Medium Voltage Transformers

How Does Medium Voltage (MV) Transformer Work?

Medium voltage (MV) transformers work by transforming medium level electrical voltage (typically ranging from 1 kV to 36 kV) to a lower voltage suitable for specific applications, such as powering industrial machinery, commercial buildings, or utility distribution networks. The fundamental operation is based on Faraday’ law of electromagnetic induction that involves primary and secondary coils with their respective windings. It works on the principles of alternating current (AC).

Types of Dry Type Medium Voltage Transformers

 
Here are some types of medium voltage transformers we offer.
 

• Single-phase isolation/distribution transformers: These are designed for low-power supplies, electric heating equipment, and systems that require rounding the load.
• Energy-efficient medium voltage distribution transformers: These specially designed energy-efficient transformers help reduce transmission and distribution losses. They are typically used in local power distribution units.
• Industrial control transformers: These transformers are specially designed for machine tool control circuit applications. They are designed to handle high in-rush currents that occur due to the energizing of electromagnetic components.

Benefits of MV Transformers

Medium voltage (MV) Transformers offer numerous benefits, making them essential components in electrical distribution networks, industrial operations, and renewable energy applications. Below are the key benefits MV transformers provide.

1. Reliable Voltage Regulation: MV transformers efficiently step down voltage levels, ensuring that the appropriate voltage is delivered as per requirement.
2. Protection Against Electrical Faults: MV transformers have built-in protective systems, like circuit breakers, fuses, and relays, to detect and respond to overcurrent, short circuits, or voltage imbalances, ensuring safe operation.
3. Low energy losses: Modern MV transformers have advanced core materials and efficient winding configurations to reduce energy losses (core and copper losses), thus lowering operating costs and improving overall efficiency.
4. Flexibility and customization options: MV transformers are available in various configurations to suit specific environmental and operational conditions, from indoor installations to harsh outdoor environments.
5. Noise reduction technology: MV transformer can operate quietly. This leads to reduction in noise, which is a requirement in some industrial applications..
6. Easy installation and maintenance: MV transformers are available in compact, modular designs that allow for easier transportation, installation, and integration into existing power systems or new projects.
7. Compatibility with smart grid and advanced systems: MV transformers can be compatible with smart grid technology, allowing for automated voltage regulation, real-time monitoring, and better integration with renewable energy sources.

Applications of MV Transformers

Medium voltage (MV) Dry Type Transformers are used in various applications across industries and sectors:

1. Manufacturing plants: MV transformers provide the necessary power for large-scale machinery, motors, and production equipment in manufacturing facilities. In mining sites, MV transformers are used to power heavy-duty mining equipment such as conveyors, crushers, and processing plants. These transformers are also used in petrochemical plants and refineries.
2. Power distribution substations: MV transformers are essential components in utility substations, where they step down high voltage transmission power to medium voltage levels suitable for distribution across cities and towns. They enable safe and efficient distribution of electricity to commercial and residential areas.
3. Power transmission systems: In utility networks, MV transformers work as intermediate transformers that manage voltage levels between long-distance transmission lines and local distribution networks. They minimize transmission losses and ensure stable voltage delivery over large areas.
4. Solar power plants: In solar photovoltaic (PV) plants, MV transformers step up the voltage generated by solar arrays to medium voltage levels, facilitating the transfer of power to the grid or local distribution systems.
5. Commercial buildings and complexes: These transformers find application in power supply units of commercial buildings like shopping malls, office buildings or mixed-use developments. They convert grid voltage to levels suitable for lighting, HVAC systems, elevators, and other building infrastructure.
6. Transportation and infrastructure projects: MV transformers are employed in railway systems to step down voltage from transmission lines to levels suitable for train operations and railway infrastructure; in large transportation hubs like airports and seaports, MV transformers supply power to various systems. Urban transportation systems, such as metro and tram networks, use MV transformers to convert grid power to levels suitable for running electric trains and maintaining infrastructure.
7. Oil and gas industry: MV transformers supply power to pumping stations along oil and gas pipelines, ensuring consistent flow and pressure management over long distances.

How to Choose the Right MV Transformer for Your Project

When choosing a medium voltage transformer, considering these factors may help you make an informed decision. Here’s a step-by-step guide to selecting the right MV transformer for your project:

1. Specify your voltage requirement: First, identify the voltage of your power source (primary voltage) and the required output voltage (secondary voltage) for your equipment or facility. The transformer configuration should match these levels precisely to ensure compatibility and avoid overloading.
2. Define the power capacity: Calculate the total power consumption of your system or equipment. Depending on the criticality of the application, selecting a transformer with a high kVA efficiency rating can provide significant long-term savings.
3. Assess environmental and site conditions: Select a transformer design that fits your site conditions, such as compact dry-type for indoors or robust oil-filled for outdoor use. If the location has extreme weather, choose a transformer designed to withstand specific temperatures and humidity levels.
4. Look for efficiency and loss reduction: Check the transformer’s efficiency to reduce operational costs and minimize power losses. For installations near residential or commercial buildings, consider transformers with low-noise operation.
5. Evaluate cooling requirements: Select a transformer with appropriate cooling methods for your operational needs, like natural air cooling for smaller loads and forced cooling for high-demand setups.

At Bruce Electric, we offer new, reconditioned, and used medium voltage transformers from different brands. Click on RFQ Now beside every transformer.

Frequently Asked Questions (FAQs)

1. Is 13.8 kV medium voltage?

Is 13.8 kV kV is considered a medium voltage for an electrical transformer.

2. What is the difference between MV and HV?

Medium voltage power lines (MV) carry electricity at voltages between 1 kV and 35 kV. High voltage power lines (HV) transmit electricity at voltages from 35 kV to 110 kV.

3. What is the typical temperature rise of medium voltage transformers?

Temperature rise classes include:

• 80°C rise (best efficiency, longest life)
• 115°C rise (standard efficiency)
• 150°C rise (higher thermal stress, lower efficiency)

4. Can dry-type MV transformers be used outdoors?

Yes, but they require weatherproof enclosures (NEMA 3R, 4X, or IP55) for protection against:

• Rain, dust, and pollutants
• High humidity
• Extreme temperatures

5. What are the main failure modes of MV transformers?

• Overheating due to poor ventilation or overload
• Moisture absorption in high-humidity environments
• Partial discharge in epoxy resin insulation (leading to insulation breakdown)
• Mechanical stress from frequent short-circuit currents