Dry type transformers are electrical devices designed to transfer energy from a high-voltage primary source to a lower-voltage secondary circuit through electromagnetic induction. Unlike oil-filled transformers, which rely on oil for cooling and insulation, dry type transformers use solid insulation materials and air-based cooling systems. This makes them safer, cleaner, and well-suited for indoor environments.
Dry type transformers use materials such as epoxy resin or polyester varnish to insulate the windings and the core. This also helps seal the unit against moisture, extending service life.
These transformers are cooled either by natural air circulation (convection) or forced air using fans. Effective cooling ensures safe operation and prevents overheating during continuous use.
A major advantage is their enhanced fire safety. Since no flammable oil is used, the risk of fire is significantly reduced, making them ideal for buildings with strict safety standards.
Dry type transformers are commonly used indoors, as they don’t require oil containment systems. This makes installation simpler in urban or sensitive environments.
With no oil to monitor or replace, maintenance requirements are minimal. This reduces downtime and lowers operational costs.
The absence of oil also means there is no risk of soil or water contamination, making these transformers more eco-friendly.
A dry type transformer contains many interdependent components that enable energy transfer. Knowing these parts and their roles can help you understand how a transformer works. Here is a list of dry type transformer parts:
The primary winding, connected to the power source, conducts alternating current along a circular path around the core to generate a magnetic field. This field induces a voltage across the secondary winding, enabling energy transfer between the primary and secondary voltages. The precise number of turns within each winding determines the transformer’s voltage transformation ratio. Additional layers to the windings can enhance performance.
· Core: Laminated sheets of premium silicon steel minimize eddy current losses and magnetic hysteresis, enhancing energy efficiency.
· Primary winding: Connected to the power source, it generates a magnetic field that initiates energy transfer.
· Secondary winding: Induces voltage through electromagnetic induction via the core, transmitting energy to the load.
Solid insulation materials ensure electrical separation between the core, windings and winding layers. These materials separate the windings into multiple layers, mitigating potential short circuits and guaranteeing safe energy transmission. By covering windings and isolating them from the magnetic core, the insulation fortifies the transformer against voltage breakdowns, improves resistance to environmental stressors and enhances thermal performance.
Typical insulation materials include:
· Polyester varnish
· SG-200 glastic sheets and winding combs
· Dupont Nomex insulation
· Advanced composites such as GPO-3 fiberglass
The cooling mechanisms, typically a blend of natural convection and forced air cooling techniques, maintain the transformer’s optimal operational temperature. Balancing these cooling mechanisms helps the transformer’s longevity and reliability.
· Natural convection: Natural convection employs thermal buoyancy, where hot air rises and cool air falls. Vents and ducts facilitate the upward movement of hot air, drawing in cooler air for passive cooling. This heat transfer process and the strategic design of cooling ducts ensure effective dissipation.
· Forced air cooling: Fan cooling amplifies airflow, actively dissipating heat and maintaining optimal temperatures.
The enclosure protects the core and windings from the elements and keeps personnel out for safety.
Terminals and supplementary components such as bus bars and bushings integrate the external circuits with the transformer’s internal windings and prevent flashovers. These components bolster electrical efficiency, promote isolation and fortify the transformer’s role within a larger electrical network.
· Terminals: Ensure reliable energy transfer.
· Bus bars: Robust conductors designed for high-current applications that enhance electrical efficiency.
· Bushings: Insulating components that extend through the enclosure to facilitate secure external connections.
A de-energized tap changer allows for voltage adjustment. Its essential function is to alter the winding turns ratio for voltage adjustment.
The grounding system redirects electrical faults away from the transformer, channeling them safely into the ground. This safety measure reduces the probability of electrical shocks, equipment damage, potential fires, injury and death. The grounding system contains a grounding electrode, surge arrestors and fault indicators.
· Grounding bus: Provides a low-resistance path for fault currents to safely dissipate into the ground.
· Surge arrestors: Divert transient overvoltage, safeguarding the transformer against voltage spikes.
· Fault indicators: Detect abnormal fault conditions to assist in maintenance and protection.
Temperature monitoring and protection mechanisms prevent overheating, a significant concern in transformer function, and take action if temperatures rise too high, preserving the transformer’s operational integrity. Integration with supervisory control and data acquisition (SCADA) systems facilitates real-time data relay, enabling remote monitoring and analysis of temperature trends.
· Temperature sensors: Thermocouples monitor the temperature in each coil near the top where the hottest spot is. At certain set points they can activate the cooling fans, and once the unit cools to a certain set point, the fans can be switched off.
· Protection relays: Relays can activate alarms, shutdowns or remote communications in response to excessive temperatures.
Discover the advanced capabilities of Tianya medium-voltage dry type transformers, engineered to meet your specific requirements. Our experienced team is ready to provide detailed technical support and guidance on the advantages these transformers can bring to your operation.
Beyond transformer construction, we also deliver a full range of services including custom bus work, retrofitting solutions and emergency replacements, ensuring that your system remains reliable under all conditions.
To explore how our transformers can support your projects, simply complete our online quote request form and receive detailed pricing and technical information tailored to your needs.
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