Portrait view of a high-voltage current transformer in a power substation yard

Описание: Portrait view of a high-voltage current transformer in a power substation yard #shortsviral


In electrical engineering, #CT stands for Current Transformer. It is a specialized type of "instrument transformer" designed to measure and monitor the high electrical currents flowing through power lines safely.
Think of it as a "#step-down" device for #current: it takes a massive amount of electricity (thousands of amps) and converts it into a very small, proportional amount (typically 5A or 1A) that standard meters and protective relays can handle.


How does a current transformer work?

A current transformer (CT) is a type of instrument transformer that measures high electrical currents flowing through power lines safely. Here's a simplified explanation:

Principle: A current transformer works on the principle of electromagnetic induction, similar to a regular transformer. It consists of two coils: a primary coil and a secondary coil, which are magnetically coupled.

Working:

1. The primary coil carries the high current to be measured, which generates a magnetic field.
2. The magnetic field induces a proportional current in the secondary coil.
3. The secondary coil is connected to a measuring device, such as an ammeter or a protection relay.
4. The current in the secondary coil is proportional to the primary current, but at a much lower level, making it safe to measure.

Key characteristics:

The CT's primary coil is designed to carry the high current, while the secondary coil is designed for a standard low current (usually 1A or 5A).
The ratio of primary to secondary current is fixed and defined by the CT's turns ratio.
CTs provide electrical isolation between the primary and secondary circuits, ensuring safety for personnel and equipment.

Applications:

Power system monitoring and protection
Electrical metering and billing
Fault detection and isolation

In summary, a current transformer works by using electromagnetic induction to step down high currents to a safe and measurable level, allowing for accurate monitoring and protection of electrical systems.

What are the types of current transformers?

Current transformers (CTs) are categorized based on their applications, construction, phases, and core types. Here's a breakdown of the different types:

Types of Current Transformers Based on Applications:

Metering Current Transformers: Used for safe measurement of high currents, these CTs are ideal for industrial-scale power systems, power grids, and residential buildings for billing purposes. They're made from premium grade laminated silica steel cores.
Protection Current Transformers: Designed to protect electrical circuits against overloading and short-circuits, these CTs monitor and respond to fault conditions in electrical systems. They're widely used in power plants and industrial setups.

Types of Current Transformers Based on Construction:

Bar-Type Current Transformers: Contain a solid bar placed permanently through the window, these CTs are designed for mounting in-line with busbars and are used in high-current applications.
Cable-Type Current Transformers: Installed on fully insulated medium and high voltage cables, these CTs are flexible and cost-effective, making them perfect for load analysis in commercial, residential, and industrial applications.
Bushing-Type Current Transformers: Designed for monitoring and protection in high-voltage systems, these CTs are widely used in substations for accurate current measurement and protection.
Block-Type Current Transformers: Compact and designed for confined spaces, these CTs are commonly used in low and medium-voltage applications for metering and protection.

Types of Current Transformers Based on Phases:

Single-Phase Current Transformers: Work on a single-phase power supply and are used in power distribution systems for domestic and commercial usage.
Three-Phase Current Transformers: Contain three interconnected single-phase transformers in a single housing.

Types of Current Transformers Based on Core Types:

Wound Core Current Transformers: Not described in detail, but a type of CT based on core construction.
Toroidal (Ring) Core Current Transformers: Also known as "ring type" CTs, these are constructed of an iron toroid and are wound with secondary turns.
Split Core Current Transformers: Another type of CT based on core construction.¹ ²