The fault recorder is mainly used for dynamic recording and fault analysis of generator, transformer, line and generator transformer unit. It can judge whether to start the recording function according to the collected analog quantity and switching value.

Switching value refers to the acquisition and output of discontinuous signal, which has two states of 1 and 0, which is the switching property of digital circuit, while in power, it refers to the opening and closing of the circuit or the connection or disconnection of the contact. "On" and "off" are the basic and typical functions of electrical appliances.

The switch has two states, the first is connected, that is, the closed state, the second is open, that is, the off state. The fault recording device can collect 192 channel switch values, and the switch value can be set to start or on / off start at any time. If there is a sudden quantitative change in the 192 channel switch value, the fault recorder will start the wave recording function and record the quantitative change process and position. In order to help the field staff quickly find the accident point.