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Environmentally Friendly Gas-Insulated Ring Main Unit Equipment

Environmentally Friendly Gas-Insulated Ring Main Unit Equipment

The UN0-12, 24/630-25kA environmentally friendly gas-insulated ring main unit is a fully sealed and fully insulated ring main unit that employs advanced vacuum interrupter technology. From the design perspective, it meets environmental requirements by being oil-free and SF6-free. All conductive parts inside the switchgear are housed in a sealed stainless steel enclosure, with dry air serving as the primary insulating medium within the enclosure. The main switch uses a vacuum arc-extinguishing system, while the isolating switch features a three-position structure. The enclosure boasts an IP67 protection rating, making it immune to the effects of condensation, frost, salt spray, pollution, corrosion, ultraviolet radiation, and other similar factors.

Product Features


· This product is designed and manufactured in compliance with GB and IEC standards.
· Manufactured with a structural design featuring vacuum arc extinction and all-insulated environmentally friendly gas.
· The air box achieves an IP67 protection rating and remains free of leaks or the need for refilling/adding air throughout its installation process and service life.
· The product meets requirements for altitudes of 5,000 meters and below.
· Suitable for operation in environments with industrial pollution, salt spray, and high humidity; meets C3 standards on land and C4 standards at sea.

Applicable Locations


10. Offshore and onshore wind power substations for 20kV voltage networks;
10. Energy storage and photovoltaic box-type substations for 20kV voltage grid integration;
10. Ring main units for step-up or step-down voltage transformation and distribution in 20kV networks.

Main uses and scope of application (including, if necessary, the scope of non-application)


Widely used in distribution substations and packaged substations located at load centers such as urban residential communities, high-rise buildings, large public buildings, and industrial enterprises.

Specifications


Ring main units come in two types: individual-unit designs and common-cabinet designs. Among the individual-unit designs, there are four categories: load switch cabinets, isolating PT cabinets, and circuit breaker cabinets.
·Upper isolator, lower circuit breaker cabinet
·Upper circuit breaker, lower isolating switchgear
·Isolation PT cabinet (PT)
·Load switchgear

Technical Specifications


Operating continuity levels defined in GB/T 3906

Other high-voltage compartments or functional units remain energized.

LSC 1: Lower service continuity

LSC 1 LSC 2

LSC 2: Higher Service Continuity

●

Partition between compartments

PI: Insulating partition

PI PM

PM: Metal Grounding Baffle

●

Insulation and Switching

Main circuit disconnection

Vacuum circuit breaker

Interrupting medium

Vacuum arc-extinguishing chamber

Insulating medium

Dry air

Relative inflation pressure

Rated inflation pressure (gauge pressure at 20℃)

MPa

0.04

Minimum inflation pressure (gauge pressure at 20℃)

MPa

0.02

Annual relative leakage rate of gas

%/year

≤0.01

Insulation level

Rated voltage

kV

12/24

Rated frequency

Hertz

50

Rated insulation level

Power-frequency withstand voltage (phase-to-phase, phase-to-ground, vacuum interrupter contacts)

kV

42/65

Power-frequency withstand voltage (isolated break)

kV

48/79

Power-frequency withstand voltage (auxiliary and control circuits)

kV

2

Lightning impulse withstand voltage (phase-to-phase, phase-to-ground, vacuum interrupter)

kV

75/125

Lightning Impulse Withstand Voltage (Isolation Break)

kV

85/145

Current level

Rated current—busbar

A

630

Rated short-circuit breaking current

kA

25

Rated short-circuit making current (main switch/grounding switch)

kA

63/63

Short-time withstand current and duration (main circuit + earthing switch, earthing connection)

kA/s

25/4 . 21.75/2

Rated peak withstand current (main circuit + earthing switch, earthing connection)

kA

63/54.81

Internal arc fault withstand capability

Grade A

AFLR front, side, and rear

kA

20

Duration

S

0.5

Enclosure protection rating

Complies with GB/T4208 standard enclosure protection.

An energized electrical box

IP67

Cable Room

IP43

Institutional Room

IP4X

Low-pressure room

IP4X

Mechanical impact protection rating

Grade compliant with GB/T 20138

IK07

Other features

Expected service life

Year

30

Busbar/grounding busbar (copper bar)

120 mm²