Distribution Transformer: How It Works & How to Maintain It

Key Takeaways

• A distribution transformer is electrical equipment working to reduce the voltage, allowing it to be distributed safely to the final consumers.
• The types of distribution transformers are based on the voltage, cooling method, and phase.
• A distribution transformer must receive routine maintenance, such as physical maintenance, load monitoring, tightening of connections, and thermography scans. 

The optimal electricity supply is not only about the electrical capacity but also about how the distribution system transfers the electricity according to the needs. To make the transfer efficient, the electricity is distributed at high voltage. 

Yet, high voltage may not be sufficient for consumer equipment, including in the industrial sector. This system requires a distribution transformer. Learn the function, mechanism, and types below. 

What Is a Distribution Transformer?

A distribution transformer is electrical equipment to decrease the voltage, usually 33 kV or 11 kV, from the transmission grid to lower voltages, such as 240 V or 415 V. 

This device keeps the current safe and stable for the final consumers, like residential areas, offices, and industries. The operation runs continuously, whether in use or not. 

The main components of a distribution transformer are the primary coil connected to the high-voltage electricity and a secondary coil transferring low-voltage electricity. Both coils are wrapped around the laminated magnetic core, helping reduce energy loss and increase transformer efficiency. 

Despite ensuring current safety, a distribution transformer can undergo several issues, such as overheating from overload, voltage fluctuation due to unbalanced load, and isolation failure due to humidity. 

How a Distribution Transformer Works

The distribution transformer works based on electromagnetic induction. When alternating current flows through the primary coil, it generates magnetic flux (magnetic field flow) in the transformer core. The flux induces voltage in the secondary coil. The amount of voltage depends on the turns ratio between the primary and secondary coils. 

Since the secondary coil has fewer turns than the primary one, the voltage becomes lower. This way, a distribution transformer can reduce the voltage according to the final consumer’s needs. 

Related article: 7 Characteristics of Voltage Fluctuation & Its Causes

Types of Distribution Transformers

A distribution transformer is categorized by voltage level and cooling methods. Here is the complete information:

1. Based on the Voltage Level

Based on the voltage level, a distribution transformer is divided into primary and secondary transformers as follows:

• Primary transformers: Transformers with a standard voltage of 20 kV used to supply electricity to factories, utility systems, urban power grids, and industrial areas.
• Secondary transformers: Transformers with a standard voltage of 220/380 V. They are typically used in residential and commercial areas.

2. Based on Cooling Methods

According to the cooling methods, distribution transformers are categorized into dry-type transformers and oil-immersed transformers:

• Dry-type transformer: It uses air as the cooling medium. Widely used in hospitals and shopping centers, it is known for being safer, easy to maintain, and moisture-resistant.
• Oil-immersed transformer: The oil helps dissipate heat, enabling the transformer to operate efficiently. Due to its high capacity, it is widely used in areas with heavy loads, such as the industrial sector.

How to Maintain a Distribution Transformer

To maintain device performance, extend service life, and prevent unexpected damage, distribution transformers must undergo maintenance that includes:

• Visual inspection: Checking the physical condition of the transformer (including bushings, the grounding system, and electrical connections), listening for abnormal noises, and checking for discoloration at the connections.
• Dust and dirt removal: The surfaces of external components, particularly the radiator and cooling fans, should be cleaned periodically with a dry cloth to ensure unobstructed airflow and prevent overheating.
• Load monitoring: Monitor the load to prevent overloading, extend the transformer’s service life, and maintain its efficiency.
• Oil testing and analysis: Check the dielectric strength, acidity level, and the oil’s color and appearance. Oil testing should be performed at least once a year but may be done more frequently if the transformer operates under heavy load conditions.
• Thermographic scanning: Use an infrared camera to help identify hot spots and cooling system issues that are not immediately visible.

You may be interested in:  How to Save Industrial Electricity in a Sustainable Way

Differences Between Distribution Transformers and Power Transformers

Despite having a similar job of changing voltage using electromagnetic induction, distribution transformers and power transformers have several technical differences, such as: 

Build a Stable Electricity System with CDI Group

The distribution transformer's stability significantly impacts overall business productivity. Therefore, ensure that their selection, installation, and maintenance are handled exclusively by qualified professionals.

PT Chandra Daya Investasi Tbk (CDI Group), through its subsidiary PT Krakatau Chandra Energi (KCE), serves as a reliable power solution to help create a stable electrical system for your business. We provide electricity and power system services.

In our electricity supply services, KCE operates a Combined Cycle Power Plant (CCPP)-based gas-fired steam power plant with a capacity of 120 MW. This system consists of 2 Gas Turbine Generators (GTGs), 2 Heat Recovery Steam Generators (HRSGs), and 1 Steam Turbine Generator (STG).

Meanwhile, power system services are divided into three main segments, namely:

• Operation and Maintenance (O&M) of power plants.
• Engineering, Procurement, and Construction (EPC) for power systems.
• Repair and overhaul services for transformers and electric motors.

Currently, KCE has earned the trust of over 200 customers from the industrial, business, social, and government sectors, as well as over 1,500 residential customers.

This is the right time for CDI Group and KCE to be #YourGrowthPartner by providing reliable and efficient electricity solutions. Contact us now and schedule a consultation!

More to explore:  Smart Grid: Definition, Benefits, and How It Works

Frequently Asked Questions (FAQ)

Here are some frequently asked questions about industrial transformers and their answers:

1. Are Substations and Transformers the Same Thing?

No. A substation is a building or centralized area within an electrical power system that serves to regulate, protect, and distribute electrical current. A transformer is a device used to change the voltage level from one circuit to another through electromagnetic induction.

2. What Causes a Distribution Transformer to Overload?

A distribution transformer can overload due to changes in energy consumption patterns, inflexible distribution planning, or an increase in electrical load that isn’t matched by an increase in capacity.

3. How Do You Check If a Transformer Is Damaged?

You can check a transformer using a digital multimeter. The steps include measuring the input and output voltages, the coil resistance, and testing the output consistency.

4. What Is the Capacity of a Distribution Transformer?

The capacity of commonly used distribution transformers ranges from 50 kVA to 2,500 kVA.