Atmospheric Pressure Fully Sealed Air Insulated RMU (up to 12kV)

Distribution switchgear with hermetically sealed pressure system

Atmospheric pressure fully sealed air insulated RMU features air insulation and vacuum interruption. The main electric circuit is sealed in the RMU cabinet which adopts atmospheric pressure air as the insulation medium. The RMU’s high reliability and zero carbon emission are unprecedented in the field of power distribution networks. Over 10 years of its safe and stable application at home and abroad has proved that the switchgear is the right choice for those who want high reliable electricity supply and a greener environment.

Advantages Safety Guarantee
Equipment safety
The atmospheric pressure fully sealed air insulated RMU is designed to work for 40 years in even tough environments. Since 2010, more than 40,000 of our RMUs worldwide have been running without trouble.
Personnel Safety
The single-phase insulating and multi-time safety margin eliminates risks of internal arcing. The conductive part outside or inside the RMU cabinet is fully earthed.
Reliable Performance
The simple, compact and reliable circuit breaker and the three-position disconnecting/earthing switch are respectively installed outside the RMU cabinet. Their mechanical endurance respectively goes up to 10,000 and 3,000 cycles. Pursuing Green Development with Zero Carbon Emission

The RMU follows the trend of green development to mitigate global warming by employing air as insulating medium. 95% of its components are recyclable.

High Operation and Maintenance Efficiency

The RMU can be equipped with smart measurement and control components to realize measurement digitalization, control networking, state visualization and information interaction, boosting operation and maintenance efficiency in line with the future smart power grid.

Adaptation to Various Scenarios

The RMU only takes one forth of the KYN-type switchgear’s occupying area and can be mounted against the wall, which substantially reduces the switch room’s or outdoor enclosure’s floor area and space occupation and finally lowers installation costs.

Features Design & Development Eco-friendliness—SF6-free vacuum interrupter and air insulation system in the RMU; Personnel Safety—the single-phase insulating and self-healing system avoids internal arcing explosion; Superior Insulation Performance—the atmospheric pressure sealed air insulated enclosure prevents the insulation performance from being weakened by pressure leak within the service life; Intelligent Function—multiple smart sensors like wireless temperature sensors and partial discharge testing sensors can be installed in the RMU to realize automatic equipment monitoring; Forward-looking Design—the RMU is a primary device in a smart power grid with full-range fixed-type circuit breaker, to provide a solution for power distribution network building; Modular Design—the small size and compact structure of the RMU makes its operation and maintenance easy. Appearance & Structure Standard extension of being extensible at both sides; Flexible combinations to meet customers’ diverse power distribution demands; Small size on a par with SF6 gas switchgear; Operation mechanism designed by SCR concepts: simple, compact, reliable; Lower three-position disconnecting switch structure to make disconnection and earthing conditions visible. Overall Dimension 1-bay 2-bay 3-bay

Unit	Length (mm)	Width (mm)	Height (mm)
1-bay	460	770	1620
2-bay	810	770	1620
3-bay	1160	770	1620

Differences among 1-bay, 2-bay and 3-bay
Structure
the difference depends on whether the primary conductive part shared an enclosure.
Function
2-bay equals a combination of two 1-bays, and 3-bay equals three 1-bays or one 1-bay and one 2-bay.
Size
2-bay is slightly smaller than a combination of two 1-bays, and 3-bay smaller than three 1-bays or one 1-bay and one 2-bay.
Price
1-bay is more costly compared with 2-bay or 3-bay evenly. Installation Demonstrations Applications The atmospheric pressure fully sealed air insulated RMU can be applied in scenarios requiring high power supply reliability, such as airports, government buildings, ports, hospitals, data centers, commercial properties and transportation system. Thanks to its small size and maintenance-free system, the RMU can be deployed in remote sites which demand more maintenance labour; The atmospheric pressure fully sealed air insulated RMU can also be transformed into street light box which supplies electricity to street lamps and stands as street decoration as night falls. Previous Next

Item			Unit	Parameter
Rated Pressure (Ur)			kV	12/17.5
Rated Frequency (Fr)			Hz	50/60
Rated Current (Ir)			A	630
Rated Insulation Level	Short-time Power-frequency Withstand Voltage (Ud)		kV	42/48
	Lightning Impulse Withstand Voltage (Up)		kV	75/85
Rated Short-time Withstand Current (Ik)			kA	20/25
Rated Short-circuit Duration（tk）			S	4
Rated Peak Withstand Current（Ip）			kA	50/63
Rated Short-circuit Breaking Current (Isc)			kA	20/25
Rated Short-circuit Making Current (Ima)		Vacuum interrupter	kA	50/63
		Earthing switch
Auxiliary Circuit and Control Circuit		Rated Pressure (Ua) DC/AC	V	≤400
		Power-frequency Withstand Voltage (1min)	V	2000
Mechanical Endurance		Circuit breaker	cycle	10000
		Disconnecting switch	cycle	3000
		Earthing switch	cycle	3000
Electrical Endurance		Circuit breaker	rating	E2
		Earthing switch	rating	E2
Degree of Protection by Enclosure				IP4X
Degree of Protection by Fully Sealed Tank				IP65

Normal Service Conditions

Maximum temperature	40℃ (average temperature ≤35℃ within 24h)
Minimum temperature	-25℃
Altitude	≤2000m
Daily average relative humidity	≤95%
Monthly average relative humidity	≤90%

Special Service Conditions

Provided the equipment should be run in special and harsh environment, please consult our experts.

Vacuum Circuit Breaker Disconnecting Switch / Earthing Switch Inspection Window of Disconnection/Earthing Status Protection Terminal Cable Compartment Fundamental Units

Smart Ring series with following medium-voltage module function:

D (cable connection unit) B (circuit breaker unit) BB (circuit-breaker shared enclosure unit) BBB (circuit-breaker shared enclosure unit) M (medium-voltage metering unit) PTX (PT unit) BS (busbar sectionliser unit) PT (PT unit) PT (PT unit) PTB (PT unit)

Note: "←" and "→" in the diagram are expandable kits.

Flexible combination can be customized as request. Please consult the manufacturer if you have any question.

SRL-610 Series Microcomputer Integrated Protection Device Multiple protection methods of three-section over-current protection, earthing protection, non-power protection and over-load protection, enhancing anti-interference capability and reduce power consumption; Multiple intelligent switch input circuit supporting free user presetting; Microcomputer protection devices of other brands can be equipped as request. IPS/IPC series Single-phase Earth Fault Detector High sensitivity underpinned by phase asymmetry algorithm, leading to the minimum detectable fault current to be 0.5A; Effectively detecting high impedance earth fault with up to 12,000Ω earth resistance; Simple and easy installation which only needs to sample three-phase current without using zero-sequence CT, PT and other equipment; Suitable for systems with small resistance earthing, isolated neutral point or Petersen coil grounding. Condensing/heating Dehumidification Device

Reducing water vapor in the working environment to ensure effective and safe machine operation

Wireless Temperature Sensor

Real-time testing of cable top’s temperature and making alarms for faults in advance

Partial Discharge Testing Device

Tracking partial discharge and display the testing outcome simultaneously

Applicable Standards IEC 62271-200 Part 200 High-voltage Switchgear and Controlgear: 1kV~52kV AC Metal Fully-sealed Switchgear and Controlgear IEC 62271-100 Part 100 High-voltage Switchgear and Controlgear: High-voltage AC Circuit-breaker IEC 62271-1 Part 1 High-voltage Switchgear and Controlgear: General Specifications More About Air Insulated RMU How does the RMU ensures safe and reliable operation?

A:
First, the atmospheric pressure fully sealed system shields the RMU from external effects and guarantees the stable operation. Second, the switchgear’s single-phase insulating interior eliminates risks of internal arcing explosion. Third, the insulating medium inside the cabinet is air of atmospheric pressure which prevents the insulation performance from being weakened by pressure leak during the service life.

How is the acceptance of the RMU in China?

A:
In 2017, the atmospheric-pressure sealed air insulated switchgear was included in the purchasing list of State Grid Corporation of China and China Southern Power Grid which are ranking 3rd and 89th respectively 2022 list. Since then, the RMU has been bought in abundance every year by the two Chinese power grid giants whose services cover almost all over China.

What is the installation requirement?

A:
The RMU can be mounted against wall and 80cm of space should be preserved in front of the cabinet for installation. The switchgear adopts lower incoming and lower outing of cable. Please contact us if you prefer other installation methods.

Is there any possibility of combining the HM POWER’s RMU with other brands’ switchgear?

A:
Combining switchgears of different brands is not advised, as they vary in plug and circuit and combining them may result in risks.

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atmospheric pressure fully sealed air insulated switchgear Ring Main Unit Manufacturer

As a trusted manufacturer of ring main unit (RMU), HM POWER offers high quality atmospheric pressure fully sealed air-insulated switchgears and reliable solutions for the smart grid power distribution industry. Our state-of-the-art technology and experienced team of experts ensure that our RMUs meet the highest standards of performance, reliability and safety.