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Parameter Description Of Current Transformer
Oct 26, 2017

Parameter description of current transformer

First, the type of current transformer:

First letter: L - current transformer

Second letters: A - through wall type; Z - pillar type; M - bus type; D - single turn through type; V - structure inverted type; J - zero sequence

Grounding detection; W - pollution resistance; R - winding bare type

Third letter: Z - epoxy pouring type; C - porcelain insulation; Q - gas insulation medium; W - special for microcomputer protection

Fourth letter: B - belt protection level; C - differential protection; D - D level; Q - strengthening type; J - strengthening type ZG

Fifth digit: voltage grade product serial number

Two. Main technical requirements

2.1 rated capacity: rated power consumed by two rated current through two rated load. Rated capacity can be expressed as apparent power V.A, or can be expressed by two times rated load impedance.

2.2 rated current: current load current through primary winding of current transformer. The current rating of current transformer used in power system is 5 ~ 25000A, and the precision current transformer used in test equipment is 0.1 ~ 50000A. The current transformer can operate under rated current for a long time. When the load current exceeds the rated current value, it is called overload, and the current transformer over load operation will burn out the winding or reduce the service life.

2.3 two rated current: the first induction current through the two winding of the current transformer.

2.4 rated current ratio (ratio): the first rated current and the two rated current ratio.

2.5 rated voltage: the maximum voltage that the primary winding can withstand for a long time (the effective value is kV) shall not be lower than the rated phase voltage of the connected line. Current transformer rated voltage is divided into 0.5, 3, 6, 10, 35110220330500kV and other voltage levels.

2.610% times: in two load and arbitrary power factor specified under the current error of current transformer for 10%, multiples of a current on the ratings. 10% multiples is the technical index related to relay protection.

2.7 accuracy level: the level of the transformer itself error (ratio and angular difference). The accuracy level of current transformer is divided into 0.001 to 1 levels, and the accuracy is greatly improved compared with the former.  Used in power plant, substation, electrical instrument electric control panel distribution units generally use 0.5 or 0.2; for relay protection equipment, the line is generally not less than 1; for electric energy metering, load capacity as measured according to procedures required to select or how much electricity (see 1).

2.8 ratio: the error of transformer includes two parts: the ratio and the angle difference. The ratio error is referred to as the symbol F, which is equal to the difference between the actual two current and the primary current converted to the two side, and the ratio of the primary current converted to the two side, expressed as a percentage.

2.9 angle difference: phase angle error, referred to as angular difference, is generally expressed by symbol Delta. It is the phase difference between the two current vector and the primary current vector after 180 degree rotation. It is stipulated that the two current vector is ahead of the primary current vector, and the delta is positive, and vice versa.

2.10 the thermal stability and the dynamic stability factor: power system fault, current transformer due to thermal effect caused by the huge current short-circuit current and electric power, current transformer should be able to withstand without damage to the ability, with the ability to withstand the thermal stability and dynamic stability of multiple representation. The thermal stability factor is the ratio of the current to the current rating of the current transformer which does not cause the current transformer to exceed the allowable limit in the thermal stable current 1s. The dynamic stability multiple is the ratio of the maximum current instantaneous value and the rated current that the current transformer can withstand.

Add: No.38 South Taoyuan Road, Yaozhuang Town,Jiashan County, Jiaxing City, Zhejiang Province, China
Contact person: Elva Zhuang&Sunny Ni