Does the high-voltage power distribution cabinet have secondary wiring?
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The high-voltage power distribution cabinet has secondary wiring.
1. **Definition and Functions of Secondary Wiring**
- Secondary wiring refers to the circuit wiring that monitors, controls, regulates and protects the operation of primary equipment. In the high-voltage power distribution cabinet, primary equipment mainly includes high-voltage circuit breakers, disconnectors, buses, current transformers, voltage transformers and other equipment directly used for power distribution and transmission. Secondary wiring is the auxiliary circuit constructed around these primary equipment.
- Its functions include real-time monitoring of the operating status of primary equipment. For example, it can display the operating parameters (such as voltage and current magnitudes) of the equipment through voltmeters and ammeters. Meanwhile, secondary wiring can realize the control of primary equipment. For instance, it can operate the opening and closing of high-voltage circuit breakers through control circuits, thus controlling the on-off of circuits. Moreover, when a fault occurs in the primary equipment, the relay protection devices in the secondary wiring can quickly detect the fault and send a tripping signal to isolate the faulty equipment from the power grid in a timely manner, protecting the safe and stable operation of the entire power system.
2. **Specific Manifestations of Secondary Wiring in the High-Voltage Power Distribution Cabinet**
- **Control Circuit**: The control circuit is used to control the operation of equipment such as circuit breakers. Taking a circuit breaker with an electromagnetic operating mechanism as an example, the control circuit in the secondary wiring includes components such as start buttons, stop buttons, contactors, and relays. When the start button is pressed, the current passes through the control circuit to make the contactor or relay act, thereby connecting the closing coil of the circuit breaker and realizing the closing of the circuit breaker. Similarly, when it is necessary to open the circuit breaker, it is achieved through the opening circuit.
- **Signal Circuit**: The signal circuit is mainly used to indicate the operating status and fault conditions of primary equipment. For example, there are various indicator lights on the high-voltage power distribution cabinet. When the green light is on, it indicates that the circuit breaker is in the open state, and when the red light is on, it indicates that the circuit breaker is in the closed state. When a fault occurs in the primary equipment, the signal relay acts, which will light up the fault indicator light and may also send out an alarm sound to remind the staff to handle it.
- **Measurement Circuit**: The current and voltage signals on the primary side are obtained through current transformers and voltage transformers, and then these signals are transmitted to measurement instruments through secondary wiring. For example, the ammeter is connected in series on the secondary side of the current transformer, and the voltmeter is connected in parallel on the secondary side of the voltage transformer, so that the operating parameters of the primary equipment can be accurately measured.
- **Protection Circuit**:
This is a very important part of the secondary wiring. It consists of various relay protection devices, such as overcurrent protection, overvoltage protection, differential protection, etc. Taking overcurrent protection as an example, when the current in the primary circuit exceeds the set value, the current on the secondary side of the current transformer will also increase accordingly. After the detection and judgment of the protection relay, when the action conditions are met, the protection relay will send a tripping instruction to make the circuit breaker trip and cut off the faulty circuit.
