The invention relates to a
compressed air supply
system (100) for a sensor cleaning device (301) with a
compressed air connection (1), a
compressed air supply connection (2), a pneumatic main line (12) from the compressed air connection (1) to the compressed air supply connection (2) and an
air dryer (5, 5.1) arranged in the pneumatic main line (12) for
drying the compressed air (120). The invention proposes a water separator (6) arranged in the main line (12) between the compressed air connection (1) and the
air dryer (5, 5.1) and a
branch line (14, 14.1, 14.2) extending from the pneumatic main line (12) between the water separator (6) and the
air dryer (5, 5.1) and reconnecting between the air dryer (5, 5.1, 5.2) and the compressed air supply connection (2), which has a pneumatic
branch line switching valve (24, 24.1, 24.2) which in a first operating mode (B1) controls the
branch line (14, 14.1, 14.2).2) opens pneumatically in the direction of the compressed air supply connection (2), and the compressed air supply
system (100) is configured in the first operating mode (B1) to allow compressed air (141) to return from the
branch line (14, 14.1, 14.2). The invention further relates to a compressed air supply
system (1200), a vehicle (1000) and a method (2000) for operating a compressed air supply system (1200).