high voltage switchgear

More Knowledge About Distribution Substations


A substation is a high-voltage electric system office. It is utilized to switch generators, hardware, and circuits or lines all through a system. It likewise is utilized to change AC voltages starting with one level then onto the next, and/or change alternating current to direct present or direct current to alternating current. A few substations are small with minimal more than a transformer and related switches. Others are expansive with a few transformers and many switches and other hardware. There are three aspects to substations:

Substation Types: Although, there are for the most part four sorts of substations are a combination of two or more sorts.

  • Step up Transmission Substation
  • Step down Transmission Substation
  • Distribution Substation
  • Underground Distribution Substation
  • Substation Functions
  • Substation Equipment

Distribution substations are situated close to the end-users. Distribution substation transformers change the transmission or sub-transmission voltage to lower levels for utilization by end-users. Typical distribution voltages vary from 34,500Y/19,920 volts to 4,160Y/2400 volts.

34,500Y/19,920 volts are interpreted as a three-stage circuit with a grounded neutral source. This would have three high-voltage conductors or wires and one grounded neutral conductor, a sum of four wires. The voltage between the three stage conductors or wires would be 34,500 volts and the voltage between one phase conductor and the neutral ground would be 19,920 volts.

From here the power is distributed to modern, business, and private clients.

Substations are intended to achieve the accompanying functions, although not all substations have every one of these functions:

  • Change voltage starting with one level then onto the next
  • Direct voltage to make up for system voltage changes
  • Switch transmission and distribution circuits into and out of the grid system
  • Measure electric power qualities flowing in the circuits
  • Connect communication signals to the circuits
  • Eliminate lightning and other electrical surges from the system
  • Connect electric generation plants to the system

Make interconnections between the electric systems of more than one utility

Significance Of Switchboards


An electric switchboard is a gadget that directs power from one or more sources of supply to a few smaller areas of utilization. It is a get together of one or more boards, each of which contains switches that permit power to be redirected.

The U.S. National Electrical Code (NEC) characterizes a switchboards as “a large single board, edge, or assemblies of boards on which are mounted, on the face, back, or both, switches, over-present and other defensive gadgets, buses, and generally instruments”. The part of a switchboard is to permit the division of the current supplied to the switchboard into littler currents for further distribution and to give switching, current security and metering for those currents. Switchboards may circulate energy to transformers, panelboards, control equipment, and, at last, to individual system loads.


Inside a switchboard there will be one or more busbars. These are flat pieces of copper or aluminum, to which the switchgear is associated. Busbars bring large currents through the switchboard, and are supported by insulators. Bare busbars are general, yet numerous sorts are manufactured with an insulating covers on the bars, leaving just connection points uncovered.

The operator is shielded from electric shock by safety switches and fuses. There may likewise be controls for the supply of power to the switchboard, originating from a generator or bank of electrical generators, particularly recurrence control of AC power and load sharing controls, in addition to gauges demonstrating frequency and maybe a synchroscope. The power going into a switchboard should constantly equivalent to the power going out to the loads.


Present day modern switchboards are metal encased and of “dead front” construction; no empowered parts are available when the covers and panels are shut. A switchboard may have incoming bus bars or bus conduit for the source connection, furthermore for large circuits fed from the board. A switchboard may incorporate a metering or control compartment separated from the power distribution conductors.

Present day modern switchboards are metal encased and of “dead front” construction; no empowered parts are available when the covers and panels are shut. A switchboard may have incoming bus bars or bus conduit for the source connection, furthermore for large circuits fed from the board. A switchboard may incorporate a metering or control compartment separated from the power distribution conductors.

Segregated Phase Bus Duct- Managing the Low and Medium Voltage Requirements

segregated phase bus

Generation and distribution of electricity is of vital importance for everything nowadays. Every enterprise and every household requires electricity. There are various devices and components which are involved in the production and management of electricity as it is a very complex process. Segregated Phase Bus Duct is one such device which is designed for the low and medium voltage requirements.

The purpose of such designs is to meet specific, continuous and short circuit current ratings and generating stations, substations and industrial distribution systems which can be installed indoors and outdoors. In a segregated bus duct, each phase conductor is separated by a grounded barrier from adjacent phases unlike in non-segregated phase ducts where all phase conductors are in the same enclosure. For conducting large currents between devices, a cable bus is used. For very large currents in generating stations or substations, where it is difficult to provide circuit protection, an isolated-phase bus is used. Each phase of the circuit is run in a separate grounded metal enclosure. The only fault possible is a phase-to-ground fault, since the enclosures are separated. This type of bus can be rated up to 50,000 amperes and up to hundreds of kilovolts (during normal service, not just for faults), but is not used for building wiring in the conventional sense.

One of the greatest advantages of bus ducts is that they are capable of adding or removing a branch circuit without removing voltage from the whole duct. It carries large amounts of amperage across a distance. This is useful in plant design so that you can pull individual leads down from it to machinery. The problem with this is control. If it is installed and the plant does not properly keep up on load documentation, it is easy to overload it. Installing bus duct requires the installer to work with and handle high voltages and currents which can cause instant death. Therefore, it should be done with utmost care and all the necessary precautions should be taken.

High Voltage Switchgear: Knowing the Configuration and Operation

switchgearThe power system deals with voltage above 36KV, is regarded as high voltage. Since the voltage level is high, the arcing formed during switching operation is also quite high. Therefore, special care is to be taken during the designing of high voltage switchgear. High voltage circuit breaker is the major component of HV switchgear, thus high voltage circuit breaker ought to have special features for reliable and safe operation. Switching operation and faulty tripping of high voltage circuit are very rear. At time these circuit breakers remain, at ON state, and might be operated after a long period of time. Thus CBs must be dependable enough to make sure of safe operation, as when necessary. High voltage circuit breaker technology has changed drastically in the last 15 years.

SF6 circuit breaker, air blast circuit breaker and minimum oil circuit breaker are mostly used for high voltage switchgear. Vacuum circuit breaker is hardly used for this purpose since till date vacuum technology is not sufficient for interrupting very high voltage short circuit current. There are two kinds of SF6 circuit breaker, that is, single pressure SF6 breaker and two pressures circuit breaker. Single pressure system is the latest and updated high voltage switchgear system, these days. Nowadays SF6 gas as arc quenching medium has become most accepted for high and extra high voltage electrical power system. Though, SF6 gas has strong influence on the greenhouse effect. It has 23 times stronger influence on the greenhouse effect, than that of CO2. Therefore, leakage of SF6 gas in the service life of circuit breaker should be prevented. For minimizing the emission of CF4 – SF6, N2 – SF6 and SF6 gas mixture, might be used in circuit breaker in future, as an alternate of pure SF6. It should always be taken into consideration that, no SF6 gas comes out in atmosphere throughout the maintenance of CB.