High-Voltage Ring Main Unit (RMU)
Zhejiang Tianrun Electric Co., Ltd. is one of the leading manufacturers and suppliers of high-voltage ring main unit (rmu) in China. We are committed to providing high quality customized products with competitive price. We warmly welcome you to buy bulk advanced high-voltage ring main unit (rmu) from our factory. Also, quotation is available.
Product Overview
The HXGN series box-type fixed AC metal-enclosed Ring Main Unit (RMU) - hereinafter referred to as the "RMU" - is a three-phase AC indoor complete set of distribution equipment with a rated voltage of 3.6 kV to 24 kV and a rated frequency of 50 Hz/60Hz. This Ring Main Unit is primarily used in urban distribution ring-network power supply systems, terminal distribution networks and industrial electrical installations to receive, distribute, protect and monitor electrical energy. The RMU can also be installed inside package substations as the high-voltage incoming unit.
This Ring Main Unit (RMU) series employs load-break switch–fuse combinations as the core switching elements (vacuum circuit breakers are available for selected schemes), and adopts a box-type fixed metal-enclosed structure. Featuring compact design, reliable operation, easy maintenance and outstanding cost-effectiveness, the HXGN RMU is one of the most widely applied Ring Main Unit products in the medium-voltage distribution sector.
Product Features
Box-type fixed metal-enclosed structure
High structural strength and protection, installable side by side to form ring-network systems.
Four-compartment independent metal separation
Busbar / switch / cable / instrument compartments fully isolated, fault containment with pressure relief channels for safety.
LBS–fuse combination protection
LBS switches load current, fuses handle short-circuit protection - economical and reliable.
Optional vacuum CB scheme
Rated current 1250–2500A, short-circuit breaking 20–31.5kA, suitable for frequent-operation circuits.
"Five-Prevention" mechanical interlocking
Forced interlock among LBS - earthing switch - door, eliminating five typical misoperations.
Spring-charged operating mechanism
Dual manual / electrical operation, switching speed independent of voltage fluctuation, reliable action.
Compact, modular combination
Standard unit width 375–500mm, incoming / outgoing / metering / PT / tie units freely combinable.
Air insulation, green and eco-friendly
SF6-free, no leak or recovery maintenance, low life-cycle cost.
Type Designation
Specification
|
Parameter |
Unit |
Value |
|
Rated Voltage |
kV |
3.6 / 7.2 / 12 / 15 / 17.5 / 24 |
|
Rated Frequency |
Hz |
50 /60 |
|
Main Circuit Rated Current |
A |
630 / 1250 – 2500 |
|
Rated Short-Time Withstand Current (4s) |
kA |
20 / 25 |
|
Rated Peak Withstand Current |
kA |
50 / 63 |
|
Rated Transfer Current |
A |
1600 |
|
Fuse Maximum Rated Current |
A |
125 (200 optional) |
|
LBS Rated Breaking Current |
A |
630 |
|
LBS Full-Capacity Breaking Operations |
times |
≥ 100 |
|
Mechanical Life |
times |
≥ 2000 |
|
1 min Power-Frequency Withstand Voltage (phase-earth) |
kV |
42 (12 kV class) |
|
1 min Power-Frequency Withstand Voltage (isolation gap) |
kV |
48 (12 kV class) |
|
Lightning Impulse Withstand Voltage (phase-earth) |
kV |
75 (12 kV class) |
|
Lightning Impulse Withstand Voltage (isolation gap) |
kV |
85 (12 kV class) |
|
Secondary Circuit 1 min PF Withstand Voltage |
kV |
2 |
|
Degree of Protection |
- |
Enclosure IP3X, internal compartments IP2X |
|
Operating Mechanism |
- |
Spring-charged (manual/electrical) |
|
Control Supply Voltage |
V |
AC/DC 220 / 110 |
|
Insulation Method |
- |
Air insulation |
|
Main Switching Element |
- |
LBS–fuse combination / vacuum CB (optional) |
Note: The technical parameters of our transformers are for reference only. Customized solutions are available, with specifications adjustable according to project‑specific requirements.
Environment
|
Environment Parameter |
Requirement |
|
Altitude |
Not exceeding 1000 m (high-altitude type available when exceeded) |
|
Ambient Temperature |
-25 °C to +40 °C (daily variation not exceeding 15 °C) |
|
Relative Humidity |
Daily avg. ≤ 95%, monthly avg. ≤ 90% (at +25 °C) |
|
Water Vapor Pressure |
Daily avg. ≤ 2.2 kPa, monthly avg. ≤ 1.8 kPa |
|
Seismic Intensity |
Not exceeding degree 8 |
|
Surrounding Environment |
No conductive dust, no corrosive gases, no explosion hazard |
|
Pollution Degree |
Not exceeding Class 3 (corresponds to IEC 60664-1 Pollution Degree 3) |
|
Vibration & Shock |
No severe vibration or shock, vertical inclination not exceeding 5° |
Note: Where service conditions differ from the above, they shall be agreed between the user and the manufacturer. Special environment customized products (high-altitude, anti-corrosion, high-temperature resistant, etc.) are available.
Application
- Urban ring-network supply: 10kV/11kV distribution RMU, dual-source interconnection, fault isolation, load transfer.
- Terminal distribution: End-point 10kV distribution in residential, commercial, office, hospital and school buildings.
- Industrial parks: 10kV distribution and large motor feeder control in factory workshops.
- Package substations: HV unit of European-style package substations, for space-constrained outdoor sites.
- Small substations: 10kV incoming/outgoing, metering and compensation in small/medium substations.
- Municipal infrastructure: Distribution for water/sewage plants, gas stations, heating plants, pumping stations.
- Street & landscape lighting: 10kV distribution control for urban road and landscape lighting.
- Temporary/emergency power: Temporary distribution for construction sites and exhibitions, quick assembly.
- Renewable energy grid connection: Collector line switchgear at box-type transformer HV side in PV and wind farms.
FAQ
Q1: What exactly does HXGN's "Five-Prevention" interlocking refer to?
A: "Five-Prevention" refers to preventing five typical electrical misoperations:
• Prevent incorrect opening/closing of CB (LBS);
• Prevent operating disconnector under load;
• Prevent earthing (closing earthing switch) while energized;
• Prevent closing CB (disconnector) with earthing switch closed;
• Prevent entering energized compartments.
Q2: What does protection degree IP3X mean?
A: The IP protection degree consists of two digits. The first indicates protection against solid foreign objects, the second against water.
IP3X: The first digit "3" means it can prevent solid foreign objects larger than 2.5mm in diameter from entering (such as tools, wires); the second digit "X" means no water protection test was performed (indoor equipment typically does not require water protection).
HXGN enclosure is IP3X, internal compartments are IP2X (prevents objects larger than 12.5mm, such as fingers).
Compared to IP2X, IP3X offers stronger protection, preventing smaller tools from accidentally touching live parts, with higher safety.
Q3: What are HXGN's "four compartments"? What is their function?
A: HXGN cabinet interior is divided into four independent compartments by metal partitions:
• Busbar compartment: Main busbars and branch busbars, enabling inter-cubicle electrical connection
• Switch compartment: LBS (or vacuum CB), earthing switch and other core switching elements
• Cable compartment: Cable terminals, CTs, earthing switch (some schemes), the cable connection area
• Instrument compartment (LV compartment): Relay protection devices, measuring instruments, operation buttons, terminal blocks and other secondary elements.
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