A: The main functions of the transformer are: ① used to insulate the secondary equipment such as instruments and relays from the main circuit. ② It is used to expand the application range of instruments, electrical appliances and other secondary equipment. Voltage transformer installation: ① pay attention to the secondary side do not short circuit. ② One end of the secondary side must be grounded. ③ Pay attention to the installation of the terminal polarity current transformer: ① Do not open the secondary side. ② One end of the secondary side must be grounded. ③ Pay attention to terminal polarity