Me kana da High Voltage Switchgear?

Mai Huwa High Voltage Switchgear?

Takardar da High Voltage Switchgear

High voltage switchgear yana nufin kayayyakin da ke magance volts daga 36KV zuwa hagu na tsawon bayanai don inganta tattalin arziki da kuma gudummawa masu kyau.

Komoponentoci Masu Yawan

High voltage circuit breakers, kamar air blast, oil, SF6, da vacuum circuit breakers, sun fiye wajen koyar da currents masu high voltage.

Kunna Baka ga High Voltage Circuit Breaker

Kunna baka ga high voltage circuit breaker, don inganta gudummawa da kuma amfani da breakers a cikin high voltage switchgear, ya kamata su zama suke amfani da su da dalilai,

• Faults na terminal.

• Faults na line mai tsawo.

• Transformer ko reactors magnetizing current.

• Energizing long transmission line.

• Charging capacitor bank.

• Switching of out of phase sequence.

Air Blast Circuit Breaker

A cikin wannan takarda, an yi amfani da blast na high pressure compressed air don quench arc bayan iya haɗa duhu masu contact, inda ionization na arc column ta shafi shekaru zero.

Oil Circuit Breaker

Wannan ana koyar da ita kamar bulk oil circuit breaker (BOCB) da minimum oil circuit breaker (MOCB). A cikin BOCB, interrupting unit yake a cikin tanki na oil na earth potential. Hakan oil yana amfani a matsayin insulating da kuma interrupting medium. Amma a cikin MOCB, an iya kadan insulating oil requirement tare da amfani da interrupting units a cikin chamber na insulating na live potential a cikin insulator column.

SF6 Circuit Breaker

SF6 gas yana amfani a cikin high voltage applications don quench arc. Sulfur hexafluoride gas yana da electronegativity mai yawa, da dielectric da arc quenching properties mai kyau. Wannan properties sun ba high voltage circuit breakers suke designed da dimensions masu tsawo da contact gaps masu tsawo. Insulating ability na mafi yawa take taimaka a kammala indoor type switchgear don high voltage systems.

Vacuum Circuit Breaker

A cikin vacuum, ba za a sami ionization daga biyu masu contact masu iya haɗa duhu ba, bayan shekaru zero. Arc na farko take yi waɗanda ya shiga ita zai ci gaba a nan lokacin da shekaru zero ya shiga amma saboda ba za a sami provision don ionization a nan lokacin da shekaru ya shiga shekaru zero, arc quenching take buƙaci. Idan an yi amfani da VCB a cikin high voltage switchgear, amma har yanzu ba shi ba shi ne babban ƙarfin don high voltage level saboda ba shi ba shi ne economical.

Abubuwan Switchgear

• Gas Insulated Indoor Type (GIS),

• Air Insulated Outdoor Type.

Management of Faults

Yanzu load na da mu'amala kan power system yana da inductive nature. Saboda hakan inductance, idan short circuit current yake iya haɗa duhu da circuit breaker, akwai ƙananan da aka sani don high restriking voltage na high-frequency oscillation a tsari na few hundred Hz. Wannan voltage yana da biyar ƙaramin

Transient recovery voltage na high frequency oscillation immediately after the arc extinction.Ba a dole high frequency oscillation, power frequency recover voltage yake shiga across the CB contacts.

Transient Recovery Voltage

Immediately after the extinction of arc transient recovery voltage yake shiga across the CB contacts, na high frequency. Wannan transient recovery voltage yake ci gaba open circuit voltage. Wannan recovery voltage zai iya tabbatar da ita a cikin

Frequency na oscillation yana kasa da parameters L da C. Resistance na power circuit yana damsa wannan transient voltage. Transient recovery voltage ba shi ne single frequency, shi ne combination of many different frequencies saboda complexity na power network.

Power Frequency Recovery Voltage

Wannan ba shi ne open circuit voltage shiga across the CB contacts, immediately after the transient recovery voltage damse. A cikin three phase system power frequency recovery voltage yana ƙarin daga faze na ɗaya.

Idan neutral na network ba shi ne earthed, voltage across the first pole to be cleared yana 1.5U inda U shi ne phase voltage. A cikin earthed neutral system, yake 1.3U. An iya kadan magnitude and rate of rising of transient recovery voltage tare da amfani da damping resistor.

Dielectric recovery of the arc quenching medium and rate of rising of transient recovery voltage yana taimaka a kan performance of the circuit breaker used in high voltage switchgear system. A cikin air blast circuit breaker, once ionized air is de-ionized very slowly, thus air takes a long time to recover dielectric strength.

Saboda hakan ita yana da kyau a amfani da low-value breaker resistor don kadan rate of rising of recovery voltage.

Amma ABCB yana da ƙwarewa a initial recovery voltage saboda high arc voltage a cikin SF6 circuit breaker, interrupting medium (SF6) yana da faster rate of recovery of dielectric strength, than air. Lower arc voltage makes SF6 CB more sensitive to the initial recovery voltage.

A cikin oil circuit breaker, during arc having pressurized hydrogen gas (produced during recombination of oil due to arc temperature) provides quick recovery of dielectric strength immediate after current zero. Hence OCB is more sensitive to rate of rise of recovery voltage. It is also more sensitive to initial transient recovery voltage.

Short Line Fault

Short line fault a cikin transmission network yana nufin short circuit faults occurred, within 5 km of the line length. Double frequency being impressed on the circuit breaker and the difference of source and line side transient recovery voltage, both voltages start from instantaneous values at the opposition of the circuit breakers prior to the interruption.

On the supply side, the voltage will oscillate at supply frequency and ultimately approaches to open circuit voltage. On the line side, after interruption, trapped charges initial traveling waves through the transmission line, since there is no driving voltage on the driving side, the voltage ultimately becomes zero because of the line losses.