First and foremost, Measurement Current Transformers (or the measurement winding of a current transformer) deliver grid current data to metering and related devices. This applies within their rated operating current range.

Notably, measurement accuracy is their core performance indicator. It directly determines the reliability of power grid energy metering and load monitoring.

Additionally, their application scenarios cover residential electricity metering, industrial load testing, and grid parameter collection. They cater to diverse data needs in power systems.

By contrast, Protection Current Transformers (or the protection winding of a current transformer) play a critical role in fault response. When grid faults occur, they promptly transmit fault current information to relay protection systems.

Specifically, they require rapid response speed and stable short-circuit performance. This ensures protection devices trigger accurate tripping actions.

Furthermore, they often work with circuit breakers. Together, they minimize fault damage and maintain grid stability.

Secondly, Dry-type Current Transformers use varnish-dipped ordinary insulating materials for insulation.

They offer compact structure, easy maintenance, and flame retardancy. These features make them suitable for indoor switchgear cabinets.

However, ambient humidity affects their insulation performance. Operators must strictly control operating environment conditions.

Similarly, Cast Resin Current Transformers are molded from epoxy resin or other composite materials.

They boast excellent insulation strength, corrosion resistance, and mechanical durability.

This makes them widely used in both indoor and outdoor medium-voltage systems.

Moreover, the integral molding process enhances moisture and dust resistance. It reduces long-term operational failures.

In contrast, Oil-immersed Current Transformers rely on insulating paper and oil. They are typically designed for outdoor use.

They perform exceptionally well under high-voltage and large-capacity conditions. Thus, they are widely used across China’s voltage classes.

Nevertheless, regular oil sampling and testing are necessary. This prevents insulation degradation from oil aging or moisture ingress.

Furthermore, Gas-insulated Current Transformers use insulating gas (e.g., SF6) for main insulation.

They feature compact size, non-flammability, and low maintenance costs.

These advantages make them ideal for high-voltage grids with limited installation space.

However, strict sealing measures are required. Gas leakage would compromise insulation effectiveness.

Thirdly, Electromagnetic Current Transformers convert current via electromagnetic induction.

They have mature technology, stable performance, and low cost. These traits make them the most common type in power systems today.

Additionally, they adapt to a wide range of load conditions. They meet both metering and protection needs.

Meanwhile, Photoelectric Current Transformers use photoelectric conversion technology. This technology is still under further development.

Compared with electromagnetic types, they offer a wide measurement range. They also have no magnetic saturation and strong anti-interference ability.

However, high manufacturing costs and technical complexity limit their large-scale commercial use. Ongoing research focuses on cost reduction and reliability improvement.

Fourthly, Through-wall Current Transformers are designed for wall or switchgear panel installation.

Their structure allows convenient threading of primary conductors. This ensures a compact layout in limited space.

Moreover, they provide effective insulation isolation between indoor and outdoor circuits. This enhances operational safety.

Alternatively, Pillar-type Current Transformers mount on flat surfaces or supporting pillars. They also act as conductor supports for the primary circuit.

This dual-purpose design simplifies installation. It also reduces the number of auxiliary components.

Thus, they are suitable for outdoor power distribution stations. Their robust structure withstands harsh weather like strong winds and heavy rains.

In addition, Bushing-type Current Transformers lack independent primary conductors or insulation structures. They attach directly to electrical equipment’s insulating bushings.

Their space-saving design integrates seamlessly with host devices. This makes them widely used in transformers and circuit breakers.

Furthermore, they eliminate the need for extra installation space. This optimizes the overall structure of power equipment.

Lastly, Active Electronic Current Transformers use air-core coils as primary sensors. Their high-voltage side electronic components need an external power supply.

They deliver high measurement accuracy and fast response speed. This makes them suitable for smart grid real-time data needs.

However, external power reliance increases failure risks during outages. Backup power solutions are therefore necessary.

On the other hand, Passive Magneto-optical Glass Electronic Current Transformers use magneto-optical glass as primary sensors. They operate without external power.

This passive design enhances reliability and reduces maintenance costs. It addresses the power dependency of active types.

Moreover, they offer excellent anti-electromagnetic interference performance. This ensures stable operation in complex electromagnetic environments.

Nevertheless, magneto-optical glass manufacturing is relatively complex. This leads to higher initial costs than active types.