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Gas-Insulated Ring Main Units

Compact gas-insulated medium-voltage ring main units for secondary distribution networks, using SF₆ as the insulation medium and sealed gas-tank construction for switching, protection and power distribution.

Available in flexible functional configurations to suit different system voltage levels, ring feeder arrangements, transformer protection, feeder protection, metering and automation requirements.

Key Ratings

Available Rated Voltages

7.2 / 12 / 17.5 / 24 / 36 / 40.5 kV
Typical System Voltages

6 / 6.6 / 10 / 11 / 13.8 / 15 / 20 / 22 / 30 / 33 / 34.5 / 35 kV
Rated Current

630 / 1250 A
Rated Short-Time Withstand Current

Up to 25 kA
Insulation Medium

SF₆ Gas

Available Configurations

01
Load Break Switch Unit

Ring feeder switching and sectionalizing using load break switching technology.
02
Switch-Fuse Unit

Transformer feeder protection using a load-break switch and high-voltage current-limiting fuses.
03
Vacuum Circuit Breaker Unit

Incoming, outgoing and transformer feeder applications requiring vacuum interruption and protection functions, with relay protection available according to project requirements.
04
Voltage Transformer Unit

Voltage measurement, protection and monitoring, with isolating arrangements available according to project configuration.
05
Metering Panel

Instrument transformer arrangements for project metering and measurement requirements.

Technical Specifications

A. General Electrical Ratings

Rated Voltage	7.2 kV	12 kV	17.5 kV	24 kV	36 kV	40.5 kV
Typical System Voltages	6 / 6.6 kV	10 / 11 kV	13.8 / 15 kV	20 / 22 kV	30 / 33 kV	34.5 / 35 kV
Rated Frequency	50 / 60 Hz	50 / 60 Hz	50 / 60 Hz	50 / 60 Hz	50 / 60 Hz	50 / 60 Hz
Power-Frequency Withstand Voltage	20 / 23 kV	28 / 32 kV	38 / 45 kV	50 / 60 kV	70 / 80 kV	80 / 90 kV
Lightning Impulse Withstand Voltage	60 / 70 kV	75 / 85 kV	95 / 110 kV	125 / 145 kV	170 / 195 kV	185 / 215 kV

Parameter	Specification
Insulation Medium	SF₆ Gas
Degree of Protection	IP4X enclosure / IP67 gas compartment IP4X
Installation	Indoor
Applicable Standards	IEC 62271-1 / IEC 62271-200

B. Functional Unit Ratings

Parameter	Load Break Switch Unit	Switch-Fuse Unit	Vacuum Circuit Breaker Unit
Rated Current	630 / 1250 A	According to fuse-link selection	630 / 1250 A
Rated Short-Time Withstand Current	20 / 21 kA	According to configuration	25 kA
Rated Short-Circuit Breaking Current	Not applicable	According to fuse-link configuration	25 kA

Standards, Testing & Documentation

IEC-Oriented Design

Designed with reference to applicable IEC requirements and project specifications.

Factory Routine Testing

Routine tests are carried out before shipment according to product configuration.

Project Documentation

Technical datasheets, drawings and test records can be provided for project review.

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Gas-Insulated Ring Main Units

Key Ratings

Available Rated Voltages

Typical System Voltages

Rated Current

Rated Short-Time Withstand Current

Insulation Medium

Available Configurations

Load Break Switch Unit

Switch-Fuse Unit

Vacuum Circuit Breaker Unit

Voltage Transformer Unit

Metering Panel