The role of current transformers on low-voltage outgoing circuits

  Distribution cabinets refer to electrical products used for power generation, transmission, distribution, power conversion and consumption in power systems, which play the role of switching, control or protection, and the voltage level is 3.6kV~550kV. They mainly include high-voltage circuit breakers, high-voltage disconnectors and grounding switches, high-voltage load switches, high-voltage automatic reclosing and sectionalizers, high-voltage operating mechanisms, high-voltage explosion-proof distribution devices and high-voltage switch cabinets. The high-voltage switch manufacturing industry is an important part of the power transmission and transformation equipment manufacturing industry, and occupies a very important position in the entire power industry.
Distribution cabinets refer to low-voltage switch cabinets with all sides closed except the installation surface. The electrical components such as switches, protection and monitoring control of this cabinet are install in a close casing made of steel or insulating materials, which can be install against the wall or away from the wall. There can be no isolation measures between each circuit in the cabinet, or it can be isolate by grounded metal plates or insulating plates. Usually the door and the main switch operation are mechanically interlock. There are also protective table-type switch cabinets (i.e. control consoles), on which control, measurement, signal and other electrical appliances are install. Protective switch cabinets are mainly use as power distribution devices at process sites.

Current transformers are a commonly use electrical equipment in power distribution cabinets. In the combination process of power distribution cabinets, they play their due role. Simply put, current transformers convert large currents into small currents for measurement and protection purposes. For example, 300/5 converts a large current of 300A into a small current of 5A. Generally speaking, 300A is call primary current and 5A is call secondary current. Why is it convert to 5A? This is an industry requirement based on instrument measurement requirements. So what is the role of current transformers in power distribution cabinets?
The role of current transformers in power distribution cabinets is to convert large currents into small currents. In the power system, current metering and some current protection are require, and the primary current will generate a large current of hundreds of amperes or even thousands of amperes. If such a large current needs to be measure, it will be a test for the metering equipment, which is technically difficult to achieve. In addition, introducing such a large current into the metering equipment in the power distribution room will undoubtedly pose a great safety hazard to the operator’s operating safety. Therefore, a current transformer is need to convert a large primary current into a small current for measurement and protection purposes.
The current transformer in the distribution cabinet can be connect to a metering ammeter to measure the actual current on the primary line. It can also be connect to protection equipment, such as an inrush current device to achieve inrush current protection. It can be connect to the tripping coil to play a tripping protection action when the current starts to rise, so as to protect the line and equipment.

The role of current transformers on low-voltage outgoing circuits

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