral position, (A-N, B-N, or C-N),
the voltmeter should read 115 volts. With the “METER SELECT” pushbutton switch set to any
line-to-line position, (A-B, B-C, or C-A), the voltmeter should read 200 volts.
(3) The final step in delivering power is closing one or both of the load contactors. When the
instruments indicate satisfactory frequency and voltage values, close either load contactor (or
both load contactors) by momentarily pressing the load contactor(s) (
“OUTPUT NO. 1” or
“OUTPUT NO. 2” ) pushbutton switch. The yellow or orange indicating light of the pushbutton
switch that is pressed will glow continuously, indicating that the load contactor is closed and
power is available at the aircraft.
(4) Early in the power delivery run it is recommended that the operator check output voltage and
current in each of the three phases. Use the “METER SELECT” pushbutton switch to select the
either the line-to-line or line-to-neutral voltage. If the load is changing, observe the instruments
until load conditions stabilize.
CAUTION
NEVER press the test/reset pushbutton switch while power is being delivered.
The contactors will open and power to the aircraft will be suddenly interrupted.
(5) A condition of over-voltage, under-voltage, under-frequency, over-frequency, or overload in the
output circuit will automatically open the load contactor and display a fault code to signal the
operator which of the above faults caused the protective monitor system to operate. After the
fault has been corrected, press the “
TEST/RESET ” push-button switch to reset the protective
relay system. Proceed with power delivery by operating the load contactor pushbutton switch.