A self-closing vent has its frame and honeycomb screen coated with an intumescent material. At least one strain gauge sensor is mounted to the internal web to measure the shearing stress within the web as the wrench is rotated. The synchronizing the data includes synchronizing the data in a parameter change record table stored in a Customer Premises Equipment. Each redundancy circuit comprises a switch and resistor electrically in series. The flexible diaphragm divides the metallic vessel into a storage space and a pneumatic room. The composite magnetic bearing of a radial type provided around a rotor having an auxiliary bearing coupled thereto for reducing friction, includes a magnetic bearing, and an auxiliary bearing fixed in the empty space in an inside of the stator cores on an inner side of a position the coils and the permanent magnets are provided thereto.