Evaluation of controlled energisation of an unloaded power transformer for minimising the level of inrush current and transient voltage distortion using PIR‐CBs

Bhatt, Kunal A.; Bhalja, Bhavesh R.; Parikh, Urmil

doi:10.1049/iet-gtd.2017.1825

Cited by 16 publications

(3 citation statements)

References 17 publications

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“…Long transmission cables are energised in these applications and, often, shunt reactors are also installed [53]. CB PIRs are also sometimes used in AC transmission systems when energizing unloaded power transformers [4,54,55].…”

Section: Circuit Breaker-pirsmentioning

confidence: 99%

Voltage transient management for Alternating Current trains with vacuum circuit breakers

Moore

Schmid

Tricoli

2021

IET Electrical Syst in Trans

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Alternating current power supplies and rolling stock with 25 kV (50 or 60 Hz) and 15 kV (16.7 Hz) traction systems do not have the characteristics and behaviour of a typical three-phase medium-voltage distribution system. Switching inductive loads with a vacuum circuit breaker (VCB) in MV traction systems poses familiar challenges as well as some unique challenges, such as the crossing of phase change neutral sections. Transformers represent highly inductive loads due to their iron core and, thus, the consequences of energizing and disconnecting a transformer and dealing with the energy stored in its inductance must be considered within a system context. The authors of this study consider two transient phenomena associated with switching single-phase, medium voltage, AC traction transformer loads using a VCB on railway rolling stock: (i) switching transients that occur when disconnecting a transformer, particularly if lightly loaded and (ii) pre-ignition and current inrush that occurs when energizing a transformer. Both phenomena can cause reliability problems, requiring increased system maintenance or resulting in premature failures of system components. The authors review the use of controlled switching and other state-of-the-art methods to prevent or limit voltage transients when switching a transformer load by means of a VCB. The effective application of such techniques has been demonstrated in previous research or established in practical applications by manufacturers and electrical distribution network companies.This is an open access article under the terms of the Creative Commons Attribution-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited and no modifications or adaptations are made.

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Section: Circuit Breaker-pirsmentioning

confidence: 99%

Voltage transient management for Alternating Current trains with vacuum circuit breakers

Moore

Schmid

Tricoli

2021

IET Electrical Syst in Trans

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“…Transformer energization at random instant creates unbalances in current and grid voltage due to inrush phenomena. Attaining steady state may take a number of seconds to some minutes based on X/R ratio of the system [11]. There are several factors affecting the magnitude of inrush current but level of residual flux and point of voltage wave at the time of energization are prominent one [12].…”

Section: A Transformer Energization and De-energizationmentioning

confidence: 99%

Evaluation of Natural de-Magnetization of Power Transformer Due to Capacitor Interaction with Area Under the Curve Method

et.al.¹

2019

IJCDS

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Transformer energization at random point presents inrush phenomena and is unfavorable for equipment due to high magnitude asymmetric current flow. These asymmetric currents are largely affected by level and polarity of residual flux presents in transformer core post its de-energization. Controlled switching technology is widely used to limit inrush current. Moreover, ignorance of residual flux would yield only moderate level of inrush current. Also, inaccurate estimation of de-magnetization status leads to improper estimation of energization instants during independent pole switching and the resulting inrush currents could not be reduced below desired level. Therefore it is quite important to know the exact level of residual flux post every de-energization operation of power transformer. Presence of capacitor bank, filter banks and connected XLPE cables offer natural de-magnetization of power transformers. The de-magnetization is categorized in no, partial and full de-magnetization. This paper presents novel approach for detection of natural de-magnetization of Power Transformer using load side measurements. Numerical integration has been used for the evaluation. Suggested method has been verified from field data collected from power transformers of different design and connection configuration across globe used for various grid voltage levels. Lastly, the effect of variation in sampling rate and level of residual fluxes is analyzed and the suggested method is found to be equally effective for said variations. The categorization of natural de-magnetization play important role in deciding energization instant for next switching of transformer

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“…Recently, controlled switching is more popular to be used in switching capacitor banks [7, 8]. The significant advantages of controlled switching of capacitor banks are in the limitation of inrush current amplitudes, reduction of switching overvoltage, protection of power equipment from dielectric failures and reduction of the maintenance frequency of VCBs [9]. The limitation of inrush currents during capacitive making operations is achieved by precise controlment of the switching instant according to the voltage between individual poles of VCB [10].…”

Section: Introductionmentioning

confidence: 99%

Capacitive making of double‐break vacuum circuit breaker: Transverse magnetic field contacts are superior to axial magnetic field contacts

Geng

Chen

Yao

et al. 2022

IET Generation Trans & Dist

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Previous studies mainly focused on the behaviours of single‐break vacuum circuit breakers (VCBs) in switching capacitor banks. The prestrike characteristics of double‐break VCBs subjected to axial magnetic fields (AMFs) and transverse magnetic fields (TMFs) in capacitive making operations, to find a proper structure of double‐break VCBs for capacitive switching are experimentally investigated here. Special attention is given to the prestrike gap, inrush current interruption, prestrike voltage, prestrike electric field strength and erosion on contact surfaces of double‐break VCBs. The results show that the 50% prestrike gap d50 and the scatter in prestrike gaps are significantly reduced by nearly 50% by the TMF double‐break VCB compared with the AMF double‐break VCB. The 50% prestrike arcing time ta50 of the TMF double‐break VCB can be reduced by 37.0% compared with the AMF double‐break VCB. The voltage distribution ratio between two vacuum interrupters (VIs) is more balanced in the TMF double‐break VCB (6:4) than in the AMF double‐break VCB (7:3) when prestrike occurs. The TMF double‐break VCB can reduce the erosion caused by inrush currents on contact surfaces compared with the AMF double‐break VCB. In switching capacitor banks, the TMF double‐break VCB is superior to the AMF double‐break VCB.

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Evaluation of controlled energisation of an unloaded power transformer for minimising the level of inrush current and transient voltage distortion using PIR‐CBs

Cited by 16 publications

References 17 publications

Voltage transient management for Alternating Current trains with vacuum circuit breakers

Voltage transient management for Alternating Current trains with vacuum circuit breakers

Evaluation of Natural de-Magnetization of Power Transformer Due to Capacitor Interaction with Area Under the Curve Method

Capacitive making of double‐break vacuum circuit breaker: Transverse magnetic field contacts are superior to axial magnetic field contacts

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