Why use current transformers in IoT systems

 

 

 

The reasons for using current transformers in IoT systems are mainly reflected in the following aspects:

 

 

 

 

 

1. Accurately measure current

 

High-precision conversion: Current transformers can convert the current in high-current lines into corresponding low-current signals through the principle of electromagnetic induction. This process maintains the proportional relationship between the currents, making the measurement more accurate.

Electrical isolation: Current transformers not only provide current conversion functions, but also achieve electrical isolation, protecting the measuring equipment from the direct impact of high voltage or high current, increasing the safety and reliability of the system.

 

 

 

 

 

2. Real-time monitoring and protection

 

Abnormality detection: By monitoring the output signal of the current transformer, the IoT system can quickly detect abnormal current, short circuit or overload conditions, and trigger protection devices in time to avoid damage to electrical equipment and systems or accidents.

Fault diagnosis: The data provided by the current transformer can also be used to identify faults in the circuit, providing information about the type and location of the fault, facilitating fault diagnosis and timely repair.

 

 

 

 

 

 

3. Energy management and optimization

 

Energy consumption analysis: Real-time current data provided by current transformers is an important component of energy management. It facilitates detailed energy consumption analysis to optimize the efficiency and reliability of power systems.

Load management: By monitoring the current information fed back by the current transformer, the IoT system can adjust the load distribution in real time to ensure the stable operation of the power system and avoid energy waste and equipment damage caused by overload.

 

 

 

 

 

 

 

4. Data integration and intelligent control

 

Data collection: Current transformers are one of the important nodes for data collection in IoT systems. The current data they provide can be collected, processed, and analyzed together with other sensor data in the system.

Intelligent decision-making: Based on the data provided by the current transformer, the IoT system can make more intelligent decisions, such as automatically adjusting the operating status of equipment, optimizing energy distribution, etc., to achieve more efficient energy utilization and smarter operation and maintenance management.

 

 

 

 

 

 

 

5. Adapt to various application scenarios

 

Wide application: Current transformers are suitable for various power systems, industrial automation, smart grids and other scenarios, providing flexible data collection and monitoring methods for the Internet of Things system.

High reliability: The current transformer can work stably in harsh working environments, such as high temperature, high humidity, strong electromagnetic interference, etc., ensuring the stability and reliability of the IoT system.

 

 

 

 

 

 

 

 

6. Specific application scenarios

 

Power system: Current transformers play a vital role in power systems. They are widely used in substations, distribution rooms, power plants and other places to measure the current in high-voltage lines and convert high currents into low currents for the use of electrical equipment such as transformers, energy meters, protection relays and automatic control devices. Through the accurate measurement of current transformers, current anomalies can be detected in time, thereby protecting the safe operation of equipment.

Communication system: In the communication system, current transformers are mainly used for lightning protection and anti-interference to ensure the stability and reliability of communication.

Computer room: Computers and other equipment have high voltage requirements, and current transformers are used for power monitoring and fault detection. They can reduce high currents to measurable or controllable low currents to ensure safe and stable operation of equipment, while improving the operating efficiency and safety of computer rooms.

Rail transit: Current transformers are also widely used in the field of rail transit, mainly for monitoring and controlling the contact network of trains. Through current transformers, high currents can be reduced to measurable or controllable low currents, ensuring the normal operation of the contact network of trains, and realizing remote monitoring and control, thereby improving the safety and reliability of rail transit.

Industrial Automation: In industrial production processes, current transformers are used to monitor and control the current of motors, detect abnormal motor operation in a timely manner, and avoid equipment failures and production accidents. In addition, they are also used in current feedback control systems to achieve precise control of motor speed and torque.

New energy field: Current transformers are used for current monitoring and control in photovoltaic power generation and wind power generation systems to ensure the stable operation of new energy equipment.

In summary, current transformers play a vital role in the Internet of Things system. They provide strong support for the stable operation and efficient management of the Internet of Things system through functions such as accurate current measurement, real-time monitoring and protection, energy management and optimization, data integration and intelligent control, and adaptation to various application scenarios.

 

This article will explain in detail one of the power metering device families – the current transformer.

 

 

 

 

Definition of Current Transformer

 

 

 

A current transformer is a device that can convert a large current on the primary side into a small current on the secondary side for measurement. Its interior is composed of a closed iron core and windings. The figure shows an overview of the interior of a current transformer. The left side has fewer coils, which are usually connected in series in the circuit where the current needs to be measured, called the primary side; the right side has more coils, which are usually connected in series in the loop of the measuring instrument (usually an ammeter).

 

 

 

 

 

 

Principle of Current Transformer

 

 

 

In power supply lines, the magnitude of primary (main) current varies greatly, ranging from a few amperes to tens of thousands of amperes. In order to facilitate measurement, protection and control, the primary current needs to be converted into a relatively uniform secondary current. In addition, the voltage on the primary line is generally high, and it is very dangerous to measure it directly.

 

The current transformer plays the role of current conversion and electrical isolation.

 

The winding of the current transformer connected to the measured current (the number of turns is N1) is called the primary winding (or primary winding, primary winding); the winding connected to the measuring instrument (the number of turns is N2) is called the secondary winding (or secondary winding, secondary winding). The current ratio of the primary winding current I1 of the current transformer to the secondary winding current I2 is called the actual current ratio K. The current ratio of the current transformer when working at the rated current is called the rated current ratio of the current transformer, which is represented by Kn.

 

 

For pointer-type ammeters, the secondary current of the current transformer is mostly in ampere level (such as 5A, etc.). For digital instruments, the sampled signal is generally in milliampere level (0-5V, 4-20mA, etc.). The secondary current of the micro current transformer is in milliampere level, and it mainly acts as a bridge between the large transformer and the sampling.

 

 

 

 

 

Classification of current transformers

 

 

 

Classification by purpose:

 

Measuring current transformer (or measuring winding of current transformer): mainly used to measure large current of alternating current and convert it into a more uniform current, so as to facilitate standardized measurement. This transformer plays a key role in electrical isolation, making it safe to directly measure the current and voltage on the line.

Protective current transformer (or protective winding of current transformer): usually used together with relay device. When a line fault occurs, it will send a signal to the relay device, thereby cutting off the circuit and protecting the power supply system.

Classification by insulating medium:

 

Dry-type current transformer: ordinary insulating material is used as insulation after being treated with varnish.

Cast current transformer: cast with epoxy resin or other resin mixed materials.

Oil-immersed current transformer: It is insulated by insulating paper and insulating oil, generally an outdoor type, and is commonly used in various voltage levels in my country.

Gas insulated current transformer: Its main insulation is made of gas.

Classification by installation method:

 

Through-type current transformer: used to pass through a panel or wall.

Pillar type current transformer: installed on a plane or pillar, and can be used as a primary circuit conductor pillar.

Bushing type current transformer: There is no primary conductor and primary insulation, and it is directly sleeved on the insulating bushing.

Busbar current transformer: It has no primary conductor but primary insulation and is directly mounted on the busbar for use.

 

 

 

 

Selection parameters of current transformer

 

 

 

The selection parameters of current transformer mainly include the following aspects:

 

Rated current: refers to the current value of the current transformer under long-term normal operation under design conditions. When selecting, ensure that the actual operating current is within the range of 20%~120% of the rated current to ensure the stability of the transformer.

Rated voltage: indicates the maximum operating voltage that the transformer can withstand. When selecting, make sure that the voltage value matches the system voltage.

Load requirements: When selecting a current transformer, you also need to consider the load requirements of the downstream equipment. For example, if the downstream is a protection device or meter, you need to ensure that the selected transformer can provide enough current to meet the normal working requirements of these devices.

Output signal, frequency range, rated load, division accuracy and withstand voltage: These are also key parameters that need to be considered when selecting a current transformer, which will directly affect the performance and use of the transformer.

--- END ---