Each reservoir also has a float assembly which operates a switch. The float operates the switch at a specified level (between 2.0 and 2.3 l in the Blue reservoir and between 2.6 and 3.4 l in the Green and Yellow reservoirs), and shows that the fluid contents are dangerously low.
The contents of the hydraulic reservoirs are shown - on a mechanically-operated gage on each reservoir, - on an electrical reservoir quantity indicator on the ground-service panel
of the Green system,
- on the ECAM system display (HYD page).
The low level switches send signals to the ECAM system and to the overhead panel.
4. Power Supply____________
The AC bus 131XPA supplies 26 V AC through the circuit breaker 1831GQ. It is used for synchro excitation of the synchro transmitters. The same 26 V AC supply is used for excitation of the synchro in the reservoir quantity indicator on the Green ground-service panel. The reservoir quantity indicator has light emitting diodes (LED) and filament lamps which use the same supply. The DC bus 103PP supplies 28 V DC through circuit breaker 1832GQ to the three low level switches in the reservoirs.
5. Component Description_____________________ (Ref. Fig. 002)
A. Gage-Transmitter
The gage-transmitter has four primary assemblies. They are
-
a float and arm assembly, together with a mechanism to change the movement of the arm so that it turns the synchro,
-
a synchro transmitter,
-
a mechanical contents gage,
-
a sealed outer case.
The float is attached to the lower end of the arm. The other end of the arm is attached to a spindle which is held in bearings and turns a gear wheel. The gear wheel turns a pinion which is connected to a permanent magnet. A second permanent magnet is attached to one end of the synchro rotor which turns in bearings and has the indicator pointer on its other end. The two magnets are not mechanically connected and are divided by a part of the casing. The movement is transmitted by magnetic influence, so it is not possible for fluid to get from the reservoir into the synchro and gage assembly.
Gage-Transmitter
Figure 002
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The mechanical contents gage is the end part of the casing and is secured with screws to the primary casing. The case is made of metal and has the electrical receptacle installed on it. It has a boss and bolt holes to install it on the reservoir.
B. Low Level Switch
(Ref. Fig. 003)
The low level switch is installed in the reservoir and gives a signal when the fluid level is too low. It is a float-operated switch which includes a relay. The float assembly includes a magnet which keeps the contacts of a reed switch open when the float is high. When the level of the fluid decreases, the float falls and the reed switch closes. This causes the relay to operate and a signal is sent to the system data acquisition concentrator (SDAC) and to the overhead panel. A metal shroud is around the float. This shroud operates as a damper of small changes in the level of the fluid.
C. Reservoir Quantity Indicator 1834GR
(Ref. Fig. 004)
The reservoir quantity indicator is installed on the ground-service panel of the Green system. It shows the contents of the reservoir which the filling selector valve is set to.
The indicator has a cylindrical case which contains a synchro. On one end of the case there is the electrical receptacle. The indicator face is on the other end. The indicator has three colored scales (one for each reservoir) and three lights which show which system the indicator is set to. Lighting of the indicator face is given by three lights installed in the indicator. The Green and Yellow system indicators are LED; all of the other lights (including the Blue system indicator) are filament lamps.
6. Operation_________ (Ref. Fig. 005)
Changes in the level of fluid in the reservoir cause the float of the transmitter to move the arm assembly. The arm turns its pivot which is connected with gears to the first permanent magnet. Magnetic influence transmits the movement to the second permanent magnet. The second magnet turns the synchro rotor which sends a signal to the ECAM system and to the reservoir filling selector. At the same time the pointer on the synchro gives a visual indication of the contents of the reservoir. The ECAM system gets the signal from the synchro and changes it to an analog display of the contents of the reservoir.
Low Level Switch
Figure 003
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