RMU (Ring Main Unit) is a compact, factory-assembled, and metal-enclosed switchgear unit used in medium-voltage power distribution (typically 11kV to 33kV).
Technical Specifications
|
Feature
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Specification
|
|
Rated Voltage
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11kV / 22kV / 33kV
|
|
Frequency
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50 Hz
|
|
Rated Current
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Upto 1250A
|
|
Short-Circuit Capacity
|
20kA Or 21kA for 3 seconds
|
|
Protection Class
|
IP54 | IP55 | IP67
|
|
Phase Configuration
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3-Phase, 3-Wire
|
|
Breaking Capacity
|
52.5 kA
|
|
Insulation Level
|
SF6 Gas
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Design Features
§ Configuration:
Available in extensible and non-extensible designs, with common configurations including 2-way, 3-way (e.g., 2 load break switches + 1 circuit breaker), and 4-way units.
§ Switching Devices:
Include load break switches (LBS) and circuit breakers (CB), often with integrated earthing switches for safety.
§ Operation:
Can be operated manually or with a motorized mechanism for remote control/SCADA integration.
§ Safety:
Key safety features include mechanical interlocks to prevent hazardous operations, a pressure-release device in case of internal fault, and live cable indicators.
§ Maintenance:
Designed to be largely maintenance-free, with the sealed-for-life gas tank ensuring no gas handling is required for up to 30 years.
§ Dimensions:
The compact design is a key feature; a typical 3-function unit might have dimensions around 1810mm (H) x 780mm (W) x 885mm (D).
Standard Tests
§ IEC-62271-200, IEC-61439
§ CPRI Type Tested(S/C, Temp Rise, IP)
§ Internal Arc Tested
Brands
§ Novatric Export
Common Applications
§ Industries & Manufacturing | Infrastructure & Utility | Commercial | Renewable Energy | Telecom