Subsation 3.pdf

. SUBSTATION DESIGN  Substation Equipments ❑ Switchyard Accessories I. Power transformer. Power transformers are used to convert high-voltage power to low- voltage power and vice versa. Power can flow in both directions: from the high-voltage side to the low-voltage side or...

. SUBSTATION DESIGN  Substation Equipments ❑ Switchyard Accessories I. Power transformer. Power transformers are used to convert high-voltage power to low- voltage power and vice versa. Power can flow in both directions: from the high-voltage side to the low-voltage side or from the low-voltage side to the high-voltage side.  Substation Equipments II. Instrument Transformers. The term instrument transformer refers to current and voltage transformers that are used to scale down actual power system quantities for metering, protective relaying, and/or system monitoring equipment. a). Current Transformers. Current transformers or CTs are used to scale down the high magnitude of current flowing in high-voltage conductors to a level much easier to work with safely.  Substation Equipments b). Voltage Transformers. Similarly, potential transformers (PTs) are used to scale down very high voltages to levels that are safer to work with.  Substation Equipments III. Circuit Breakers. The purpose of a circuit breaker is to interrupt current flowing in the line,transformer, bus, or other equipment when a problem occurs and the power has to be turned off.  Substation Equipments IV. Disconnector Switches There are many purposes for disconnect switches in substations and power lines. They are used to isolate or deenergize equipment for maintenance purposes, transfer load from one source to another  Substation Equipments V. Lightning Arresters. There are many purposes for disconnect switches in substations and power lines. They are used to isolate or deenergize equipment for maintenance purposes, transfer load from one source to another  Substation Equipments VI. Capacitor Bank Capacitors are used to improve the operating efficiency of electric power systems and help transmission system voltage stability during disturbances. Capacitors are used to cancel out the lagging current effects from motors and transformers. Capacitors can reduce system losses and help provide voltage support.  Substation Equipments VI. Reactors Reactors are used to help regulate transmission system voltage by absorbing surplus reactive power (VARs) from generation or line charging and reduce fault current in distribution lines.