The warning signal device is a device that can automatically emit audio and optical card light signals when the equipment fails or some abnormal operation conditions. It can help operators to detect faults and hidden dangers in time to take appropriate measures to deal with them and prevent the expansion of accidents.
Common warning signals of substation include: light gas action of transformer, transformer overload, high oil temperature of transformer, secondary circuit disconnection of voltage transformer, DC circuit insulation reduction, control circuit disconnection, circuit fuse of accident audio signal, high or low DC voltage.
Trailer signals are generally sent from individual relays monitoring operating parameters such as overload signals by overload protection relay.
The warning signal is divided into instantaneous warning signal and delay signal. Some warning signals that may be accompanied by a short circuit failure in the power system, such as overload and voltage transformer secondary circuit disconnection, shall be issued with delay.
The delay shall be greater than the maximum removal time limit of the external short circuit. Thus, these abnormalities caused by the system short circuit automatically disappear without sending an alarm signal to distract the operator.
At present, the trailer signal device with repeated action has the same action principle as the accident audio signal device with the alarm bell. FIG. 11 shows the wiring diagram of the ZC-23 type impact relay. The action principle is similar to FIG. 9. The Fig. KM1 is drawn by FIG. 15 to automatically remove the sound, and WSW1 and WSW2 are the instantaneous warning busbus.