S 424-010
(a) 34B2, GROUND POWER BPCU
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MAINTENANCE MANUAL
S 864-012
(4) Remove the DO-NOT-CLOSE tag and close this circuit breaker on the P6 panel:
(a) 6B4, BUS PWR CONT UNIT
S 864-013
(5) Remove the DO-NOT-CLOSE tag and close this circuit breaker on the P11 panel:
(a) 11R32, BPCU SEC
D. Do a test of the BPCU installation
S 864-014
(1)
Supply external power to the ground handling bus (AMM 24-22-00/201).
S 714-015
(2)
Do a test of the BPCU installation, as follows:
(a)
Push the BAT switch to the ON position at the pilots' overhead panel, P5.
(b)
Push the GROUND SERVICE switch to the on position at the forward attendant panel, P21.
(c)
Make sure the white light in the GROUND SERVICE switch comes on.
(d)
Make sure the NOT IN USE light on the external power panel, P30, is off.
(e)
Push the GROUND SERVICE switch to the off position.
(f)
Make sure the white light in the GROUND SERVICE switch goes off.
(g)
Make sure the NOT IN USE light on the external power panel, P30, is on.
(h)
Push the RESET switch on the BPCU and make sure this sequence of messages show on the BPCU display: 1) EXTERNAL POWER SYSTEM 2) LEFT GEN POWER SYSTEM 3) RIGHT GEN POWER SYSTEM 4) APU GEN POWER SYSTEM
(i)
Push the BAT switch to the OFF position at the pilots' overhead panel, P5.
S 864-016
(3)
Do the activation procedure for the spoilers if you did the
deactivation procedure (Ref 27-61-00).
(4)
Remove electrical power if it is not necessary (Ref 24-22-00).
S 864-017
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AC ELECTRICAL LOAD DISTRIBUTION - DESCRIPTION AND OPERATION
___________________________________________________________
1. General_______
A. Electrical load distribution consists of 115-volt AC buses, 28-volt AC buses, and 28 volt DC buses.
2. General Description (Fig. 1)___________________
A. The main generators supply 115-volt, 3-phase, 400-Hz AC power to the left and right main AC buses. These buses can also be supplied by the APU generator or external power. The main buses feed the following buses: utility buses, galley buses, flight instrument transfer buses, AC center bus, AC standby bus, AC ground service bus, and AC ground handling bus (Ref 24-51-00).
B. The left and right 28-volt AC buses are supplied with power by
autotransformers tied to the main AC buses (Ref 24-53-00).
C. The two main 28-volt DC buses receive power from transformer-rectifier units, which convert main AC bus power. The main DC buses supply power to the DC center bus, DC standby bus, and battery bus (Ref 24-54-00).
D. The ground service system consists of a 115-volt AC bus and a 28-volt AC bus. These buses supply power to loads used on the ground and inflight (Ref 24-51-00).
E. The ground handling system consists of a 115-volt AC bus and a 28-volt DC bus. These buses supply power to ground handling equipment (Ref 24-51-00).
F. AIRPLANES WITH 5 KVA HMG; If power loss occurs at both main AC buses during flight, the hydraulic motor-driven generator is activated automatically, providing ac power to the R and L transfer buses, and dc power to the hot battery bus. The buses in turn supply selected flight essential loads.
G. AIRPLANES WITH 10 KVA HMG; If power loss occurs at both main AC buses during flight, the hydraulic motor generator (HMG) is activated automatically. The HMG supplies ac power to the R and L transfer buses, and the HMG transformer rectifier unit (TRU). The HMG TRU converts the ac power to dc power which is supplied to the hot battery bus. The buses in turn supply selected flight essential loads.
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