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NRTs-40.5 40.5kV SF6 Gas Insulated Ring Main Unit

NRTs-40.5 SF6 Gas Insulated Switchgear
NRTs-40.5 SF6 Gas Insulated Switchgear

NRTs-40.5 40.5kV SF6 Gas Insulated Ring Main Unit

The NRTs-40.5 is a 40.5kV SF6 gas-insulated ring main unit (RMU) developed by NATUS Electric for medium- and high-voltage power distribution applications. It features an IP67-rated 304 stainless-steel gas tank, IAC 25 kA/1 s internal arc protection, intelligent condition monitoring, and flexible top or side expansion. These features support compact power distribution configurations for substations, industrial facilities, and renewable energy projects, subject to the project’s electrical ratings and operating requirements.

Health Management
Full-Lifecycle Intelligent
Modular Flexible Expansion
Extreme Environment Adaptability
IAC 25 kA/1 s Internal Arc Protection
IP67 Fully Sealed Stainless-Steel Gas Tank
Model:NRTs-40.5
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Key Benefits of NRTs-40.5 SF6 Gas Insulated Ring Main Unit

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IP67 Fully Sealed Stainless-Steel Gas Tank

The 40.5kV SF6 Gas Insulated RMU adopts a 304 stainless-steel laser-welded gas tank with an annual leakage rate ≤0.25‰. The fully sealed design provides excellent resistance to condensation, salt mist, corrosion, and UV aging, ensuring long-term reliable GIS operation.

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IAC 25 kA/1 s Internal Arc Protection
The NRTs-40.5 40.5kV SF6 gas insulated RMU features a dedicated pressure relief channel and has passed the 25 kA/1 s internal arc fault test. Its internal arc protection design helps protect operators and equipment during abnormal operating conditions. The tested safety structure supports reliable operation of SF6 gas insulated switchgear in medium-voltage power distribution systems, substations, industrial facilities, and renewable energy applications.
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Full-Lifecycle Intelligent Health Management
The NRTs-40.5 40.5kV SF6 gas insulated RMU integrates five online monitoring functions: partial discharge, mechanical characteristics, contact temperature, temperature and humidity, and video recognition. This intelligent RMU supports real-time condition monitoring and reliable medium-voltage power distribution.
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Modular Flexible Expansion
The NRTs-40.5 40.5kV SF6 RMU supports top and side expansion, with a standardized 450 mm expansion width and reserved interfaces. Its modular design enables flexible configuration and future expansion of medium-voltage power distribution systems.

Product Overview

NRTs-40.5 kV is a 40.5 kV SF6 gas insulated ring main unit developed by NATUS Electric for medium- and high-voltage distribution systems.
The SF6 gas insulated ring main unit uses a high-quality stainless-steel gas tank manufactured by laser cutting and automatic robotic welding. After vacuum pumping and leak testing, SF6 insulating gas is filled into the tank, fully sealing all high-voltage live components such as the circuit breaker, load break switch and busbar. The gas tank reaches IP67 protection and is not affected by external environmental factors. It integrates a Distribution Terminal Unit (DTU) bay unit and a full-lifecycle health management system, supporting remote measurement and control, fault diagnosis and intelligent operation and maintenance. The 40.5kV SF6 Gas Insulated RMU fully complies with GB/T 3906, IEC 62271 and other domestic and international standards, and is widely used in substations, renewable energy, petrochemical, industrial and other medium- and high-voltage distribution scenarios.
40.5kV SF6 Gas Insulated RMU

NRTs-40.5 kV SF6 Gas Insulated Ring Main Unit Structure

SF6 Gas Insulated Switchgear
The cable compartment can only be opened when the feeder is isolated or earthed. The bushing complies with the DIN EN 50181 standard, features an M16 bolt connection, and the surge arrester can be connected behind the T-type cable joint.
The integrated current transformer (CT) is located on the bushing side, facilitating easy cable installation and being unaffected by external forces. The height from the bushing installation position to the ground is more than 690mm.
NRTs-40.5 kV SF6 Gas Insulated Ring Main Unit

Technical Advantages

01.
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Highly Reliable Arc Extinguishing and Operating Mechanism
The 40.5kV SF6 Gas Insulated Ring Main Unit features a highly reliable circuit breaker unit with a mechanical life of 10,000 operations, while the disconnector and earthing switch achieve 5,000 operations. The stable spring operating mechanism supports both electric and manual operation, ensuring reliable opening and closing performance under demanding operating conditions.
02.
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Extreme Environment Adaptability
The SF6 Gas Insulated Ring Main Unit is designed for harsh environments with an operating temperature range from -45°C to +75°C, humidity ≤95%, and altitude ≤2000 m. The stainless-steel gas tank and anti-corrosion coating provide excellent resistance to severe cold, high temperature, high altitude, and salt-mist environments.
03.
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Modular Bi-Directional Expansion Technology
The 40.5kV SF6 RMU supports both top and side expansion with a unified single-unit expansion width of 450 mm. Standard units can be flexibly combined into different main connection schemes, while future capacity expansion can be completed without power outage reconstruction, protecting the initial investment.

Technical Specifications

Circuit Breaker Unit


Basic Parameters
Rated VoltagekV40.5
Power Frequency Withstand VoltagekV95/118
Lightning Impulse Withstand VoltagekV190/220
Rated CurrentA630
Rated Short-Circuit Breaking CurrentkA20(25)
Rated Short-Circuit Making CurrentkA50(63)
Rated Short-Time Withstand CurrentkA/s20(4) / 25(4)
Mechanical LifeTimeCircuit Breaker: 10,000 / Isolation: 5,000 / Earthing: 5,000



Load Switch Unit


Basic Parameters
Rated VoltagekV40.5
Power Frequency Withstand VoltagekV95/118
Lightning Impulse Withstand VoltagekV190/220
Rated CurrentA630
Rated Short-Circuit Breaking CurrentkA20(25)
Rated Short-Circuit Making CurrentkA50(63)
Rated Short-Time Withstand CurrentkA/s20(4) / 25(4)
Mechanical LifeTimeCircuit Breaker: 10,000 / Isolation: 5,000 / Earthing: 5,000



Circuit Breaker Unit (Busbar Grounding)


Basic Parameters
Rated VoltagekV40.5
Power Frequency Withstand VoltagekV95/118
Lightning Impulse Withstand VoltagekV190/220
Rated CurrentA630
Rated Peak CurrentkA50(63)
Rated Short-Time Withstand CurrentkA/s20(4) / 25(4)
Mechanical LifeTimeLoad: 5,000 / Earthing: 5,000



Commonly Used Standards


Basic Parameters
IEC 62271-200:2011High-voltage switchgear and controlgear - Part 200: AC metal-enclosed switchgear and controlgear for rated voltages above 1kV and up to and including 52kV
GB/T 3906-20063.6kV~40.5 kV AC metal-enclosed switchgear and controlgear
GB/T 11022-2011Common specifications for high-voltage switchgear and controlgear standards
GB/T 1984-2014High-voltage alternating-current circuit breakers
GB/T 3804-2017High-voltage alternating-current switches for rated voltage above 3.6kV and less than 40.5 kV
GB/T 1985-2014High-voltage alternating-current disconnectors and earthing switches
IEC 62271-105High-voltage switchgear and controlgear - Alternating-current switch-fuse combinations
IEC 62271-103High-voltage switchgear and controlgear - Switches for rated voltages above 1kV and up to and including 52kV
IEC 60265-1High-voltage switches - Part 1: Switches for rated voltages above 1kV and less than 52kV
DL/T 404-2018AC metal-enclosed switchgear and controlgear
DL/T 593-2016Common specifications for high-voltage switchgear and controlgear standards



General Characteristics


Basic Parameters
Altitude≤ 2000 m
Ambient temperature-25°C to +40°C
Daily average temperature≤ 35°C
Relative humidityDaily average ≤95%; monthly average ≤90%
Pollution degreeII / Ⅲ / Ⅳ (as required by project conditions)
Installation locationIndoor, free from severe vibration, corrosive gas and conductive dust



Operating Conditions


Basic Parameters
Ambient air temperatureMaximum: +40°C; minimum: -25°C; average over 24h: ≤35°C
HumidityDaily average relative humidity ≤95%; monthly average relative humidity ≤90%
Altitude≤ 2000 m
Installation environmentIndoor installation; no obvious vibration, no corrosive or explosive gas, and no severe dust pollution
Seismic intensitySuitable for normal substation operating environment



Cabinet Construction Method


Basic Parameters
Top-Expansion Cabinet Combination MethodCabinets are combined through the top-expansion interface to realize busbar extension and cabinet-to-cabinet connection.
Side-Expansion Cabinet Combination MethodCabinets are combined through the side-expansion interface to support flexible line-up configuration.

Application
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石油石化
工业行业
市政商业

NRTs-40.5 kV SF6 Gas Insulated Ring Main Unit FAQ

Yes. The 40.5kV SF6 gas insulated RMU uses a 304 stainless-steel laser-welded gas tank with helium mass spectrometry leak detection and a 24-hour, 0.3 bar underwater immersion test. The gas tank reaches IP67 protection, helping prevent dust and water ingress.
Yes. The NRTs-40.5 SF6 gas insulated ring main unit is designed for an operating temperature range of -45°C to +75°C. An intelligent heating and dehumidification system helps maintain reliable operation in extreme low-temperature environments.
The NRTs-40.5 40.5kV SF6 RMU supports both top and side expansion, with a standardized 450 mm expansion width per unit. Its modular design allows additional units to be added for future capacity expansion without major reconstruction.
A 40.5kV gas insulated ring main unit (RMU) is a medium-voltage power distribution assembly that encloses key electrical components in a sealed, gas-insulated compartment. The NATUS NRTs-40.5 uses SF6 gas insulation and an IP67-rated stainless-steel gas tank. Its configuration and ratings should be selected according to the project's electrical requirements, protection scheme, and operating environment.
The NRTs-40.5 intelligent RMU integrates five online monitoring functions: in-cabinet partial discharge detection, mechanical characteristic detection, contact temperature monitoring, temperature and humidity control, and video recognition. These functions support real-time medium-voltage switchgear condition monitoring and fault warning.
The annual SF6 gas leakage rate is ≤0.25‰. Under normal operating conditions, the sealed SF6 gas insulated switchgear is designed to operate without gas replenishment for up to 30 years, reducing routine maintenance requirements.
Yes. The NRTs-40.5 SF6 gas insulated RMU is equipped with a standard DTU bay unit and supports standard communication protocols. It can connect with distribution automation and SCADA systems for remote monitoring and control.
The SF6 Gas Insulated Ring Main Unit has passed the 25 kA/1 s internal arc fault test. A built-in dedicated pressure relief channel directs fault arc energy outside the cabinet; the cabinet door does not burst open, providing personnel protection.

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