Navigating the world of transformers can be complex, especially with the technical jargon and specialized terms often used. To help you better understand these concepts, we’ve compiled a glossary of key transformer terms essential for designing, maintaining, and optimizing these critical devices.
1. kVA (Kilovolt-Ampere)
A unit of apparent power that represents the transformer’s capacity. It indicates the total power the transformer can handle, combining real and reactive power.
2. HV (High Voltage)
The side of the transformer with the higher voltage rating, typically used to receive power from the grid or transmit electricity over long distances.
3. LV (Low Voltage)
The side of the transformer with the lower voltage rating, used to distribute electricity to end users or equipment.
4. Switches
Devices used to connect, disconnect, or reroute the electrical circuit in a transformer system. Common types include:
- Load Break Switches: Allow safe switching under load conditions.
- Disconnect Switches: Used to isolate the transformer for maintenance or safety.
5. Core
The magnetic center of a transformer, typically made of silicon steel or amorphous materials, that concentrates the magnetic flux created by the alternating current.
6. Winding
The coils of conductive material (usually copper or aluminum) that carry current within the transformer. Transformers have:
- Primary Windings: Connected to the input power source.
- Secondary Windings: Connected to the output load.
7. Tap Changer
A device used to adjust the transformer’s output voltage by changing the number of turns in the winding. Types of tap changers include:
- On-Load Tap Changers (OLTC): Operate while the transformer is energized.
- Load Tap Changers (LTC): Maintain voltage under varying load conditions.
- No-Load Tap Changers (NLTC): Require the transformer to be de-energized to adjust taps.
8. Transformer Oil
A specialized insulating and cooling fluid used in oil-filled transformers to dissipate heat and provide insulation. Common fluids include:
- Mineral Oil
- FR3 Fluid: Biodegradable and with a higher flash point, making it ideal for high-risk areas.
9. Impedance
A measure of the opposition a transformer offers to alternating current, expressed as a percentage. Transformer impedance affects voltage regulation and fault current levels.
10. Bushing
An insulated device that allows a conductor to pass safely through the transformer’s tank, maintaining electrical isolation from the grounded tank.
11. Conservator Tank
An auxiliary tank in oil-filled transformers that accommodates oil expansion and contraction due to temperature variations.
12. Load Loss
Also known as Winding Loss, this refers to the energy lost due to the resistance of the windings when the transformer is under load.
13. No-Load Loss
Also known as Core Loss, this occurs even when the transformer is not supplying load. It is caused by the magnetization of the core and includes hysteresis and eddy current losses. Learn more about Understanding Electrical Transformer Losses.
14. Pad-Mount Transformer
A pad-mount transformer is a ground-mounted transformer enclosed in a metal housing for outdoor installation. These are commonly used in residential, commercial, and industrial applications where aesthetics and safety are important.
15. Pole-Mount Transformer
A pole-mounted transformer is installed on utility poles, typically used in rural or urban settings for distributing electricity to smaller loads such as homes and businesses.
16. Cooling Methods
Systems used to dissipate heat from the transformer. Common types include:
- ONAN (Oil Natural Air Natural): Passive cooling using natural convection of oil and air.
- ONAF (Oil Natural Air Forced): Uses fans to force air circulation.
Discover additional cooling combinations or learn more about Understanding the Cooling Classes in Substation Transformers.
17. Fault Current
The abnormal current flow through a transformer due to faults like short circuits. Transformers are designed to withstand specific fault current levels.
18. Nameplate
The specifications provided by the manufacturer, including voltage, power capacity, impedance, and cooling type.
19. Step-Up Transformer
A transformer that increases the voltage from the primary winding to the secondary winding. Commonly used in power generation to transmit electricity over long distances.
20. Step-Down Transformer
A transformer that reduces voltage from the primary winding to the secondary winding, typically used in distribution systems.
Why Master These Terms?
Understanding these terms can enhance your ability to select, operate, and maintain transformers effectively. Whether you’re an engineer, technician, or procurement specialist, mastering this vocabulary is essential for navigating the transformer industry.
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