Transformer core grounding
When the power transformer is operating normally, the iron core must be reliably grounded at one point. If there is no grounding, the floating voltage of the iron core to the ground will cause intermittent breakdown discharge of the iron core to the ground. After the iron core is grounded at one point, the possibility of forming a floating potential of the iron core is eliminated.
However, when the iron core is grounded at more than two points, the uneven potential between the iron cores will form circulating currents between the grounding points, causing multi-point grounding heating failures in the iron core. A ground fault in the core of the transformer will cause local overheating of the core. In severe cases, the local temperature rise of the core will increase, causing light gas operation, or even causing a tripping accident due to heavy gas operation.
The difference between neutral point, zero point and zero line
The common connection point where the first ends (or tail ends) of the three-phase windings are connected together is called the power supply neutral point. When the neutral point of the power supply is well connected to the grounding device, the neutral point is called the zero point; and the wire leading from the zero point is called the neutral line.
The difference between electric energy meter and power meter
The electric energy meter can simultaneously indicate active and reactive power and count and power factor, load curve, maximum and minimum load time, etc.;
The power meter can only indicate a single active or reactive power value.
The dangers of casing cracks
Cracks in the casing will reduce the insulation strength and cause further damage to the insulation until complete breakdown. Water in cracks may also cause the casing to burst when it freezes.
The role of the central signaling device
The central signaling device includes accident signals and warning signals, which are installed on the central signal screen in the main control room of the substation. When the circuit breaker of any distribution device in the substation trips accidentally, the accident signal is activated; when abnormal operation occurs or the operating power supply fails, the warning signal is activated. Accident signals and warning signals have both audio and light signaling devices. The audio signal can arouse the attention of the personnel on duty, and the light signal can help the personnel on duty determine the nature and location of the fault.
Internal overvoltage
Internal overvoltage is a sudden change in the state of the system due to operation, accidents or other reasons, which will lead to a transition process from one stable state to another. During this process, there may be dangerous overvoltage to the system.
The function of high voltage circuit breaker
1. The role of control. When there is no-load current in the circuit, or when the current load is relatively large, it can cut off or close in time, thereby controlling the entire circuit.
2. The role of protection. When a circuit failure occurs, such as a short circuit or an open circuit, it can pass through the high-voltage circuit breaker and have the ability to interrupt current. With this protection function, it can prevent circuit problems.
