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  • SF6 Gas Ring Main Unit (GRMU)

SF6 Gas Ring Main Unit (GRMU)

SF6 Gas Ring Main Unit (GRMU)

Entec's SF6 Gas Insulated Ring Main Unit is designed for application in underground lines for voltage classes of 17.5kV and 24kV. It consists of Load Break Switch(LBS) and Circuit Breaker(CB) or Fuse-switch modules, and this combination is variable depending on customer's requirements.

The operating mechanism is spring charged for CB with vacuum interrupters and spring toggle for SW and fuse-switch. A minimum number of parts for mechanism allows long lifetime service resulting cost effectiveness.

The internal part of Gas RMU is completely insulated with SF6 Gas and protected by a stainless steel enclosure.

The Gas RMU can be operated as a manual type using ETR20H Self-Powered Protection Relay or as an automatic/motorized type using ETR304/306 multi-circuit relay that is capable of metering, monitoring, recording, and communication.

The Gas RMU has been fully type tested by accredited laboratories such as CESI and KERI according to the international standard IEC 62271-100,102,103 and 200.

Maintenance Free
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  • Minimum number of mechanism part allows long life time service with cost effectiveness
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  • Fully enclosed housing prevents the operating units from environmental influences
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  • Separate main switch and earthing switch with safety interlockt
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  • Dual protection by Earthing switch with disconnector during maintenance
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  • Gas rupture disk installed to prevent damage by gas explosion
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  • Low rate of gas leakage below 0.1% for 30 years
Operation Safety
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  • Separate main switch and Earthing Switch with safety interlock
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  • Dual protection by Earthing Switch with Disconnector during maintenance
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  • Gas rupture disk installed to prevent damage by gas explosion
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  • Low rate of gas leakage below 0.1% for 30 years
Advanced Reliability of Operation
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  • 2,000 times of operation guaranteed
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  • Manual / Automatic operation available
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  • Remote and local operation available via SCADA system
Other Technical Features
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  • Live line status indicator on each circuit for safety
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  • Contact status indication through mimic diagram
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  • “T” elbow connector (Plug-in type) for high voltage cable connection
Electrical ratings
Description
Rated maximum voltage [kV] 17.5 24
Rated current [A] 630 630
Operation manual, automatic manual, automatic
Frequency [Hz] 50 / 60 50 / 60
Power frequency withstand voltage [kV] 50 50
Basic impulse withstand voltage [kV] 110 125
Pressure of SF6 gas for insulation Nominal: 0.14 MPa Nominal: 0.13 MPa
Minimum: 0.11 MPa Minimum: 0.10 MPa
International standard IEC 62271-1, IEC 62271-100/102/103, IEC 62271-200
Load Break Switch
Mainly active load current [A] 630 630
Cable charging current [A] 10 40
Short time withstand current, 3sec [kA] 21 16
Short circuit making current [kA] 54.6 40
Circuit Breaker
Cable charging breaking current [A] 31.5 40
Short circuit breaking current [kA] 21 / 3sec 16 / 1sec
Short time withstand current [kA] 21 / 3sec 16 / 1sec
Short circuit making current [kA] 54.6 40