Appareillage et protection

Medium-voltage switchgear controls and protects electrical distribution systems between low-voltage utilization and high-voltage transmission. It is used in utility substations, factories, data centers, mines, buildings and renewable-energy plants. This guide compares air- and gas-insulated, metal-clad and ring-main designs and explains…

The power factor of a motor describes how effectively the motor converts apparent electrical power into real mechanical output. Induction motors normally have lagging power factor because their magnetic field requires reactive current. The value changes with load, voltage, speed,…

To know whether power factor is leading or lagging, determine the direction of reactive power and the phase relationship between voltage and current. Inductive loads such as motors and transformers normally draw lagging current. Capacitors normally supply leading reactive current.…

An SF6 circuit breaker is a high-voltage switching device that uses sulfur hexafluoride gas for insulation and arc interruption. The gas has high dielectric strength and can capture free electrons, allowing a compact interrupter to withstand recovery voltage after current…

An air switch circuit breaker is an air-insulated switching and protection device that uses the surrounding air as its arc-insulation medium. The term is used for several low-voltage devices, including air circuit breakers, panel air switches and manually operated disconnects.…

An electrical cabinet air conditioner keeps control panels, drives, PLCs and protection equipment within their allowable temperature and humidity range. The unit is not selected by cabinet dimensions alone. Start with the heat generated inside the enclosure, the highest ambient…

Miniature circuit breaker vs MCCB is a practical comparison for engineers selecting low-voltage distribution protection. Both devices can interrupt fault current, but their frame size, current range, trip adjustment, accessories, breaking capacity and installation applications differ. The correct choice depends…

A circuit breaker for motor protection must handle normal running current, starting current and fault current without nuisance tripping or leaving the motor and conductors unprotected. A motor branch circuit normally combines short-circuit protection, overload protection, a switching device and…

A shunt-trip circuit breaker has an accessory that opens the breaker when a separate control signal energizes its trip coil. The control circuit may be initiated by an emergency-stop system, fire alarm, remote trip pushbutton, protective relay or building-management system.…