shear section
(b)
The input spline drives 2 gears to increase the speed of the generator rotor. The gear ratio is 2.96 to 1.
(c)
The assessory gearbox turns at speeds that are between 4630 and 8600 rpm. This causes the generator rotor to turn at speeds that are between 13705 and 25456 rpm.
(d)
The generator makes electrical power which is 3 phase ac at 115 volts and with a variable frequency that is between 1370 and 2545 Hz.
(e)
The electronics in the VSCF change the generator output to a constant frequency of 400 Hz (AMM 24-21-00/001).
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù.
VARIABLE SPEED CONSTANT FREQUENCY ú 24-11-00
GENERATOR/CONVERTERS ú CONFIG 2 ú 02 Page 10 ú Jul 12/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 737-300/400/500MAINTENANCE MANUAL
(2) Cooling and Lubrication (Fig. 4)
(a)
AIRPLANES WITH -14 THROUGH -16 VSCF GENERATOR/CONVERTOR; Cool air from the engine fan keeps the CT/EMI filter, GCCU, dc filter, and ac filter cool. The cool air also removes heat from the oil through the internal heat exchanger and the external oil cooler. This keeps the generator and the inverter cool.
(b)
AIRPLANES WITH -19 AND ON VSCF GENERATOR/CONVERTOR; Cool air from the engine fan keeps the CT/EMI filter, GCCU, dc filter, and ac filter cool. The cool air also removes heat from the oil through the external oil cooler. This keeps the generator and the inverter cool.
(c)
The VSCF uses MIL-L-7808 or MIL-L-23699 oil for cooling and lubrication. The oil also gives viscous damping for the generator bearings to reduce vibration.
(d)
AIRPLANES WITH -14 THROUGH -16 VSCF GENERATOR/CONVERTOR; The oil pump is inside the generator case. It causes 2.0 to
4.5 gallons (7.6 to 17.0 liters) of oil to flow each minute. The flow rate is related to the engine speed.
(e)
AIRPLANES WITH -19 AND ON VSCF GENERATOR/CONVERTOR; The oil pump is inside the generator case. It causes 3.0 to
7.5 gallons (11.35 to 28.39 liters) of oil to flow each minute. The flow rate is related to the engine speed.
(f)
The generator shaft turns the oil pump through a set of gears at a ratio of 1 to 2.27. This keeps the speed of the oil pump below 12,000 rpm. The oil pump keeps approximately 30 psig (207 kPa) of pressure in the oil system. If the oil system becomes blocked, the bypass valve opens at approximately 250 psig (1,724 kPa). This prevents damage to the oil pump.
NOTE: Hamilton-Sundstrand Service Bulletin 24-7 increased
____ the bypass pressure to 350 psi (2,413.16 kilopascal).
(3) Oil Servicing (AMM 12-13-21/301)
(a)
The sight gage on the gearbox shows the level of the oil in the VSCF reservoir, which is inside the inverter. The pressure-fill valve is above the sight glass and lets you add oil to the reservoir through the oil-out line from the VSCF. The oil pump prevents oil flow in the opposire direction during servicing.
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