20KV Dry Type Electriacl Distribution Transformer

20KV Dry Type Electrical Distribution Transformer

Cotenele is a large manufacturer and exporter for 20KV Dry Type Electrical Distribution Transformer from China. Our 20KV dry-type transformers have features of longer power supply radius, lower voltage drop, reduced line losses, and less consumption of non-ferrous metals. These 20kV dry-type transformers are increasingly used in high-rise buildings, commercial centres, petrochemical plants, mines, power plants, airports, and many other locations.

The 20KV Dry Type Electrical Distribution Transformer which manufactured by Cotenele company is an important equipment in the 20kV power distribution system. Its voltage level lies between 10kV and 35kV. It compensates for the shortcomings of 10kV power distribution lines and is a key recommended power distribution product by State Grid Corporation of China and various provinces. The 20kV dry-type transformer mainly uses solid insulating materials and an air cooling system. It has excellent safety performance, good environmental compatibility, low maintenance requirements, and is increasingly popular in modern power distribution systems. Unlike oil-immersed transformers, dry-type transformers do not have problems such as oil leakage, fire risks, and environmental pollution. Our 20KV Dry-type transformers comply with relevant international standards IEC 60076-11 and IEEE C57.12.01.

Main technical parameters

Operating Conditions

Normal Service Conditions:

1. Altitude: ≤1000m (standard type)

2. Ambient temperature:

3. Maximum: +40°C

4. Minimum: -25°C (outdoor dry-type); -5°C (indoor dry-type)

5. Maximum monthly average: 30°C

6. Maximum annual average: 20°C

7. Relative humidity: Should be below 93%; no condensation on coil surfaces

8. Power supply: Three-phase voltage should be approximately symmetrical; the voltage waveform should be approximately sinusoidal

Special Conditions:

For altitudes above 1000m, an altitude-modified (plateau) dry-type transformer can be supplied.

What is a 20kV Dry-Type Transformer?

A 20kV dry-type transformer is a transformer with a primary rated voltage of 20kV, whose core and windings are not immersed in insulating oil. Instead, it relies on air convection for cooling—hence the name "dry-type." In simple terms, the core and coils are not oil-filled; they are solid-insulated, typically with epoxy resin.

Its working principle is based on electromagnetic induction. When the primary (high-voltage) winding is energised with an alternating current, an alternating magnetic flux is produced in the iron core. This flux links with the secondary (low-voltage) winding and induces an electromotive force (EMF) in it. By choosing the appropriate ratio of primary to secondary winding turns, the input voltage of 20 kV can be reduced (or increased) to the desired output voltage, such as 0.4 kV, 10 kV or other voltage levels.

The internal structure mainly consists of the following parts:

1. Core: made of cold-rolled, grain-oriented electrical steel laminations with 45° full-miter joints to reduce losses. The core is clamped using hole-less banding and rigid pull-plate mechanisms, and its surface is often coated with a special resin for moisture and rust protection.

2. Windings: the low-voltage (LV) winding is wound with full-width copper foil on a dedicated foil-winding machine, using two axial cooling ducts per column. The high-voltage (HV) winding uses a sectionalised layer-type structure with one axial cooling duct. Both windings feature honeycomb-type cooling ducts with standardised metal duct plates for good heat dissipation.

3. Insulation system: an insulating cylinder is placed between the HV and LV windings to provide electrical clearance. The entire coil assembly is vacuum-cast with epoxy resin, forming a dense, void-free solid structure that offers high mechanical strength, excellent electrical insulation, and superior moisture resistance.

4. Temperature control system: embedded temperature sensors (usually placed in the upper part of the LV coils) continuously monitor the winding temperatures. The system provides an automatic sequential (cyclic) display of each phase's temperature, with alarm and trip contacts for over-temperature protection.

Product Features

The 20kV dry-type transformer exhibits the following notable features:

1. "Three Lows & Three Highs": low losses, low noise, low partial discharge; high mechanical strength, high electrical strength, and high thermal endurance.

2. Safe & environmentally friendly: fire-retardant, explosion-proof, non-polluting; can be installed directly at load centres.

3. Strong short-circuit withstand capability: the epoxy cast body has a dense structure that withstands short-circuit electrodynamic forces without damage.

4. Low partial discharge level: can be controlled below 10pC (some premium products reach <5pC).

5. Excellent moisture resistance: can operate normally at 100% humidity; no pre-drying is required after a shutdown before re-energising.

6. High overload capacity: can continuously run at 120% load without forced air cooling; with forced air cooling (AF), it can sustain 150% rated load.

7. Maintenance-free: low losses and economical operation; essentially maintenance-free.

8. Compact & lightweight: small footprint and low installation costs.

Product Classification For 20kV Dry-Type Transformer

Product Advantages

1. Enhanced supply performance: extended transmission distance, minimized voltage decline, and lower line losses result in superior power quality.

2. Substantial energy efficiency: featuring exceptionally low no-load and load losses, fully meeting the stringent requirements of the latest GB20052-2024 energy-efficiency standard.

3. Flexible installation: can be decentralised at load centres without the need for oil containment pits or firewalls, reducing capital investment.

4. Low operating costs: maintenance-free design leads to low overall operating expenses.

5. High reliability: high mechanical strength, good seismic performance, and excellent lightning impulse withstand capability.

6. Strong adaptability: insensitive to humidity and dust, suitable for harsh environments with high fire protection requirements, fluctuating loads, or polluted/damp conditions.

Application Scenarios

20kV dry-type transformers are widely used in:

1. Urban infrastructure: urban grid upgrades, high-rise buildings, business centres, commercial complexes

2. Public facilities: theatres, hospitals, hotels, schools

3. Transportation: tunnels, subways, railway stations, ports, airports

4. Power generation & distribution: power stations, underground substations, packaged substations, power plants

5. Industrial sectors: petrochemical, mining, factory workshops, CNC machinery

6. Renewable energy & data centres: wind, photovoltaic projects, cloud computing centres

7. Special locations: laboratories, urban substations in densely populated areas, and any site requiring fire/explosion/moisture protection

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