EQUIPMENT.

 (3)  
Connect an external power cable to the P19 receptacle.

 S 864-014

 (4)  
Energize the external power cable.

 (a)  
Make sure that the EXTERNAL POWER - CONN and NOT IN USE lights on the P19 panel come on.

 (b)  
Make sure that the GRD POWER AVAILABLE light on the P5-4 panel comes on.

 WARNING:_______ BEFORE YOU CONNECT THE EXTERNAL POWER CABLE TO THE AIRPLANE,
 MAKE SURE THE EXTERNAL POWER CABLE IS NOT ENERGIZED.
 ELECTRICAL ARCS CAN CAUSE INJURY TO PERSONS AND DAMAGE TO

 S 864-015
 (5)  Push the BAT switch on the P5-13 panel to ON.
 (a)  Make sure that these lights on the P5-4 panel come on: 1) TRANSFER BUS OFF 1 and 2 2) BUS OFF 1 and 2 3) GEN OFF BUS 1 and 2
 S 864-016
 (6)  Push the GROUND SERVICE switch on the forward attendant's panel to ON.
 (a)  Make sure that the EXTERNAL POWER - NOT IN USE light on the P19 panel goes off.
 S 864-017
 (7)  Push the GRD PWR switch on the P5-4 panel to ON.
 (a)  
Make sure that these lights go off: 1) TRANSFER BUS OFF 1 and 2 2) BUS OFF 1 and 2

 (b)  
Make sure that the GROUND SERVICE switch moves to the OFF position.

 S 864-009
 (8)  Remove the external power if it is not necessary (AMM 24-22-00/201).
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 24-41-21
 ALL  ú ú 01 Page 403 ú Nov 15/90
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
 1.

2.

3.

4.

A
737-300/400/500MAINTENANCE MANUAL
 ELECTRICAL LOAD DISTRIBUTION - DESCRIPTION AND OPERATION
________________________________________________________
General (Fig. 1)
_______
 A.  Electrical load distribution consists of 115-volt ac buses, 28-volt ac buses, and 28-volt dc buses.
 B.  Except for the external power contactor and the generator No. 1 and No. 2 circuit breakers which are in the right hand forward compartment outboard of the nose wheel well, the contactors, relays, main circuit breakers, and other major components are in the load control center panel P6. The fronts of the panels contain circuit breakers. The panels are hinged along the edge which permits swinging the panel forward. When the panels are opened, components are accessible. The control units for the three airplane generators, a receptacle panel to 115-volt ac and 28-volt dc P6-6 and the dc system circuit breaker panel P6-5 are on the left side of load control center P6.
115-Volt AC System (Fig. 2)
__________________
 A.  Engine-driven generator 1 furnishes power to gen bus 1 and engine-driven generator 2 furnishes power to gen bus 2. External power or APU-driven generator can furnish power to either or both buses. Any source of power cannot be paralleled with any other source of power.
 B.  Each gen bus furnishes power to main bus, transfer bus, and elex bus. Gen bus 1 also furnishes power to ground service bus and transfer bus 1 furnishes power to standby bus.
 C.  If either gen bus loses power, the other gen bus furnishes power to both
 transfer buses through transfer relays.28-Volt AC System (Fig. 2)
_________________
 A.  Each 115-volt ac main bus, transfer bus, and ground service bus furnish
 power to 28-volt ac buses through autotransformers.28-Volt DC System (Fig. 2)
_________________
 A.  Each 115-volt ac transfer bus furnishes power to 28-volt dc buses through transformer-rectifier units. The 115-volt ac main bus 2 furnishes power to transformer-rectifier unit 3, which is the back-up power source for 28-volt dc buses. Each 28-volt dc bus furnishes power to an elex bus.
 B.  The battery or battery charger provide power to the hot battery bus. The hot battery bus or T-R 3 provide power to the battery bus.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 24-50-00
 ALL  ú ú 01 Page 1 ú Jun 25/84
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
　
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