Dual Output Machine - Hobart 6921 Series Operation And Maintenance Manual

OM-2040 / Operation and Maintenance Manual
90D20 / Generator Sets

7. Dual Output Machine

When a machine is equipped with the second output option, the unit has two output circuits for servicing
two aircraft simultaneously, or for servicing a single aircraft with two input receptacles. The output
terminal boards for this unit are arranged as illustrated in Figure 16, with output No. 1 at the rear
terminal board and output No. 2 at the front. This dual output assembly is mounted in the same location
as the single output terminal board on the single output unit (10, Fig. 3) . Components of the dual output
circuits are identical to the components of the comparable single output units, but are grouped
separately as follows:
a. Contactor switch for the second output is located in a small box attached to the frame in front of the
engine control panel (Fig. 17) . This box also includes the No. 2 contactor CLOSED light which glows
green when the No. 2 contactor is closed. These parts are identical to items 8 and 10 on Fig. 10.
b. The power module panel for output No. 2 (Fig. 18) is mounted on brackets directly above the power
module panel for output No. 1 (12, Fig. 3) . The load contactor, rectifier and blocking diode are identical
to items 5, 6, and 8, Figure 13. The two relays, TEST BANK switch and resistor are identical to items 1,
2, 18, and 21, Figure 9.
c. A flyback diode has been added to the No. 2 output circuit across pins 2 and 10 of the fuse interlock
relay socket. This diode prevents any inductive voltage discharge into the circuit when the relay coil is
deenergized. Its counterpart in the No. 1 output circuit is an integral part of the over-undervoltage relay
(5, Fig. 9) .
d. Protective circuits described in Para. 2 monitor and protect output No. 2 as well as output No. 1.
Chapter 1-1
Page 24
1. Test box
2. Cable
3. Plug connector
Test Box Assembly
(Optional)
Figure 15
February 28/94
Revised