Preparation For Power Delivery; Power Delivery (Manual Voltage Control); Discontinue Power Delivery; Stopping The Engine - Hobart 6921 Series Operation And Maintenance Manual

OM-2040 / Operation and Maintenance Manual
90D20 / Generator Sets
f. Preparation for Power Delivery (Manual Voltage Control)
Preparation for power delivery using manual voltage is exactly the same as for automatic control
[Para. 2, B, (1) thru (2) above] except:
(1) Place automatic-manual switch (31) in MANUAL position.
(2) Set the manual voltage control rheostat (30) near its mid-range position.
g. Power Delivery (Manual Voltage Control)
Power deliver using manual voltage control is the same as automatic delivery [para. E, (1) thru (5)
above] except:
(1) Control generator output voltage by adjusting the rheostat (30, Fig. 1) to maintain a steady
115-VAC reading on the voltmeter (3) . Turn the rheostat (30) knob CLOCKWISE to INCREASE
voltage and COUNTERCLOCKWISE to DECREASE voltage.
(2) Adjust voltage to 115 VAC.
(3) During manual power delivery the operator must remain with the generator set to adjust output
voltage for varying loads and conditions.
h. Discontinue Power Delivery
(1) Place the load contactor switch (21) in OFF position. Green light (23) should go OFF
immediately to indicate that the load contactor has opened and power is no longer being
delivered to the aircraft.
(2) Place engine-generator control switch (21) in IDLE position.
(3) Disconnect output cable from aircraft.
WARNING
High voltage! Electric shock or fire can kill! Never disconnect the output cable
while power is being delivered.
i. Stopping the Engine
(1) Allow the engine to idle a few minutes before stopping to permit cooling.
(2) To stop the engine, move switch to stop position (26) .

3. Transformer-Rectifier Operation

Tranformer-Rectifier operating instructions are contained in their respective manuals, however, some
generator set instructions are required here.
a. Direct Current Power Delivery
NOTE: If the customer adds a Tranformer-Rectifier to a standard machine which was NOT equipped
with a T-R when it left the factory, he must remove the jumper lead which will be found on the
small terminal strip in the generator set voltage regulator (see 1-1; 19, Fig. 12). If your generator
set has a factory installed T-R, the jumper will have been removed.
(1) When delivering power from only one T-R (28.5-V, 35-V, OR 112-V DC) prepare the generator
set for DC power delivery the same as for AC delivery, except do not connect AC output cable
and do not close AC load contactor.
(2) For T-R operating instructions:
See OM-433 for 28.5 V DC T-R Operating Instructions
See TM-598 for 112-V DC T-R Operating Instructions
Chapter 1-3
Page 6
February 28/94 Revised