Accurately Perceive Power Pulses: An Overview of Transformer Classifications

In modern power systems, transformers (instrument transformers) serve as the bridge connecting primary and secondary systems, acting as key equipment to ensure the safe, stable, and efficient operation of power grids. As critical devices that convert high voltage or large current into standardized low voltage (100V) or small current (5A/1A), they not only achieve electrical isolation to protect equipment and personal safety but also provide accurate and reliable signal inputs for measuring instruments and relay protection devices. People's Electrical Appliances Group has always been driven by technological innovation, delivering high-quality, high-reliability transformer products to support the intelligent and safe development of power systems.

Classified by Measurement Object

1. Current Transformer (CT): Linearly converts large primary current (from several amperes to tens of thousands of amperes) into standard 5A, 1A, or smaller current, supplying measurement, metering, and protection devices.

2. Voltage Transformer (VT): Linearly converts high primary voltage (up to 500kV and above) into standard 100V, 100/√3V, or lower voltage, enabling safe sampling for measurement, protection, and monitoring devices.

Classified by Insulation Medium

1. Dry-Type Transformer: Cast with epoxy resin or silicone, oil-free and gas-free with extremely low explosion risk. Suitable for high fire-safety demand scenarios such as subways, commercial complexes, and high-rise buildings.

2. Oil-Immersed Transformer: Insulated and cooled by mineral oil, featuring high insulation strength and obvious cost advantages. Commonly used in outdoor substations and transmission corridors.

3. Gas-Insulated (SF₆) Transformer: Compact, pollution-resistant, and earthquake-resistant. Ideal for high-altitude, alpine, high-humidity environments and integrated GIS (Gas-Insulated Switchgear) solutions.

4. Electronic (Optical/Capacitive) Transformer: Adopts Rogowski coil, optical fiber sensing, or capacitive voltage division principles. With a simple insulation structure, wide dynamic range, and digital output naturally compatible with IEC 61850, it has become the "new infrastructure standard" for smart substations and digital power grids.

Classified by Accuracy Class

1. Measurement Class: 0.1, 0.2, 0.5 classes. Focus on trade settlement and precision measurement, used in gateway energy meters and laboratory standards.

2. Protection Class: 5P, 10P, TPY, TPS, etc. Emphasize saturation characteristics and DC component resistance, applied in relay protection devices.

3. Composite Class: Meets dual requirements such as 0.2/5P and 0.5/10P, realizing "one core for two purposes" to reduce cabinet space and overall cost.

Classified by Installation Scenario

1. Indoor Type: Epoxy resin casting, compact and maintenance-free. Suitable for power distribution rooms, pad-mounted transformers, and data centers.

2. Outdoor Type: Porcelain or silicone rubber composite housing, UV-resistant and pollution-flashover resistant. Used in transmission towers and wind farm step-up substations.

3. GIS-Built-in Type: Co-mounted with gas-insulated switches, modular and space-saving. Compatible with urban underground substations and offshore platforms.

4. Split-Core/Through-Core Type: Installable without power interruption. Suitable for existing system upgrades and rapid expansion of power distribution IoT.