Abstract: A centrifugal fan includes: an impeller having a back plate; and a scroll casing including a peripheral wall having a volute shape, a first side wall facing a virtual extension of the back plate and an inner end portion of the volute shape of the scroll casing, an expanded portion, and a first edge end portion being an end of a first edge defining the discharge port, of the first side wall, are arranged in a named order in the rotation direction, the first edge end portion being farther from the rotation shaft than an other end of the first edge and distance L1?distance LM>distance LS is satisfied where LS is a distance between the first side wall at the inner end portion of the volute shape and the virtual extension of the back plate, LM is a distance between the first side wall at the expanded portion and the virtual extension of the back plate, the expanded portion being a portion at which the distance between the first side wall and the virtual extension of the back plate is larger than LS, and L1 is a

Abstract: The control section of a control apparatus executes a first control for operating a voltage application section such as to cause a current to flow in a first direction through a gas sensor in a first period, and a second control for operating the voltage application section such as to cause a current to flow in a second direction, opposite to the first direction, through the gas sensor in a second period. The control apparatus changes the length of at least one of the first period and the second period based on a comparison between a first measurement value, which is the absolute value of a value measured by a sweep measurement section during execution of the first control, and a second measurement value, which is the absolute value of a value measured by the sweep measurement section during execution of the second control.

Abstract: The control section of a control apparatus executes a first control for operating a voltage application section such as to cause a current to flow in a first direction through a gas sensor in a first period, and a second control for operating the voltage application section such as to cause a current to flow in a second direction, opposite to the first direction, through the gas sensor in a second period. The control apparatus changes the length of at least one of the first period and the second period based on a comparison between a first measurement value, which is the absolute value of a value measured by a sweep measurement section during execution of the first control, and a second measurement value, which is the absolute value of a value measured by the sweep measurement section during execution of the second control.