Founded in 1998, Tianrui Electronics is a power signal acquisition and transmission solution provider integrating scientific research, production, sales and service. The main products include: current transformer, current sensor,Rogowski coil,Electrical Instruments,Energy Harvester,Power meter etc.

The company's current three major business areas are: relay protection and automation, smart grid, and new energy. Among them, the main target markets in the field of relay protection are: power sensors and GPS synchronization clock sources; the main target markets in the field of smart grid are: digital power meters and high-voltage electric energy metering devices; the main target markets in the field of new energy are: solar and wind power conversion devices, New energy battery monitoring devices, etc.

A split core current transformer (CT) is a type of current sensor designed to measure alternating current without disconnecting the circuit. Unlike solid core CTs, it has a hinged or separable core that can be easily opened and clamped around an existing conductor, making installation quick and non-intrusive. It works by transforming the high current flowing through the conductor into a smaller, proportional current for monitoring and metering. Split core current transformer(CTs) are widely used in energy management, power monitoring, and protection systems. They are ideal for retrofitting existing electrical systems, offering convenience, accuracy, and safety in applications such as smart grids, building energy management, and industrial automation.

A current sensor is an electronic device that detects and measures the flow of electric current in a conductor, either alternating current (AC) or direct current (DC). It converts the current into a proportional signal, such as voltage or digital output, which can be used for monitoring, control, or protection. Current Transducer(Current sensors) are commonly based on technologies like Current transformers, Hall effect sensors, or Rogowski coils. They are widely applied in power systems, industrial equipment, renewable energy, smart grids, and electronic devices, helping improve energy efficiency, ensure safety, and provide accurate data for automation and management.

A Hall effect current sensor is a device that measures electric current using the Hall effect principle. When current flows through a conductor, it generates a magnetic field. The sensor’s Hall element detects this magnetic field and produces a voltage proportional to the current. This output signal can be processed to monitor AC or DC currents accurately. Hall effect current sensors provide isolation between the measured conductor and the sensing circuit, ensuring safety. They are widely used in power electronics, electric vehicles, renewable energy systems, industrial automation, and battery management due to their high accuracy, reliability, and versatility.

The working principle of a current transformer (CT) is based on electromagnetic induction. When alternating current flows through the primary conductor, it generates a magnetic field around it. This magnetic flux passes through the CT’s magnetic core and induces a proportional current in the secondary winding. The secondary current is a scaled-down version of the primary current, allowing safe measurement and monitoring of high currents without directly connecting measuring instruments to the power line. CTs are essential in metering, monitoring, and protection within electrical power systems.

A current sensing circuit is designed to measure the flow of current and convert it into a readable signal for monitoring or control. It can be built in several ways depending on the application. The simplest method uses a shunt resistor, where the voltage drop across the resistor is proportional to the current. For higher isolation and safety, current transformers or Hall effect sensors are used to detect the magnetic field created by the current. The output signal is then amplified or converted into digital form for microcontrollers, meters, or protection systems.

A Current Transformer (CT) and a Core Balance Current Transformer (CBCT) are both used for current measurement and protection, but they serve different purposes. A CT measures the current in a single conductor by stepping it down to a safer, measurable level, often used for metering and protection. A CBCT, also called a zero-sequence CT, surrounds all three phase conductors (and sometimes neutral) together. It detects imbalance or leakage currents, mainly for earth fault protection. In short, CT focuses on measuring line current, while CBCT focuses on detecting ground faults.

Current sensors are devices that detect and measure the flow of electric current in a conductor, converting it into a signal for monitoring or control. They come in several types based on technology and application. Shunt resistors measure voltage drop to calculate current, suitable for DC and low-frequency AC. Current transformers (CTs) step down high AC currents for metering and protection. Hall effect sensors use magnetic fields to measure both AC and DC. Rogowski coils provide flexible, non-intrusive measurement for high-frequency AC. Each type differs in accuracy, range, isolation, and cost.

 A Rogowski coil is a specialized device designed to measure alternating currents (AC), especially where accuracy, safety, and wide dynamic range are required. Unlike traditional current transformers, it is built without a ferromagnetic core, making it lightweight, flexible, and free from magnetic saturation. These unique characteristics make Rogowski coils highly valuable across industries where monitoring and analyzing electrical current is essential.

General Purpose of Rogowski Coils

The primary use of a Rogowski coil is to measure current flowing in a conductor and convert it into a voltage signal proportional to the rate of change of current. When coupled with an integrator circuit, the signal provides a highly accurate representation of the actual current waveform. Because of their broad frequency response and linearity, Rogowski coils are widely used in power systems, industrial operations, renewable energy, and research applications.

Applications in Power Systems

1. Power Transmission and Distribution
In high-voltage substations and distribution networks, Rogowski coils are employed to monitor load currents and detect faults. Their non-saturating property enables them to measure very high currents, such as those caused by short circuits or switching surges, without distortion.

2. Fault and Transient Detection
Electrical faults and transient events like lightning strikes or switching operations generate fast-changing currents. With their wide bandwidth, Rogowski coils can capture these rapid variations, helping utilities analyze disturbances and improve grid reliability.

3. Harmonics and Power Quality Analysis
Modern electrical systems face increasing harmonic distortion from nonlinear loads such as inverters, computers, and drives. Rogowski coils accurately measure harmonic content, enabling engineers to diagnose power quality issues and comply with grid standards.

Industrial and Commercial Applications

1. Motor and Drive Monitoring
In industrial environments, Rogowski coils are used to measure current in motors, pumps, and variable frequency drives. They help detect overloads, imbalances, or abnormal operating conditions, ensuring equipment reliability and safety.

2. Welding and Furnace Equipment
Processes such as arc welding and induction heating generate high, rapidly changing currents. Rogowski coils are ideal for monitoring these because of their ability to handle both large magnitudes and high-frequency components without distortion.

3. Building and Facility Energy Management
For large commercial buildings and factories, Rogowski coils are integrated into energy monitoring systems. They provide data on current usage, helping facilities optimize power consumption, improve efficiency, and reduce costs.

Renewable Energy Applications

1. Solar Power Systems
In photovoltaic (PV) plants, Rogowski coils measure inverter output currents and grid injection currents. Their accuracy ensures compliance with grid regulations and supports maximum power point tracking (MPPT) strategies.

2. Wind Turbines
Wind turbines require continuous monitoring of currents in generators and converters. Rogowski coils provide this data, enabling safe operation and efficient energy conversion even under fluctuating wind conditions.

3. Battery Storage and Electric Vehicles
Battery systems in renewable integration and electric vehicles rely on precise current measurements for charging and discharging. Rogowski coils help manage these processes efficiently while ensuring battery health and longevity.

Research and Laboratory Applications

Rogowski coils are widely used in academic and industrial research because of their flexibility and accuracy. In laboratories, they measure pulsed currents, switching phenomena in power electronics, and experimental electrical systems. Their ability to capture high-frequency components makes them indispensable for testing converters, inverters, and smart grid technologies.

Advantages of Rogowski Coils

No Magnetic Saturation: They can measure extremely high currents without distortion, unlike traditional transformers.

Wide Frequency Range: Suitable for both low-frequency power currents and high-frequency transients.

High Linearity: Provides accurate readings across small and large current ranges.

Flexible Installation: The coil can be opened and wrapped around existing conductors without interrupting the circuit, making retrofitting simple.

Lightweight and Portable: Easier to handle in field applications compared to bulky current transformers.

Enhanced Safety: Provides electrical isolation from high-voltage conductors, protecting both operators and equipment.

Problems Solved by Rogowski Coils

Measurement of Large Currents: Traditional current transformers saturate at high currents, but Rogowski coils do not.

Capturing Fast Transients: Ideal for analyzing short-duration events such as surges and spikes.

Ease of Retrofitting: Can be installed without disconnecting circuits, saving downtime in industrial and utility environments.

Improved Power Quality Monitoring: Enables utilities and industries to track harmonics and prevent equipment damage.

Cost and Space Efficiency: Their lightweight, coreless design reduces cost and installation challenges.

Future Trends in Rogowski Coil Applications

As energy systems evolve, Rogowski coils are expected to play an even larger role in:

Smart Grid Monitoring: Integration with digital relays, SCADA systems, and IoT platforms for real-time current data.

Electric Vehicle Infrastructure: Used in fast-charging stations and onboard monitoring systems for accurate current measurement.

Renewable Energy Expansion: Essential for precise current monitoring in solar, wind, and hybrid energy systems.

Advanced Power Electronics: Growing demand for wide-bandgap semiconductors (SiC, GaN) in converters requires high-bandwidth current sensing solutions like Rogowski coils.

Portable Testing Equipment: Development of compact, clamp-on Rogowski coils for field engineers and technicians.

Conclusion

A Rogowski coil is a versatile, accurate, and safe solution for measuring AC currents in a wide range of applications. From high-voltage substations and industrial plants to renewable energy systems and laboratory research, it provides unmatched advantages such as wide bandwidth, flexibility, and immunity to magnetic saturation. By solving challenges in current measurement and adapting to new technologies, Rogowski coils are becoming indispensable tools in the transition toward smarter, cleaner, and more reliable energy systems.

As industries move toward digitalization and renewable integration, Rogowski coils will continue to expand their role, offering engineers and operators a powerful means of monitoring and controlling electrical currents in the modern energy landscape.