Fire protection measures can be subdivided into life-safety and investment categories. Life-Safety Measures Life-safety measures are considered to be mandatory by fire codes, building codes, or safety codes. As such, the codes mandate specific types of substation fire protection, with very little flexibility in their selection. Investment Considerations Investment-related fire protection is provided to protect …
Retro perspective 30 years ago: Metal-Clad or Metal-Enclosed MV Switchgear? What to choose?
There are two types of switchgear commonly applied today for switching and protection of in-plant medium voltage (4.16 kV through 34.5 kV) power distribution systems. One is metal-clad switchgear using draw-out air-magnetic or vacuum circuit breakers and relays for both load switching and fault protection: the other is metal-enclosed switchgear using interrupter switches for load switching …
Be extremelly carefull when racking in and racking out of circuit breaker
Arc flash incident, bad racking? There are many reasons causes arc flash incidents. Some of arc flash explosions occur when substation personnel insert or remove (rack in or out) circuit breakers from low or high voltage switchgear cubicles. Manual racking in and racking out circuit breakers poses potentially lethal arc flash exposure. Assumptions and complacency …
Complete overview of lightning arresters (part 3)
Continued from article Complete overview of lightning arresters (part 2) Types of Lightning Arresters for outdoor application There are several types of lightning arresters in general use. They differ only in constructional details but operate on the same principle, providing low resistance path for the surges to the round. Rod arrester Horn gap arrester Multi …
Complete overview of lightning arresters (part 2)
Continued from article Complete overview of lightning arresters (part 1) What is a surge arrester? Surge arresters are devices that help prevent damage to apparatus due to high voltages. The arrester provides a low-impedance path to ground for the current from a lightning strike or transient voltage and then restores to a normal operating conditions. …
Complete overview of lightning arresters (part 1)
Lighting and Voltage Surge Lightning can create voltage surges in several of the following ways. Lightning can score a direct hit on your house. It can strike the overhead power line which enters your house, or a main power line that is blocks away from your home. Lightning can strike branch circuitry wiring in the …
Types of electrical power distribution systems
Electrical power is distribution either three wires or four wires (3 wire for phases and 1 wire for Neutral). Voltage between phase to phase called Line Voltage and voltage between phase and neutral is called Phase Voltage. This forth wire may or may not be distributed in distribution system and same way this neutral may …
GIS vs AIS – Substation Earthing
Compressed SF6 gas used in MV and HV switchgears as an insulating medium has led to the development of compact gas-insulated substation (CIS) technology (figure 1). GIS , having many advantages over often used and conventional air-insulated substations (AIS), have been receiving wide application. However, this alternate technology has inevitably lead to a different set …
Oil-Filled Equipment in Substation – IEEE 980-1994 (R2001)
A number of electrical apparatus installed in substations are filled with oil that provides the necessary insulation characteristics and assures their required performance. Electrical faults in this power equipment can produce arcing and excessive temperatures that may vaporize insulating oil, creating excessive pressure that may rupture the electrical equipment tanks. In addition, operator errors, sabotage, …
AIS – Air insulated substations
Function of Substations Transmission and Distribution Systems In large, modern ac power systems, the transmission and distribution systems function to deliver bulk power from generating sources to users at the load centers. Transmission systems generally include generation switchyards, interconnecting transmission lines, autotransformers, switching stations, and step-down transformers. Distribution systems include primary distribution lines or networks, …
