Investigation On Carbon Emission from Energy Usage at Universiti Tun Hussein Onn Malaysia

Carbon emissions are the primary contributor to global warming, and it is widely known that the emissions must be decreased significantly to avoid the worst effects of climate change. The objective of this study is to investigate the carbon emissions from energy usage at the Universiti Tun Hussein Onn Malaysia campus. The main data-gathering approach for this study is analyzing technical reports on energy usage from 2015 to 2021 collected at Development and Maintenance Centre (PPP) and Sustainable Campus Office (SCO). The acquired data were evaluated and compared over seven years in data presentation and analysis. According to the findings, the highest energy usage has a significant impact on the rising carbon emission levels on campus, with the maximum emissions occurring in 2015 with 1955.38 tCO2e and the lowest occurring in 2021 with 965.70 tCO2e. On the other hand, based on data collected, according to the building, from 2018 to 2020 the highest building in carbon emission was in 2018 demonstrated the highest carbon emission released by the Faculty of Technical and Vocational Education (FPTV) with 2,875 tCO2e. As a result, lower energy usage will lead to less carbon emissions that could provide a better environment, with less pollution and significantly lower cost

Partial discharge in medium and high voltage electrical devices

Partial discharges (PD) are small electrical sparks or pulses that occur within the insulation of medium and high voltage electrical devices. These pulses will partially bridge the gap between phase insulation to ground or phase to phase insulation. These discharges erode insulation and eventually result in insulation failure. There are three types of discharges for insulation that are internal discharges, corona and surface discharge

The insulation performance of novel refrigerant gas as an alternative to SF6 for medium voltage switchgear

Gas-insulated systems are widely utilized in the electric power sector to transmit and distribute electrical energy. Sulphur-hexafluoride (SF6) has dominated gas insulation in high-voltage insulation technology since the early 60s. It is a greenhouse gas with a protracted lifespan in the atmosphere. This paper proposes an economical and comparatively more environmentally friendly R507 gas alternative to SF6 for medium-voltage applications. R507 has been analyzed experimentally through power frequency breakdown and lightning impulse testing to validate the performance and theoretical concepts. R507 has a very low liquefication temperature of −46.7∘C , but it must still be mixed with buffer gases such as CO2, N2, or dry air to meet the diverse liquefaction temperature applications. Various field utilization factors under AC and lightning impulse voltages are used in the experiments, along with different electrode geometries, including sphere-to-plane and rod-to-plane (i.e., quasi-homogeneous and inhomogeneous electric field distribution). For comparison, identical experiments are conducted with pure SF6. R507 gas was found to be a promising substitute for SF6 gas, with its dielectric strength being approximately 0.95 times that of SF6 gas. A positive synergistic effect is present between R507 and CO2, along with the good self-recoverability property of the gas mixture. The current research study serves as a fundamental resource for characterizing the R507/CO2 gas mixture insulation properties to be utilized in practical applications

Investigation on the resonant oscillations in an 11kV distribution transformer under standard and chopped lightning impulse overvoltages with different configurations of shield placements

This paper presents an investigation on the resonant oscillations of an 11 kV layer-type winding transformer under standard and chopped lightning impulse overvoltage conditions based on calculated parameters. The resistances, inductances and capacitances were calculated in order to develop the transformer winding equivalent circuit. The impulse overvoltages were applied to the high voltage (HV) winding and the resonant oscillations were simulated for each of the layers based on different electrostatic shield placement configurations. It is found that the placement of grounded shields between layer 13 and layer 14 results in the highest resonant oscillation and non-linear initial voltage distribution. The oscillation and linear stress distributions are at the lowest for shield placement between the HV and low voltage (LV) windings

Classification of fault and stray gassing in transformer by using duval pentagon and machine learning algorithms

An oil-filled transformer should be able to operate for a long time with proper maintenance. One of the best diagnostic methods for oil-immersed transformer condition is dissolved gas analysis (DGA). However, there are times where the produce of stray gassing event might lead to fault indication in the transformer. Machine learning algorithms are used to classify the DGA data into normal condition and corresponding faults based on IEEE limits and Duval pentagon method. The algorithms that will be used include boosted trees, RUS boosted trees and subspace KNN, which belongs to the same ensemble group. Data resampling technique (SMOTETomek) is applied and shows further improvement on the accuracy of predictions by machine learning algorithms when deal with imbalance data. The algorithms are able to achieve the accuracy of 82.6% (boosted trees), 81.2% (RUS boosted trees) and 72.5% (subspace KNN), respectively, when validated with actual transformer condition

Effect of shield placement for transient voltage mitigation due to switching surges in a 33/11 kV transformer windings

This study presents an investigation on the effect of shield placement for mitigation of transient voltage in a 33/11 kV, 30 MVA transformer due to Standard Switching Impulse (SSI) and Oscillating Switching Impulse (OSI) surges. Generally, the winding and insulation in transformers could experience severe voltage stress due to the external impulses i.e. switching events. Hence, it is important to examine the voltage stress and identify the mitigation action i.e. shield placements in order to reduce the adverse effect to the transformer windings. First, the resistances, inductances, and capacitances (RLC) were calculated for disc type transformer in order to develop the winding RLC equivalent circuit. The SSI and OSI transient voltage waveforms were applied to the High Voltage (HV) winding whereby the transient voltages were simulated for each disc. The resulting voltage stresses were mitigated through different configurations of electrostatic shield placements. The resonant oscillations generated due to switching surges were analysed through initial voltage distribution. The analyses on the transient voltages of the transformer winding and standard error of the slope (SEb) reveal that the location of shield placement has a significant effect on the resonant switching voltages. The increment of the shield number in the windings does not guarantee optimize mitigation of the resonant switching transient voltages. It is found that the voltage stress along the windings is linear once a floating shield is placed between the HV and Low Voltage (LV) windings of the disc-type transformer under the SSI and OSI waveforms. These findings could assist the manufacturers with appropriate technical basis for mitigation of the transformer winding against the external transient switching overvoltage surges