Cooling fans for dry-type transformers: the core component for increased capacity and safety

What is a dry-type transformerCooling Fans?

A dry-type transformer cooling fan is a device specifically designed for forced air cooling (AF, Air Forced) of dry-type transformers. Typically mounted on the bottom, side or top of the transformer, it actively blows the windings and core surfaces of the transformer by generating a powerful airflow to significantly improve its cooling efficiency. More than just a few simple fans, this system is an intelligent cooling solution tightly integrated with the transformer's temperature control system, and is a key part of unlocking the potential of dry-type transformers and ensuring their safe operation.

Why do dry-type transformers need cooling fans?

Dry-type transformers rely on air as the insulation and cooling medium. In the state of natural cooling (AN, Air Natural), their heat dissipation capacity is limited and therefore their rated capacity is conservative. The addition of cooling fans is useful in the following core areas:

1. Upgrading of operational capacity

This is the most important role of the fan. Through forced air cooling, it can effectively take away a large amount of heat generated during the operation of the transformer, so that its winding temperature is maintained within the safety limit. According to the industry standard and design, after installing the air-cooling system, the output capacity of dry-type transformer can be increased by 40% to 50% on the basis of natural cooling, which means that a 1000kVA transformer can be safely used as a 1400kVA or even 1500kVA transformer after the fan is activated, so as to meet the demand for peak hour or temporary capacity increase of electricity consumption. .

2. Securing overloads

When the transformer is overloaded for a short period of time due to an unexpected situation or seasonal load, its internal temperature will rise sharply. The cooling fan can respond quickly to inhibit the speed of temperature rise through strong heat dissipation, buying valuable time for system adjustment and avoiding insulation damage due to overheating, which greatly enhances the transformer's overload capacity and operational reliability.

3. Extension of useful life

Temperature is the decisive factor influencing the aging of transformer insulation materials. The air-cooling system effectively reduces the average operating temperature of the transformer under high loads and slows down the aging process of the insulation material, thus significantly extending the overall service life of the transformer.

4. Improving environmental adaptation

In places with high ambient temperatures (e.g. distribution rooms in summer, poorly ventilated basements) or at high altitudes, the thin air causes the natural heat dissipation effect to deteriorate. At this time, forced air cooling becomes a necessary guarantee to ensure that the transformer can be sufficient output and safe operation.

How does a cooling fan system work?

Dry-type transformer air-cooling system is a closed-loop automatic control system, its workflow is as follows:

First, temperature sensors (usually Pt100 platinum RTDs) installed inside the transformer's three-phase windings monitor the temperature of the windings in real time. The temperature data is then transmitted to a dedicated dry transformer temperature controller. The O&M staff can preset several temperature control points on the controller, such as “fan start temperature” (e.g. 100°C) and “fan stop temperature” (e.g. 80°C).

When the temperature controller monitors that the temperature of any phase of the winding reaches or exceeds the “fan start temperature”, it will automatically close the relay, connect the power supply of the fan, and all the fans start to run. The powerful airflow generated by the fan will be along the specially designed air ducts of the transformer, blowing evenly over the windings and iron core cooling surface, the heat will be efficiently taken away. As the forced cooling proceeds, the temperature of the windings gradually decreases. When the temperature is lower than the preset “fan stop temperature”, the thermostat will automatically disconnect the fan power supply, the fan stops running to save energy. In addition, the thermostat is equipped with higher setpoints for “over-temperature alarm” (e.g. 130°C) and “over-temperature trip” (e.g. 155°C) to provide ultimate over-temperature protection for the transformer.

Types and selection of fans

Cooling fans used for dry-type transformers are mainly categorized into the following two types according to their airflow direction and structure:

Cross-Flow Fan

With a long cylindrical impeller, the air enters from one side, and blows out from the other side in a “face”, which can form a uniform air curtain. Its structure is compact, the air volume is uniform, can cover the entire width of the winding, heat dissipation without dead angle, is currently the most mainstream choice for medium and large dry-type transformers.

Axial Fan

Similar to an ordinary electric fan, air is drawn in and out in an axial direction, forming a “columnar” airflow. The single unit has a high air volume and high air pressure. Usually used as a side-by-side combination of multiple fans, mounted on the side or bottom of the transformer.

When selecting the fan, it is necessary to consider the capacity of the transformer, structure, temperature rise limit and noise requirements and other factors to ensure that the total air volume of the fan, air pressure and other parameters can meet the heat dissipation needs of the transformer.

Frequently Asked Questions (FAQ)

Q: Is the blower on all the time, or does it start and stop automatically?

A: It is automatic start TPing. The operation of the fan is completely controlled intelligently by the dry transformer temperature controller based on the real-time temperature of the transformer windings. It starts only when the transformer is under high load and at high temperature, thus realizing high energy efficiency.

Q: What happens if one of the fans breaks?

A: Professional air cooling systems are designed with redundancy in mind. Even if a single fan fails, the remaining fans can still provide most of the cooling capacity. At the same time, high-end temperature control systems may also have a fan failure detection function. Once a fan is found to be not spinning, an alarm signal will be sent out, prompting operations and maintenance personnel to replace it in a timely manner.

Q: Will the distribution room become noisy with the addition of the fan?

A: There will be a certain degree of increase, but modern cooling fans for transformers are designed to optimize the noise. By using high quality bearings, optimized blade design, and reasonable installation methods, the noise can be controlled within acceptable limits. For places with strict requirements on noise, low-noise models of fans can be selected.

Q: Do cooling fans need regular maintenance?

A: Required. Maintenance is relatively simple, mainly checking whether the fan can start normally on a regular basis, removing dust accumulation on the fan blades and protective grille to prevent the air duct from being blocked and affecting the heat dissipation effect. A clean operating environment is the basis for ensuring that the fan works efficiently for a long time.

Choose our cooling fans for your transformer!

A high-performance, reliable cooling fan system is the best investment in your expensive transformer assets. Not only does it bring you tangible capacity improvements and economic benefits, but it is also a key part of grid safety and accident prevention.

Our company specializes in providing high quality dry-type transformer cooling fans and supporting temperature control solutions. Our products use top-quality motors and optimized air duct design, featuring high air volume, low noise, long life and maintenance-free. Whether you are a transformer manufacturer, a complete set of equipment factory or an end user, we can provide the most cost-effective customized products and professional technical support according to your specific needs.Contact us today and let our experts “customize” a perfect cooling solution for your transformer!