FUNCTIONING OF EQUIPMENT
SECTION I. GENERAL
3-1. Scope. This chapter provides a functional description of the power distribution box. The circuits are
explained to the extent necessary for general support maintenance.
3-2. Organization. In addition to the functional description contained herein, refer to TM 32-5865-012-10 for
operating instructions for the power distribution box. The following description references block diagrams and
schematic diagrams. Block diagrams are provided in the text or as foldout drawings. The schematic diagrams
are provided as foldout drawings. Foldout drawings referenced in the text as FOs are located at the rear of the
SECTION II. FUNCTIONAL DESCRIPTION
3-3. Power Distribution Box. Refer to figure FO-1. The power distribution box contains separate ac and dc
control circuits, separate ac and dc power distribution circuits, and an RFI filter assembly. Safety features are
provided in the form of interlock jumpers on two rear panel connectors.
a. Control Circuits. The ac and dc control circuits consist of relays K1 thru K4, switch S1, circuit
breakers CB6 and CB21, and interlock jumpers on connector J2. As shown in figure 3-1, external equipments
and switch functions are required to complete operation of the control circuits.
(1) DC Control Circuit. The +28 V dc input is applied to the power distribution box at connector pin J7-E.
DC return is provided at connector pin J7-B. The input passes to the dc control circuit when CONTROL circuit
breaker CB21 is set to on (in), the closure is made between connector pins J8-C and J8-D (normally switched
by external equipment), and power distribution box MISSION POWER switch S1 is set to ON. The dc input
illuminates MISSION POWER on lamp DS1 and operates relays K3 and K2. When relay K3 operates, contacts
Al and A2, B1 and B2, and C1 and C2 close to pass the +28 V dc input to circuit breakers CB9 thru CB20 in the
dc power distribution circuit. When relay K2 operates, contacts Al and A2, B1 and B2, and C1 and C2 close to
pass the 115 V ac input to circuit breakers CB1 thru CB8 in the ac control and power distribution circuits.