Standards of North America: A Comparison Between IEE-Business and Chinese Switchgear Standards

IEEE Std C37.20.9™ ji bo pêşgotina, testkirina û destkirina daneyên li ser gas-insulated switchgear (MEGIS) ku di bi gasekî yên jorîn ji berî tevahî de were bikaranîna wekî taybetîya bingehîn ên sereke yên sisteman di demên dawî de ku piştgiriya ji 1 kV derbas 52 kV hatine nîşan kirin. Ew dibatin, betiyan, bushings, busbars, instrument transformers, cable terminations, meters, û control/protection relays. Di vê daneyên de, qotîlên vertîkan- yekan û hewceyên navendî yên jorîn di bi gasekî yên jorîn de were bikaranîn. Standardekê ji bo destkirina wan di navbera navend û derbar de.

Berî tarîx, cûrên sereke ya daneyên li ser American market air-insulated, metal-clad switchgear bo. Ji bo ring-main distribution applications, American-style pad-mounted transformers werin bikaranîn, ku di navbera transformer core û windings de high-voltage components sivî load switches û high-voltage fuses werin tijî ne. Li gorî vê yekê, gas-insulated switchgear di American market de were qebûl kirin paşîn.

Bi destkirina gas-insulated switchgear ji aliyên European wêç ABB û Schneider Electric di American market de, pelan kevefet û were qebûl kirin. Li gorî vê yekê, standardek IEEE ji bo gas-insulated switchgear later developed û li gorî sal 2019 official published. Standardek ji bozî IEC standards hatine çêkerandin, lê li gorî parametreyan, construction, û testing requirements li ser IEEE C37.20.2 û other relevant IEEE standards, particularly to meet IEEE’s safety requirements for equipment were modified.

1.Şertên Çevreser

a) Temperatûra operasyonî: maximum +40 °C; average over 24 hours not exceeding +35 °C; minimum –5 °C.
b) Altitude: not exceeding 3,300 feet (1,000 meters).
c) Enclosure protection rating: NEMA 250 Type 1 (IP20) for indoor use; Type 3R (IP24) for outdoor use.

Li gorî GB/T 11022, indoor switchgear in China is classified into three minimum ambient temperature categories: –5 °C, –15 °C, and –25 °C. The minimum operating temperature specified in IEEE C37.20.9 for gas-insulated switchgear (–5 °C) is higher than that specified in IEEE C37.20.2 for air-insulated switchgear (–30 °C). Therefore, gas-insulated switchgear compliant with Chinese standards can fully satisfy the environmental requirements of IEEE C37.20.9.

Table 1 below shows the IEEE C37.20.9 requirements for rated voltage, power-frequency withstand voltage, and lightning impulse withstand voltage for gas-insulated switchgear.

Table 1 – Insulation Voltage Ratings for Gas-Insulated Switchgear per IEEE C37.20.9

Dahîna dana rastînê ya standartên Amerîkayê ji wan ên Çînê re çalak e. Bibeji bo hûn dikarin gas-insulated switchgear (GIS) li ser pîvanên rated power-frequency withstand voltage û rated lightning impulse withstand voltage yê nîşaneyên IEEE-yan be parêz bike. Mînak, kabinetek GIS 12 kV yên di standardên Çîn de çêkirin tenha bi rêyên testa dielectric ên voltage class 4.76 kV da li ser standardên Amerîkayê dest pê kirin, herêmî kabinetek GIS 24 kV yên Çîn bi rêyên insulation ên voltage classes derbasdar û jêr 27 kV.

IEEE Std 386™-2016 pîvanên ji bo connectors insulated separable yên bikar an li ser systems distribution yên rated from 2.5 kV to 35 kV—herêmî "American-style elbow connector" standard name kirin—nîşan dide. Ev connectors guhertin bûn li ser equipment-ên Amerîkayî waney pad-mounted transformers û cable distribution boxes. Berbendî, gas-insulated switchgear-ê Çînî xebit û plugs conforming to EN 50181 bikar an. Standarda IEEE ji bo gas-insulated switchgear pîvanên specific dielectric test ji bo various types of cable termination accessories nîşan dide.

2 Rated Current
Valoyên recommended ji bo rated continuous current of main busbars in IEEE gas-insulated switchgear (MEGIS) 200 A, 600 A, 1200 A, 2000 A, 2500 A, 3000 A, û 4000 A ne—ji ratings common Çînî waney 630 A, 1250 A, û 3150 A ve çalak e.

3 Rated Frequency
Standarda IEEE rated frequency 60 Hz nîşan dide, herêmî standarda frequency în Çîn 50 Hz e. Frequency 60 Hz higher tenha impact significant bi temperature rise û short-circuit breaking performance re heye. Li ser GB/T 11022, ji bo switchgear û controlgear rated at either 50 Hz or 60 Hz—provided there are no ferromagnetic components near current-carrying parts—if the measured temperature rise during a continuous current test at 50 Hz does not exceed 95% of the maximum allowable limit, the equipment is considered compliant for both frequencies, i.e., it also meets the 60 Hz temperature rise requirement.

Berbendî, li ser limited heat dissipation in gas-insulated switchgear û its relatively small thermal margin, design improvements often necessary ne bi satisfy 60 Hz requirements. Products that have passed the 1.1× rated current temperature rise test under Chinese standards can generally meet the 60 Hz requirement.

4 Rated Short-Time Withstand Current and Rated Peak Withstand Current
Valoyên recommended ji bo short-time withstand current of IEEE gas-insulated switchgear di Table 3 de nîşan dayin. Ji bo standardên Çînî, ku short-circuit duration 3 s or 4 s define kirin, standarda IEEE short-circuit duration 2 seconds define kirin.

Furthermore, because the IEEE system operates at 60 Hz (as opposed to 50 Hz), the rated peak withstand current is defined as 2.6 times the rated short-time withstand current. For example, a rated short-time withstand current of 31.5 kA corresponds to a rated peak withstand current of 82 kA—slightly higher than the typical 80 kA used in China. To withstand the electrodynamic forces generated by such peak short-circuit currents, contact pressure and mechanical strength of components such as contacts must be enhanced.

Table 2 – Recommended Short-Time Withstand Current Ratings for IEEE Gas-Insulated Switchgear