Secure application of transformer differential relays for bus protection

Thompson, Michael J.; Folkers, R.; Sinclair, A. M.

doi:10.1109/cpre.2005.1430430

Cited by 13 publications

(6 citation statements)

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“…RB is the burden resistance. Keep in mind that the connection of CTs and the fault type determine the multiplying factors for lead and relay impedances in the burden calculation [5].…”

Section: Ct Saturationmentioning

confidence: 99%

Paralleling CTs for line current differential applications: Problems and solutions

Costello¹,

Young²,

Traphoner³

2015

2015 68th Annual Conference for Protective Relay Engineers

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Paralleling current transformers (CTs) is a common practice in differential or line protection applications where the number of CTs exceeds the number of relay current inputs. This is especially true of line current differential applications applied to breaker-and-a-half and ring-bus configurations. This paper discusses complications that can arise from this practice and highlights relay design improvements that have been made to add security to these applications. Real-world event reports are shown to illustrate problems and solutions.

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“…RB is the burden resistance. Keep in mind that the connection of CTs and the fault type determine the multiplying factors for lead and relay impedances in the burden calculation [5].…”

Section: Ct Saturationmentioning

confidence: 99%

Paralleling CTs for line current differential applications: Problems and solutions

Costello¹,

Young²,

Traphoner³

2015

2015 68th Annual Conference for Protective Relay Engineers

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“…The volts per turn of a given CT is a function of the iron in the core of that CT. We return to our 345 kV, 20 MVA reactor example. Reference [11] provides detailed instructions on how to use (1). The reader is encouraged to use the information in [11] to reproduce the results presented here.…”

Section: B Criterion 2 -Prevent Asymmetrical Saturation On Switchingmentioning

confidence: 99%

“…Reference [11] provides detailed instructions on how to use (1). The reader is encouraged to use the information in [11] to reproduce the results presented here.…”

Section: B Criterion 2 -Prevent Asymmetrical Saturation On Switchingmentioning

confidence: 99%

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Practical EHV reactor protection

Basha¹,

Thompson²

2013

2013 66th Annual Conference for Protective Relay Engineers

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Shunt reactors are applied to long, high-voltage transmission lines to offset the impact of line charging capacitance to prevent high voltage during lightly loaded conditions. Shunt reactors are becoming more prevalent associated with the construction of long transmission lines to connect remote wind energy sources to load centers. During conditions when wind generation is at a minimum, the system is more likely to need reactive compensation to control high voltage on the transmission system. It can be difficult to design a protection system that provides adequate sensitivity to the extremely low levels of fault current for in-zone reactor faults, especially turn-to-turn faults, while remaining dependable for high-level terminal faults that are not limited by the impedance of the reactor. Current transformer (CT) selection criteria must balance sensitivity with performance during switching and internal faults. Often, standard equipment ratings put further restrictions on CT sizing selection. This paper discusses the different reactor types currently used, their characteristics, CT selection and performance issues, and different types of reactor faults. The paper also provides guidelines to practicing engineers to evaluate reactor protection design and determine protection elements and relay settings for a high-voltage transmission line shunt reactor. The discussion of various factors that affect the sensitivity and dependability of the protection elements helps in understanding the challenges encountered while determining relay settings. Detailed examples of CT performance calculations and guidelines are provided for protection element settings calculations.

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“…Relays with a dual-slope characteristic may be used to further mitigate the effects of CT saturation at higher fault currents. Empirical methods are available to determine characteristic slope settings adequate for preventing inadvertent operation during external faults with CT saturation on the faulted circuit CT [5] [6].…”

Section: Ct Performance Requirementsmentioning

confidence: 99%

Considerations for using high-impedance or low-impedance relays for bus differential protection

Behrendt¹,

Costello²,

Zocholl³

2010

2010 63rd Annual Conference for Protective Relay Engineers

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Two drastically different types of differential relays, one with a single set of very high-impedance inputs and another with multiple sets of low-impedance inputs, are available for bus differential protection. Protection engineers often question which type to choose for their bus protection applications. This paper discusses for each type of relay the concepts used, the pros and cons, and the importance that current transformer selection plays in applications.

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Secure application of transformer differential relays for bus protection

Cited by 13 publications

References 0 publications

Paralleling CTs for line current differential applications: Problems and solutions

Paralleling CTs for line current differential applications: Problems and solutions

Practical EHV reactor protection

Considerations for using high-impedance or low-impedance relays for bus differential protection

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