Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

Prevention of incorrect opening/closing of circuit breakers: Mechanical interlock: The operating handle must be inserted into a specific position and operated in sequence, directly restricting incorrect opening/closing. Electrical interlock: The closing circuit of the circuit breaker is connected in series with the auxiliary contact of the disconnector. Closing is prohibited if the disconnector is not fully closed.Prevention of load-breaking operation of disconnectors: Mechanical interlock: The

Gas Insulated Switchgear (GIS) consists of circuit breakers, disconnectors, earthing switches, current transformers, voltage transformers, surge arresters, busbars, connectors, and outlet terminals. With higher reliability, safety, and relatively small space occupation, it is widely used in the design and construction of high - voltage substations. In urban and densely - populated areas, GIS is the preferred choice due to its compact structure and excellent insulation performance.However, 110 kV

Types Electromagnetic Electro-pneumatic PneumaticInterrupting Medium Air Oil SF6 gas VacuumRated values of voltages Rated voltage (Operational voltage)：For a three phase contactors, the voltage between phases is called rated voltage or operational voltage. Rated Insulation Voltage：The voltage, on which performs the dielectric test.Rated Values of Current Rated Thermal Current: The maximum current, on which a Contactor operates continuously for eight (8) hours without increasing the temperature (

The rating of a circuit breaker is determined by the duties it performs. For complete specifications, standard ratings and various tests for switches and circuit breakers should be consulted. In addition to the normal operation of circuit breakers, they are required to perform the following three major duties under short-circuit conditions: Breaking the faulty section of the system, defined as the breaking capacity of the circuit breaker. Making the circuit under the greatest asymmetrical curren

The role of busbars in switchgear：Busbars are conductors in switchgear that collect, distribute, and transmit electrical energy. They connect the power source (such as the output terminal of a transformer) to various branches (such as the incoming terminals of circuit breakers), acting as a transfer station for electrical energy. This enables electrical energy to be distributed to different electrical equipment or circuits as required.Methods for selecting appropriate busbars：Current - carrying

When the current-carrying contacts of a circuit breaker separate, an arc forms and persists briefly after contact separation. This arc is hazardous due to the heat energy it generates, which can produce explosive forces.A circuit breaker must extinguish the arc without damaging equipment or endangering personnel. The arc significantly influences the breaker’s performance. Interrupting aDC arcis inherently more challenging than anAC arc. In an AC arc, the current naturally reaches zero

In an air break circuit breaker, the arc is initiated and extinguished in substantially static air as the arc moves. These breakers are used for low voltages, generally up to 15 kV, with rupturing capacities of 500 MVA. As an arc-quenching medium, air circuit breakers offer several advantages over oil, including: Elimination of risks and maintenance associated with oil use. Absence of mechanical stress caused by gas pressure and oil movement. Elimination of costs from regular oil replacement due

High Rupturing Capacity (HRC) Fuses: Design, Operation, and ApplicationsCore FunctionalityHRC fuses are engineered to safely conduct short-circuit or fault currents for a specified duration. If the fault is cleared within this timeframe, the fuse element remains intact; otherwise, it melts to interrupt the circuit. Encased in an airtight container, the element is shielded from environmental factors while enabling efficient arc quenching.Inverse Time CharacteristicHRC fuses exhibit a criticalinve

Definition and Principle of Impedance Relay (Distance Relay)An impedance relay, also known as a distance relay, is a voltage-controlled protective device whose operation depends on the electrical distance (impedance) between the fault point and the relay’s installation position. It functions by measuring the impedance of the faulty section and comparing it with a pre-set threshold.Working Mechanism Measurement and Comparison: The relay continuously monitors line voltage (via potential

Reactance RelayA reactance relay is a high-speed relay composed of two elements: an overcurrent element and a current-voltage directional element. The current element generates positive torque, while the current-voltage directional element produces torque opposite to the current element, depending on the phase angle between the current and voltage.The reactance relay is an overcurrent relay with directional limitation. The directional element is designed to generate maximum negative torque when