G. Amjad Hussain

The Smart Solution for the Prediction of Slowly Developing Electrical Faults in MV Switchgear Using Partial Discharge Measurements

An electrical fault in switchgear results in interruption of power supply, damage to equipment, and poses a hazard to personnel. This paper focuses on the detection of slowly developing faults leading to internal arc, using online monitoring technologies in medium-voltage switchgear. Unconventional radio-frequency (RF) techniques for discharge measurement are highly attractive but have not been widely applied in the industry due to their ineligibility to quantify actual discharge. On the basis of various benefits, a new application of a differential electric field ( D-dot) sensor for partial-discharge (PD) measurements has been introduced in this paper. The reliability of the sensor has been confirmed through comparison with a commercial high- frequency current transformer. An attempt has been made to quantify the apparent charge of online PD measurements. The energy of signal captured by the D-dot sensor has been compared with the apparent charge quantity calculated from current pulse measured by the conventional method. A second degree polynomial relation exists between the cumulative energy and apparent charge. It has been shown that when apparent charge is plotted against the cumulative energy of the RF signal for a number of pulses, defects can be separated on the basis of cluster positions within the scatter plot.

Integration of online proactive diagnostic scheme for partial discharge in distribution networks

Partial discharge (PD) diagnostic is considered as the main concern while making condition assessment plan for medium voltage assets. PD detection and localization in multi-section (straight and branched power lines) MV network is difficult by using the conventional Time Domain Reflectometry and Time Difference of Arrival methods. It is due to interconnected cables of different lengths and properties which make the interpretation of PD signals quite complex as compared to single cable routes. This paper presents an online technique of PD localization in MV cable network. PD activity emits current pulses propagating away from the PD site. Polarity of the detected PD pulses with reference to polarity of the supply voltage determines the direction of arrival of these pulses. Comparison of the polarity of PD pulses identifies the faulty section of the overhead covered conductor line as well as the cable network. A detailed discussion has been presented to address the practical issues of sensor implementation and polarity comparison in order to ensure the accuracy of polarity based direction of arrival (DOA) assessment during field application. Evaluation of DOA is based on directionally calibrated sensors. Allocated induction sensors are employed along the feeder for integrated implementation of proposed technique in accordance with the distributed agent for improving the network reliability.

Preemptive Arc Fault Detection Techniques in Switchgear—Part III: From the Laboratory to Practical Installation

The major types of slowly developing faults, which can lead to arc faults in switchgear and controlgear, such as partial discharge, arcing, and heating due to poor connections, can now be successfully detected and monitored. In parts I and II of this paper series, a detailed review of the immediate causes of arc faults, along with an overview of preignition and postignition methods for its mitigation, was presented. Various hybrid nonintrusive sensors were developed in the laboratory to implement preignition detection techniques. The major types of slowly developing electrical faults were created in the laboratory, and the sensors were employed to evaluate their performance along with an effective signal processing technique. Part III of the work is based on the successful performance of the sensors outside of laboratory conditions. Hybrid sensors have been installed in a real-world application, i.e., switchgear located in substations. This paper presents interesting results about this practical application and includes valuable discussion on the performance evaluation of different sensors, which further justifies the usefulness of the new sensors for online condition monitoring of switchgear, controlgear, and cable termination boxes. The implementation of this technology in industry may provide promising results in avoiding major accidents such as arc-flash in the switchgear and controlgear.

New pre-emptive arc fault detection techniques in medium voltage switchgear and motor controls

For Forest Products based industries, the significant benefits of pre-emptive arc-flash protection and online condition monitoring of electrical equipment are not well known. This paper provides a summary the research surrounding the development and testing of new advanced sensor technologies for this purpose. More extensive and detailed measurements, regarding significant defects leading to an arc flash event, have been completed since the first portion of the research was completed [1]. Early detection of impending faults and the prediction of future arc-flash occurrences in medium voltage (MV) switchgear and motor control centers (MCC) can be very beneficial. The development of new sensor technologies, both for partial discharge (PD) measurement and thermal detection, are discussed and evaluated. The two most common non-contact causes leading to an arc-flash event in MV switchgear and MCC are insulation degradation and thermal stresses. This paper will highlight very detailed results measured under both of these conditions in the laboratory and actual installed conditions. An effective signal processing method, used for extracting the essential indication data and the integration of this system into an existing protection PLC or SCADA, are outlined.