DOC AIRBUS | AMM A320FBRAKE SYSTEM TEMPERATURE - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The brake temperature system comprises:
The brake temperature system comprises:
- four temperature sensors (one chromel-alumel thermocouple per brake),
- two brake-temperature monitoring units (one per gear),
- one braking/steering control unit (BSCU).
A. Temperature Sensor
The chromel-alumel temperature sensor delivers a voltage proportional to the temperature difference between the cold junction and the hot junction.
It is possible to obtain a signal proportional to the brake temperature if you cancel the term k theta j from the equation.
The compensator resistor does this function.
The chromel-alumel temperature sensor delivers a voltage proportional to the temperature difference between the cold junction and the hot junction.
Temperature Sensor - PrincipleIt is possible to obtain a signal proportional to the brake temperature if you cancel the term k theta j from the equation.
The compensator resistor does this function.
B. Brake-Temperature Monitoring Unit
The brake-temperature monitoring unit is equipped with two printed circuits required to:
The brake-temperature monitoring unit is equipped with two printed circuits required to:
- process the data from the temperature sensor,
- compensate the thermocouple cold junction.
- Send a voltage proportionnal to the temperature to the BSCU.
C. BSCU
The BSCU changes the analog signals from the brake-temperature monitoring unit into an ARINC 429 signal. The BSCU sends these data and the BRAKE HOT warning to the lower ECAM DU.
The BSCU changes the analog signals from the brake-temperature monitoring unit into an ARINC 429 signal. The BSCU sends these data and the BRAKE HOT warning to the lower ECAM DU.
2. Component Location
The temperature sensor located on each brake is housed in the torque tube. A brake-temperature monitoring unit is installed on each main gear.
The BSCU is installed on shelf 94VU in the electronics rack 90VU.
** ON A/C NOT FOR ALL The temperature sensor located on each brake is housed in the torque tube. A brake-temperature monitoring unit is installed on each main gear.
The BSCU is installed on shelf 94VU in the electronics rack 90VU.
| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 2GW | MONITORING UNIT-BRK TEMP, R | 741 | 32-47-18 | ||
| 3GW | MONITORING UNIT-BRK TEMP, L | 731 | 32-47-18 | ||
| 4GW | SENSOR-BRK TEMP, WHEEL 3 | 741 | 32-47-15 | ||
| 5GW | SENSOR-BRK TEMP, WHEEL 1 | 731 | 32-47-15 | ||
| 6GW | SENSOR-BRK TEMP, WHEEL 4 | 741 | 32-47-15 | ||
| 7GW | SENSOR-BRK TEMP, WHEEL 2 | 731 | 32-47-15 | ||
3. Operation/Control and Indicating
A. Principle of Operation
Each brake-temperature monitoring unit receives the voltages from the two temperature sensors.
After processing, the electronic circuits deliver a voltage proportional to the temperature of each brake heat-sink. This voltage varies between 1V and 9V, which corresponds to a temperature range of 0 to 999 deg.C (1830.20 deg.F).
In the BSCU, the four voltage values are compared to a voltage corresponding to an overheat threshold of:
The four ARINC 429 values go to the lower ECAM DU.
When the brake temperature remains lower than the overheat detection threshold, the temperature values are shown green. The highest temperature has a green arc above it (if > 100 deg.C (212.00 deg.F)). When a temperature value exceeds the detection threshold it is shown amber.
A difference between the temperature of two brakes higher than 100 deg.C increases the brightness of the temperature indication of the hottest brake.
Each brake-temperature monitoring unit receives the voltages from the two temperature sensors.
After processing, the electronic circuits deliver a voltage proportional to the temperature of each brake heat-sink. This voltage varies between 1V and 9V, which corresponds to a temperature range of 0 to 999 deg.C (1830.20 deg.F).
In the BSCU, the four voltage values are compared to a voltage corresponding to an overheat threshold of:
- 300 deg.C (572.00 deg.F). If the temperature of a brake is more than 300 deg.C (572.00 deg.F), a BRAKE HOT warning message is shown on the upper ECAM DU.
The four ARINC 429 values go to the lower ECAM DU.
When the brake temperature remains lower than the overheat detection threshold, the temperature values are shown green. The highest temperature has a green arc above it (if > 100 deg.C (212.00 deg.F)). When a temperature value exceeds the detection threshold it is shown amber.
A difference between the temperature of two brakes higher than 100 deg.C increases the brightness of the temperature indication of the hottest brake.
B. Temperature Sensor to Brake-Temperature Monitoring Unit Connections
The connections from the temperature sensor to the brake-temperature monitoring unit are in chromel-alumel.
In the event of rupture of at least one wire of the thermocouple, the brake-temperature monitoring unit sends a high signal > 9V to the BSCU (normal range : 1V = 0 deg.C, 9V = 1000 deg.C (1832.00 deg.F)). The failure is detected and a flag comes into view on the ECAM DU.
In the event of a short circuit between the two thermocouple connecting wires, the temperature indicated is low.
In the event of a short circuit between the line and ground the temperature indicated is high.
90% of the electronic failures lead to an out-of-range signal < 1V or > 9V.
The connections from the temperature sensor to the brake-temperature monitoring unit are in chromel-alumel.
In the event of rupture of at least one wire of the thermocouple, the brake-temperature monitoring unit sends a high signal > 9V to the BSCU (normal range : 1V = 0 deg.C, 9V = 1000 deg.C (1832.00 deg.F)). The failure is detected and a flag comes into view on the ECAM DU.
In the event of a short circuit between the two thermocouple connecting wires, the temperature indicated is low.
In the event of a short circuit between the line and ground the temperature indicated is high.
90% of the electronic failures lead to an out-of-range signal < 1V or > 9V.