(b)
Make sure that the ON light in the EXT PWR switch (P5) is on.
(c)
Push the R BUS TIE switch (P5) to the ISLN (out position).
(d)
Make sure that the lights on P5 panel that follow are on: 1) The amber right BUS OFF light. 2) The amber ISLN light in the right BUS TIE switch.
(e)
Push the GROUND SERVICE switch on the forward attendant panel P21. 1) Make sure that the white light in the GROUND SERVICE switch
stays on.
S 864-016
(3) Remove electrical power if it is not necessary (AMM 24-22-00/201).
G. If current transformer T111, or T115 was replaced do a test as follows:
S 864-017
(1)
Supply APU generator power to the left main ac bus
(AMM 24-22-00/201).
S 864-020
(2)
Make sure that the lights on P5 panel that follow are off:
(a)
The OFF light in the APU GEN switch.
(b)
The ISLN light in the L BUS TIE switch.
(c)
The L BUS OFF light.
S 714-018
(3) Push the GROUND SERVICE switch on the forward attendant panel P21.
(a) Make sure that the white light in the GROUND SERVICE switch stays on.
S 864-019
(4) Remove electrical power if it is no longer required
(AMM 24-22-00/201).
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
24-23-01
ALL ú ú 01 Page 404 ú Sep 28/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757 MAINTENANCE MANUAL
HYDRAULIC MOTOR GENERATOR SYSTEM - DESCRIPTION AND OPERATION
____________________________________________________________
1. General_______
A. The hydraulic motor generator (HMG) system is an independant, non-time-limited, standby electrical power supply. It is activated automatically in flight when power loss occurs at both main AC buses.
B. System components are a hydraulic motor generator, generator control unit, relays, test switch, hydraulic shutoff valve, hydraulic flow limiters, and a hydraulic accumulator with charging valve and pressure gage.
C. EICAS displays status and maintenance messages for the system.
D. The system is driven by the left hydraulic system.
E. This power source supplies ac power to the L and R 115v ac transfer buses and the captains 115v ac flight instrument transfer bus. It also provides DC power to the hot battery bus. The buses in turn supply selected flight essential loads.
F. AIRPLANES WITH 10 KVA HYDRAULIC MOTOR GENERATOR; It uses a TR unit to transform AC power to DC power before it is supplied to the hot battery bus.
2. Component Details (Fig. 1)_________________
A. AIRPLANES WITH 5 KVA HYDRAULIC MOTOR GENERATOR;
Hydraulic Motor Generator (5kva)
(1) The hydraulic motor generator is on the inboard bulkhead of the left wheel well.
(a) Generator 1) The generator is oil-cooled, and brushless. 2) The generator operates at 12000 rpm and develops ac and dc
outputs. The ac output is 3-phase, 4-wire, wye connected, rated at 115/200 volts rms, 400 Hz, 5.0 KVA at 0.75 to unity power factor. The dc output is supplied by a 3-phase delta-connected winding feeding into a full-wave diode rectifier bridge network. The dc output is rated at 28 volts dc, 50 amps. The ac and dc output ratings apply concurrently.
3) A permanent magnet generator section provides 3-phase 800 Hz power to the generator control unit for control and protection functions.
4) A permanent magnet generator section supples 3-phase output to a full-wave rectifier bridge for main field excitation. Excitation is controlled by the generator control unit to maintain a nominal 118v rms line to neutral at the end of the ac feeders in the P71 panel. The dc output is unregulated except for indirect control of the ac regulation.
(b) Motor
1) The hydraulic motor is a servo-controlled, 12000 rpm constant speed variable displacement unit designed for operation in a 3000-psi hydraulic system. The nominal flow rate to the unit is 9.5 gpm when supplying extended range operation loads. Peak flow rate during low pressure transient conditions is approximately 17 gpm.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AIRPLANES WITH HYDRAULIC MOTOR GENERATOR ú
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本文鏈接地址：757 AMM 飛機(jī)維護(hù)手冊(cè) 電源 ELECTRICAL POWER 1(99)
