C37.110 guide for the application of current transformers used for protective relaying purposes

Conroy, Michael; Nelson, Bob; Bozoki, B.; Chadwick, J.W.; Drum, P.R.; Dovrak, L.L.; Hasenwinkle, I.; Huddleston, J.D.; Kotheimer, W.C.; Linders, J.R.; McDonald, Mike; Moskos, G.; Parr, G.C.; Ryan, Rita M.; Sage, E.T.; Smaha, D.W.; Stephen, K.A.; Stephens, J.E.; Uchiyama, J.; Zocholl, S.E.

doi:10.1109/61.736693

Cited by 36 publications

(2 citation statements)

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“…These problems can cause severe loss of production to various plants or damages to critical electrical equipment. The IEEE guide for the application of current transformers (IEEE Standard C37.110) contains steps to avoid the effects of AC and DC CT saturation [8]. However, many of these steps result in large CTs, which are not economically acceptable.…”

Section: Introductionmentioning

confidence: 99%

Saturation of Current Transformers and its Impact on Digital Overcurrent Relays

El-Amin

Al-abbas

2006

2006 IEEE/PES Transmission &Amp; Distribution Conference and Exposition: Latin America

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Improper selections of current transformers will result in CT's saturation during fault conditions which can affect protection relays operations. With the absence of clear and practical guidelines for CT's selections, designers are facing great difficulties to ensure proper operations of digital relays. The impact of CT saturation is different for different protection devices and schemes. This paper investigates the influence of CT saturation on over-current digital relays, in distribution systems where loads are relatively smalls and connected to switch-gears with high short circuit levels. A research was performed to verify the operations of instantaneous and time-delayed over-current digital relays to ensure coordination with other devices and safe isolations of faults. It is shown that instantaneous digital relays will perform properly with a relatively small CT's. A criterion for selecting CT's for instantaneous digital over-current relays operations is presented. However, time-delayed over-current relays will be significantly impacted by CT's saturation and special care shall be taken to achieve coordination with other devices.

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Section: Introductionmentioning

confidence: 99%

Saturation of Current Transformers and its Impact on Digital Overcurrent Relays

El-Amin

Al-abbas

2006

2006 IEEE/PES Transmission &Amp; Distribution Conference and Exposition: Latin America

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“…The saturation phenomenon may impair the reliability of CT if an appropriate alternative for saturation detection or correction is not applied to resolve the problem. A few approaches have been proposed to reduce the effect of CT satu-ration [13][14][15]. To measure the large current, a Rogowski coil is used, which is representative of several devices.…”

Section: Introductionmentioning

confidence: 99%

Electromotive Force Characteristics of Current Transformer According to the Magnetic Properties of Ferromagnetic Core

Kim¹

2015

Transactions on Electrical and Electronic Materials

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The most common structure of the current transformer (CT) consists of a length of wire wrapped many times around a silicon steel ring passed over the circuit being measured. Therefore, the primary circuit of CT consists of a single turn of the conductor, with a secondary circuit of many tens or hundreds of turns. The primary winding may be a permanent part of the current transformer, with a heavy copper bar to carry the current through the magnetic core. However, when the large current flows into a wire, it is difficult to measure its magnitude of current because the core is saturated and the core shows magnetic nonlinear characteristics. Therefore, we proposed a newly designed CT which has an air gap in the core to decrease the generated magnetic flux. Adding the air gap in the magnetic path increases the total magnetic reluctance against the same magnetic motive force (MMF). Using a ferrite core instead of steel also causes the generation of low magnetic flux. These features can protect the magnetic saturation of the CT core compared with the steel core. This technique can help the design of the CT to obtain a special shape and size.

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