Exchange Platform

Author: admin2012
Type: Model
Downloaded: 185 times
Date: 2018-12-11

DC Breaker

Description:
DC Breaker

Tag(s): Breaker

Author: h.gras
Type: Model
Downloaded: 428 times
Date: 2018-06-08

Vacuum Circuit breaker (VCB)

Description:
Three main characteristics of VCBs have been taken into account in the implemented model:
1. the chopping current value;
2. the cold withstand voltage characteristic (or cold gap breakdown v... see moreoltage);
3. the high frequency current quenching capability.

Ref: Transient Recovery Voltages in Vacuum Circuit Breakers Generated by the Interruption of Inrush Currents of Large Motors
A. Borghetti, F. Napolitano, C.A. Nucci, M. Paolone, M. Sultan, N. Tripaldi

Tag(s): Vacuum, circuit breaker, VCB,

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: AdminEMTP-RV
Type: Model
Downloaded: 376 times
Date: 2012-06-18

Ferro_hyst_Zno

Description:
Simple ferroresonance case. In this case the switching of a part of the network comprised of a cable connected to a no-load transformer is carried out. A pole of the breaker fails to open and an impor... see moretant and stable ferroresonance phenomena appears.
The ferroresonance problem, whether in a general circuit or in a power-system circuit, is usually tackled in one of two ways : circuit configuration (i.e series and/or parallel) or nonlinearities (i.e saturation and hysteresis of transformers). A fundamental factor to the occurence of ferroresonance is the nonlinear magnetizing characteristic of the transformer and the capacitive coupling.
In this case a 250 kVA, 20/0.4 kV transformer is used. This transformer is represented by the hysteresis transformer model. The hysteresis element has been used as the magnetization branch of the one-phase transformer model. A 200 m cable is used for the study. This cable is modelled by a PI-section. The short circuit power of the source is about 150 MVA.
In order to reduce overvoltages caused by ferroresonance, surge arresters are installed. Two questions have emerged : will the arresters mitigate ferroresonance, and will they fail during ferroresonance ? Simulations in different transient regimes can be carried out in order to determine the maximal current, overvoltages (voltage at the end of the cable for instance), energy absorbed by the arresters

Tag(s): Protection

Author: AdminEMTP-RV
Type: Model
Downloaded: 396 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