DOC AIRBUS | AMM A320FOIL PRESSURE INDICATING SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. Oil Pressure Transmitter
Oil Pressure Transmitter LocationA. Description
- The oil pressure transmitter is located on the lubrication unit outlet line.
- Power supply: 28VDC from busbar 202PP.
- Pressure range: 0 to 100PSID.
- Output voltage: 0.7VDC to 9VDC varying linearly with pressure from 0 to 100PSID.
- Accuracy: plus or minus 1PSID, from 0 to 100PSID.
B. Operation
The pressure transmitter operates on the principle of measuring a pressure by sensing the strain induced in a mechanical element, (in this case a dual cantilever beam). Deflection of the beam causes a change in resistance in the four strain gages connected as a Wheatstone bridge.
These resistance changes result in a Direct Current (DC) output voltage which is proportional to the applied pressure. The assembly is equipped with a mechanical stop: this enables the unit to withstand overpressures greater than ten times the full pressure range without changing the calibration.
Several protection features are depicted in the electronic block diagram.
They include protection from reverse voltage, transients and short circuit. Electromagnetic susceptibility protection is afforded by the welded stainless steel case which encloses the elements.
The pressure transmitter operates on the principle of measuring a pressure by sensing the strain induced in a mechanical element, (in this case a dual cantilever beam). Deflection of the beam causes a change in resistance in the four strain gages connected as a Wheatstone bridge.
These resistance changes result in a Direct Current (DC) output voltage which is proportional to the applied pressure. The assembly is equipped with a mechanical stop: this enables the unit to withstand overpressures greater than ten times the full pressure range without changing the calibration.
Several protection features are depicted in the electronic block diagram.
They include protection from reverse voltage, transients and short circuit. Electromagnetic susceptibility protection is afforded by the welded stainless steel case which encloses the elements.
2. Oil Pressure Indicating
- The analog signal from the oil pressure transmitter is sent to the SDAC1, SDAC2 and the Engine Interface Unit (EIU) which transforms the analog signal into a digital signal.
- The digital signal is then transmitted to the Electronic Centralysed Aircraft Monotoring (ECAM) through the Flight Warning Computer (FWC) and the Display Management Computer (DMC).
- The order of priority has been defined as follows:
SDAC1
SDAC2
EIU. - Scale: oil pressure indication is gratuated from 0 to 100PSI on the ECAM display unit.