The Air-Insulated Ring Main Unit (RMU) is a compact, reliable, and maintenance-friendly switchgear solution designed for medium-voltage (MV) distribution networks. Featuring an inflatable cabinet for enhanced insulation and an open-type current transformer (CT), this RMU ensures efficient power distribution, protection, and monitoring in utility, industrial, and commercial applications.
The open-type current transformer (CT) used in an air-insulated Ring Main Unit (RMU) inflatable cabinet, the main technical parameters typically include:
1. Rated Primary Current (Ipn)
- Standard values: 100A, 200A, 400A, 630A, 800A, 1250A, etc.
2. Rated Secondary Current (Isn)
- Typically **1A or 5A** (common for protection & metering).
3. Accuracy Class
- Metering:0.2, 0.5, 0.5S, 1.0
- Protection:5P, 10P** (with associated accuracy limit factor, e.g., 5P10, 10P15).
4. Burden (VA)
- Common values: **2.5VA, 5VA, 10VA, 15VA** (depends on application).
5. Rated Frequency
- **50Hz or 60Hz** (as per grid standard).
6. Rated Short-Time Thermal Current (Ith)
- Typically:10kA, 20kA, 25kA (1s or 3s)
7. Rated Dynamic Current (Idyn)
- Usually **2.5 × Ith** (e.g., 50kA peak for 20kA thermal rating).
8. Insulation Level
- 0.72/3/-kV
LMZK-10-2 Inflatable cabinet open type current transformer
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Single-phase voltage transformer (VT) with a fuse link is a key component used in Ring Main Units (RMUs) and switchgear systems. It is designed to step down high voltage to a safe, measurable level for metering, protection, and control purposes. The integrated fuse link provides over current protection, safeguarding the transformer and connected equipment from fault conditions.
Key Features:
- Single-phase design for compact RMU installations.
- High accuracy for metering & protection (typically 0.5/3P class).
- Fuse link protection against short circuits & overloads.
- Insulation: Dry-type or resin-encapsulated for durability.
- Primary & secondary terminals for easy connection.
- Lightweight & maintenance-free construction.
- Compliance with IEC/ANSI standards for reliability.
Functions:
1. Voltage Step-Down: Converts high voltage (e.g., 11kV, 22kV) to low voltage (110V, 220V) for safe measurement.
2. Metering: Supplies accurate voltage signals to energy meters & monitoring devices.
3. Protection:Feeds voltage signals to relays for fault detection (e.g., over/under voltage).
4. Fuse Protection: Prevents damage due to short circuits or excessive current.
5. Control Circuit Powering:** Provides voltage for automation & control systems in RMUs.
Applications:
- Ring Main Units (RMUs)
- Switchgear panels
- Distribution substations
- Industrial power systems
Three-phase combined current and voltage transformer (metering unit) is an essential component in medium-voltage (MV) switchgear, RMUs (Ring Main Units), and substations.
It integrates current and voltage transformation, protection, and metering functions in a single compact unit.
These transformers are designed for high accuracy, reliability, and safety in electrical distribution systems.
Applications:
- Ring Main Units (RMUs)
- Switchgear Panels
- Substations (MV/HV)
- Industrial Power Distribution
- Renewable Energy Systems (Solar/Wind Farms)
A three-phase five-limb voltage transformer (VT) is a specialized instrument transformer designed for gas-insulated switchgear (GIS) and compact RMU applications. It provides high-precision voltage measurement, protection, and control in medium-voltage (MV) and high-voltage (HV) systems. The five-limb core design ensures superior magnetic performance, reducing errors and improving stability under unbalanced conditions.
Functions & Applications
Primary Functions
Voltage Transformation - Steps down HV/MV to safe levels for metering & control.
Energy Measurement- Feeds precision signals to smart meters & SCADA systems.
Protection Relaying - Supports overvoltage, undervoltage, and earth fault protection.
Grid Synchronization - Ensures safe paralleling of power sources.
Power Quality Monitoring - Detects harmonics and voltage fluctuations.
Typical Applications
- Gas-Insulated Switchgear (GIS)
- Compact RMUs & AIS (Air-Insulated Substations)
- Wind & Solar Power Plants
- Railway Electrification Systems
- Industrial HV Distribution Networks
APPLICATION
1. Question : Why choose us and trust us?
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Management concept: Pursuing excellent quality, creating first-rate services
2. Question : Where is your factory located ? How can I visit there ?
Answer: With an ISO90001 certified factory located in Yueqing city, Zhejiang Province, P.R.OF China.
It takes about 4 hours from SHANGHAI by high-speed rail and 45 minute by air.
It is very pleasure for all to visit us.
3. Question : Can you do OEM ?
Answer: Yes, we have the ability to do OEM /ODM to meet your requirements.
4. Question : What is the payment terms?
Answer: In general T/T, L/C, Paypal or others we can discuss.
5. Question :How about the delivery time?
Answer: Usually, if have enough in warehouse, the delivery time is within 3 working days.
If need produce, the lead time is about 10-20 working days according to quantity of the order.
6. Question : How about the shipping method?
Answer: For sample or small order, deliver by International express, such as DHL, FEDEX, TNT, UPS, EMS and so on.
For large order, deliver by sea or by air according to buyers shipping instructions.
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