Power Delivery (Automatic Voltage Control) - Hobart 6921 Series Operation And Maintenance Manual

OM-2040 / Operation and Maintenance Manual
90D20 / Generator Sets
e. Power Delivery (Automatic Voltage Control)
(1) Place generator mode control switch (17, Fig. 1) in BUILD-UP-VOLTAGE position momentarily
then allow it to position itself in GEN position. The electric governor will immediately increase
engine speed to 2000 RPM and maintain it.
(2) Observe generator instruments. Frequency meter (1, Fig. 1) should indicate exactly 400-Hz;
voltmeter (3) should indicate 115 VAC when line switch (7) is in LINE-TO-NEUTRAL position.
(3) The final step in delivering power is closing the load contactor.When satisfactory frequency and
voltage values are indicated by the instruments, close the load contactor by momentarily placing
the load contactor control switch (21) in the top (spring-loaded) ON position. The green
indicating light (23) should glow at once to indicate that the load contactor is closed and power is
available at the aircraft. As soon as the light glows, release the switch. It will automatically
return to the center ON position.
NOTE: If the indicating light (23) should "go-out" as soon as the switch is released, and no fault lights
are ON, it indicates that 28.5-VDC holding current is not being supplied from aircraft to the
plug-interlock relay. Correct the condition and again operate the load contactor control switch
(21) as above.
(4) It is recommended that the operator check output voltage and current in each of the three
phases early in the power delivery run.Use the meter switch (6) to select the phase. Use the
line switch (7) to select line-to-line or line-to-neutral voltage. If the load is changing, it is good
operating practice to observe the instruments until load conditions stabilize.
(5) The load contactor will automatically open when a condition of over or undervoltage, over or
under frequency, or overload exists in the output circuit. The applicable indicating light will signal
the operator which fault caused the protective monitor system to operate. Reset switch (9) after
the fault has been corrected. The indicator light will turn off, and the protective relay system will
reset. Proceed with power delivery by operating the load contactor switch.
February 28/94 Revised
1. Clamp Screw
2. Fluid Cylinder
3. Cap
4. Plug
Cold Weather Starting Aid
(Optional)
Figure 2
Chapter 1-3
Page 5