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OM-2065 / Operation and Maintenance Manual
90SB51 / Spec. 7015-3 / Frequency Converter
c. Converter Cabinet
The cabinet which houses the converter
apparatus and circuitry consists of a sturdy
welded aluminum frame to which a one-
piece 16-gauge sheet metal cover (3, Fig.
1) is fastened, and to which a flat metal
sheet is attached to form the bottom of the
cabinet. The entire front and rear doors of
the unit are hinged at the bottom to permit
opening the unit for access to serviceable
components. The converter unit is fan-
cooled. Air enters the unit from the bottom
and leaves through the top. Power cables
enter the unit from the rear. These cables
are secured to the unit by clamp assem-
blies mounted in the bottom of the unit.
For servicing convenience where there
may be poor lighting, this unit's cabinet is
equipped with two fluorescent lights. One
of these fluorescent lights comes on
automatically when the front door is
opened to illuminate the front interior
section of the converter and the other
comes on when the back door is opened to
illuminate the rear interior section of the
converter.
d. Bridge Interlock Circuit
For safety, and to prevent damage to
equipment, the converter can be
interlocked with the bridge drive circuitry in
such a way that the bridge can not be
moved on the apron while the converter is
operating. This is done to prevent the
bridge from pulling the output cable from
the airplane or driving over the cable. Each
converter is equipped with a set of normally
closed contacts (on K2 relay) that open
when the converter is operating to disable
the bridge drive circuit. Note that it is
important to disable only the boggie drive
circuit and not the auto leveling circuit on
the bridge. A set of normally open contacts
are also provided on the K2 relay which
can be used to light a "CONVERTER ON"
lamp on the bridge control panel. The K2
relay is the E/F interlock relay and therefore,
the bridge interlock is operated ONLY if
28VDC is being fed back into the converter
through the E/F interlock circuit. See
paragraph 4, A, (2).
Nov 01/90
Bridge Interlock and Optional Remote Push-but-
ton Station Connections
Figure 7
Chapter 1-1
Page 9
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