Electronic Current Transformer

The principle of current transformer is based on the principle of electromagnetic induction. The current transformer consists of a closed core and winding. The number of turns in the primary winding is very small, and it is strung in the current line that needs to be measured, so it often has all the current flowing through the line, and the number of turns in the secondary winding is relatively large, and it is connected in the measuring instrument and the protection loop. When the current transformer is working, its secondary loop is always closed, so the impedance of the series coil of the measuring instrument and the protection loop is very small. The working state of the current transformer is close to the short circuit.

Support for drawing customization

According to different uses, current transformers can be roughly divided into two categories:

Measuring current transformer (or measuring winding of current transformer): within the normal working current range, to provide the current information of the power grid to the measuring and metering devices.

Protection current transformer (or protection winding of current transformer): in the state of power grid fault, to provide relay protection and other devices with power grid fault current information.

Original: Wuxi, Jiangsu, China

Certification: ISO9001,CE, ISO14001, OHSAS18001 etc.

Price: Negotiable

Material: Skeleton, magnetic core, enameled wire, insulation tape, etc

Voltage: 380V 50Hz, the voltage can be as local demand

Payment term: TT, LC

Delivery date: Negotiable

Packing: export standard

Market: Middle East/ Africa/Asia/South America/Europe/North America

Warranty: 1 year

MOQ: 1 set

Main technical requirements

Rated capacity: The apparent power consumed when the rated secondary current passes through the rated secondary load. Rated capacity can be expressed in terms of apparent power V.A, or in terms of secondary rated load impedance Ω.

Primary rated current: The load current allowed to pass through the primary winding of the current transformer. The primary rated current of the current transformer for the power system is 5 ~ 25000A, and the precision current transformer for the test equipment is 0.1 ~ 50000A. The current transformer can run for a long time at a rated current. When the load current exceeds the rated current value, it is called overload. Long-term overload operation of the current transformer will burn the winding or reduce the service life.

Secondary current rating: The primary induced current is allowed through the secondary winding of the current transformer.

Rated current ratio (variable ratio): the ratio of primary rated current to secondary rated current.

Rated voltage: The maximum voltage that the primary winding can withstand to the ground for a long time (the effective value is in kV), which should not be lower than the rated phase voltage of the connected line. The rated voltage of the current transformer is divided into several voltage levels such as 0.5, 3,6,10,35,110,220,330,500 kV.

10% multiple: The multiple of the primary current to the rated value when the current error of the current transformer is -10% under the specified secondary load and any power factor. The 10% multiple is a technical index related to relay protection.

Accuracy grade: indicates the grade of the transformer's error (ratio and Angle difference). The accuracy level of the current transformer is divided into 0.001 ~ 1 various levels, and the accuracy is greatly improved compared with the original. Electrical instruments used in power plants, substations, and power units on the distribution control panel are generally 0.5 or 0.2; For equipment, line relay protection is generally not less than 1 level; When used for power metering, depending on the measured load capacity or electricity consumption according to the requirements of the regulations to choose (see the first lecture).

Ratio difference: the error of the transformer includes two parts: ratio difference and Angle difference. The ratio error, referred to as the ratio difference, is generally expressed by the symbol f, which is equal to the difference between the actual secondary current and the primary current converted to the secondary side, and the ratio of the primary current converted to the secondary side, expressed as a percentage.

Angle difference: the phase Angle error is referred to as the Angle difference, generally expressed by the symbol δ, which is the phase difference between the secondary current vector and the primary current vector after rotation 180°. It is specified that the secondary current vector ahead of the primary current vector δ is positive, the reverse is negative, and minute (') is used as the calculation unit.

Thermal stability and dynamic stability were multiple: When the power system fails, the current transformer is subjected to the thermal effect and electrodynamic effect of the huge current caused by the short-circuit current, and the current transformer should be able to withstand without being damaged. This ability is expressed by the thermal stability and dynamic stability multiple. The thermal stability ratio is the ratio between the current that does not cause the heat of the current transformer to exceed the allowable limit within 1s of the thermal stability current and the rated current of the current transformer. The dynamic stability factor is the ratio of the maximum instantaneous current that the current transformer can withstand to its rated current.

Hot Tags: electronic current transformer, China electronic current transformer manufacturers, suppliers, factory, Zero Sequence Current Transformer, Current Transformer CT