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Author: n.sene
Type: Publication
Date: 2015-04-01

Transient recovery voltages in vacuum circuit breakers generated by the early-interruption of the inrush current of large motors

Description:
The switching of medium voltage electrical motors is typically realized by means of vacuum circuit breakers (VCBs) essentially in view of their elevated number of switching cycles. As known, switching... see more of VCBs generates important transient recovery voltages (TRVs)
that need to be properly evaluated in both VCB sizing and in the power system insulation coordination. As large medium voltage electrical motors are installed into plants typically controlled by means of Supervisory Control And Data Acquisition (SCADA) systems,
maneuvers that involve the motor inrush followed by its sudden de-energization (due, in general, to the intervention of an automatic diagnostic function), resulting into important TRVs, are not unusual. The paper aims at investigating the TRVs due to this specific type of
VCB switching by means of a model implemented in the EMTP-RV simulation environment. By making reference to a real plant, the validation of the implemented models is obtained by comparing the simulation results with some experimental transients provided by the plant data fault recorder. The paper finally discusses the adequacy of different countermeasures by analyzing their effectiveness for the TRVs limitation.

Authors: A. Borghetti, F. Napolitano, C.A. Nucci, M. Paolone, M. Sultan, N. Tripaldi

CIGRE - International Symposium “Assessing and Improving Power System Security, Reliability and Performance in Light of Changing Energy Sources” Recife, Pernambuco, Brazil, April 3-6, 2011
Topic 3 – System technical performance
Subtopic 3.5 – Switching and lightning transient on power systems. Impact on performance and measurements

Tag(s): Transient recovery voltages, vacuum circuit breakers, motor inrush currents, EMTP simulations

Author: n.sene
Type: Publication
Date: 2015-04-01

Continuous-Wavelet Transform for Fault Location in Distribution Power Networks: Definition of Mother Wavelets Inferred From Fault Originated Transients

Description:
The paper presents a fault location procedure for distribution networks based on the wavelet analysis of the fault-generated traveling waves. In particular, the proposed procedure implements the conti... see morenuous wavelet analysis applied to the voltage waveforms recorded during the fault in correspondence of a network bus. In order to improve the wavelet analysis, an algorithm is proposed to build specific mother wavelets inferred from the fault-originated transient waveforms. The performance of the proposed algorithm are analyzed for the case of the IEEE 34-bus test distribution network and compared with those achieved by using the more traditional Morlet mother wavelet.

Authors: Alberto Borghetti, Senior Member, IEEE, Mauro Bosetti, Mauro Di Silvestro, Carlo Alberto Nucci, Fellow, IEEE, and Mario Paolone, Member, IEEE

IEEE TRANSACTIONS ON POWER SYSTEMS, VOL. 23, NO. 2, MAY 2008

Tag(s): Continuous wavelet transform, distribution network, EMTP simulations, fault location, mother wavelet, power quality.

Author: e.rutovic
Type: Example
Downloaded: 1332 times
Date: 2013-02-20

JavaScript Examples

Description:
Some simple EMTP-RV scripts :
- Parameters sweep
- Change the simulation options
- Run simulation
- Change the fault location
- Change the transformer remanent flux
- Cha... see morenge the switching Times

Tag(s): Script, Javascript

Author: AdminEMTP-RV
Type: Model
Downloaded: 466 times
Date: 2012-06-18

CB_arc_CM

Description:
This is an interesting case of the study of arc-circuit interaction in case of the interruption of a short-line fault.The arc is represented by a composite Cassie-Mayr model and the line is represente... see mored as frequency-dependant.
The case shows the application of black-box arc modeling in the study of kilometric-line fault capability of a 420 kV circuit-breaker. By zooming on the arc current and voltage near current-zero, post-arc current and initial TRV may be visualized in both cases of clearing and thermal failure.

Tag(s): Example, Protection

Author: AdminEMTP-RV
Type: Document
Downloaded: 913 times
Date: 2012-06-18

Look what happens without EMTP-RV

Description:
This is a nice video about the switching of a shunt reactor (most probably 500 kV) with a Circuit-Switcher.
>A circuit-switcher is a SF6 load-break swith with no fault current breaking cap... see moreability. The load current, in this case around 150 A, is normally interrupted first by the 2 interrupters and then the disconnect will open to isolate the reactor.
What happened in this video:
1 - During the opening, an external flashover occurs on one of the chamber most probably because of the contamination;
2 - The other chamber can not withstand the whole voltage and reignites internally;
3 - The external flashover vanishes because an arc is established inside;
4 - The disconnect opens on the full load current;
5 - The arc burns freely in the air for some 10 seconds until it is self-extinguished or eliminated by a circuit-breaker operation.

Tag(s):