Abstract: The present invention relates to a controller (11), a cabin pressure control system (10) and a method for controlling pressure in a cabin (30), especially an aircraft cabin. In accordance with the invention the controller (11) comprises a channel (15, 16) and a pressure differential safety function (22). The channel (15; 16) calculates a first output signal (40) for actuating an overflow valve (17) in a closed loop control based on the pressure differential between the cabin (30) and the atmosphere and additional critical parameters. The safety function (22) calculates a second output signal (41) based only on the pressure differential. The two output signals (40, 41) are compared, and the second output signal (41) is selected, if said first output signal (40) is found inaccurate. The safety function (22) assures operation of the outflow valve (17) even it the channel (15; 16) is out of function.

Abstract: The present invention relates to a controller (11), a cabin pressure control system (10) and a method for controlling pressure in a cabin (30), especially an aircraft cabin. In accordance with the invention the controller (11) comprises a channel (15, 16) and a pressure differential safety function (22). The channel (15, 16) calculates a first output signal (40) for actuating an overflow valve (17) in a closed loop control based on the pressure differential between the cabin (30) and the atmosphere and additional critical parameters The safety function (22) calculates a second output signal (41) based only on the pressure differential. The two output signals (40, 41) are compared, and the second output signal (41) is selected, if said first output signal (40) is found inaccurate, The safety function (22) assures operation of the outflow valve (17) even it the channel (15, 16) is out of function.