- A fan unit consisting of 6 fans, mounts near the center of the cabinet.
- The 3 front fans blow up and the 3 rear fans blow down.
- A removable air filter is provided above and below each fan unit.
Four sensors monitor the cabinet temperature:
- 3 sensors are inside the cabinet top
- 1 sensor is inside the cabinet bottom.
- One of the top sensors affects the speed of the front fans.
- The bottom sensor affects the speed of the rear fans.
- A speed control and thermal alarm circuit in each fan monitors the sensors.
- When a sensor indicates a change in cabinet temperature, the circuit in a fan changes that fan's speed accordingly.
Avaya Definity ECS R9 System Description.pdf