Case Study On Improvement Of Low Voltage Power Engineering Essay

Case Study On Improvement Of Low Voltage causality Engineering EssayThis case study allow fors investigations on low voltage position scattering dodging in terms of galvanic constitution design at INTEC Section 17 Shah Alam. It was conducted to ensure that the system utilize is viable where it could lead to reliable and economical diffusion of strength. Therefore, this project was foc utilize on 415V bird self-feeder tugboat where suggestion suffer be offered to amend the respected system design.Distribution system is a system built to go forth a means of economically and reliably distributing personnel from mavin, or occasionally more than one main location to a number of geographically dispersed load centres at bottom a defined site boundary 1. Low voltage power distribution system is the portion between primary feeder and utilization equipment. Therefore, the purpose of low voltage distribution is to distribute power to end user where at the same term providi ng safe conditions. Internatioanl Education College (INTEC) Section 17, Shah Alam is the place where this case study was carried. The low voltage distribution system applied at INTEC is conventional simple radial distribution system where the operation and expansion of the system are simple. However, problems occur as the power transformer (2000kVA 11kV/433V) is overheated and the parentages lengths insulant of unessential windings is melted due to overload. The system itself is quite old where feeder pillar used to allocate the power to specify load is quite congested where it bespeak some upgrade. Therefore, to tackle those problems regarding on low voltage distribution system, suggestions slew be offered to improve the system that meets the specifications of galvanical standard and at the same time satisfy the end users. Hopefully it can be additional information for the INTEC Facility Unit to subordinate the problems and upgrade the respected feeder pillar to provide saf e, economical and reliable power to the end users.OBJECTIVESThe objectives of this case study areTo obtain a relative information regarding on the low voltage power distribution system of INTEC.To observe the congested feeder pillar design and implementation at INTEC.To identify problems related to the congested feeder pillar.To propose for the gain of congested feeder pillar.METHODOLOGYThe case study of low voltage power distribution at INTEC was carried out based on the primer blood of information such as books, journals, articles and related electrical specifications by The Institute of Electrical and Electronic Engineer (IEE), Tenaga Nasional Berhad (TNB), Suruhanjaya Tenaga (ST) and Jabatan Kerja Raya (JKR). With cooperation of local Facility Unit of INTEC, observations of respected substation and feeder pillar have been done. Some photo and reading has been taken to visualize the respected problems regarding on the overheated transformer and congested feeder pillar. Therefor e, from those data, suggestions can be offered to overcome the problems and at the same time to improve the congested feeder pillar. Finally, for future study, opinions can raised for the further improvement of low voltage power distribution system.LOW VOLTAGE POWER DISTRIBUTION SYSTEMDistribution FeederFeeder is the distribution lines that carry power throughout the distribution system. Radial distribution feeders are characterized by having only single path for power to flow from the source (substation) to the consumer load. The distribution network is composed of the substations and the feeders that they supply.Feeders are composed of sections each function a purpose. The mainline is the backbone of the feeder and is typically a three-phase line generally designed for 400A nominal and 600A contingency loading. From this mainline, three-phase or single-phase laterals extend. Laterals are branches that are attached to the main line to serve loads, which can have laterals of thei r own. To protect mainlines from faults in the laterals, these are typically fused or switched by remote reclosers. common fig 1. electricity Supply Specification in MalaysiaThe most common configuration for feeders is a four-wire wye configuration one conductor for each of the three phases plus a unanimous multi-grounded neutral conductor. Nevertheless, less common configurations are three wire wye and delta configurations. Four-wire wye configurations are extensively used for their safety and easy fault protection 4-7. This circuit sign permits the use of under-rated voltage equipment by using phase-to-ground voltages, and fuse protection for ground faults.Feeder pillarFeeder lynchpin is the electrical compartment that consists of equipment that distributes power to the respected loads. It controls the replacement of load where at the same time provides protection to the distribution line. Conventional feeder pillar consists of busbar, circuit breaker, grounding protection and metering equipment.The loads can be calculated by (1) for single phase and (2) for three phase system where it is proportional to voltage (V), authorized (I) and angle between voltage and current ()P=VI cos . (1)P=3 VI cos . (2)By applying diversity factor, the load consumption should be less than the calculated rank from (1) or (2) where the same load go out not be used all the time. Diversity is the engineering principle that in any given installation, some of the attached loads will not be running at the same time instant as other loads 8. Therefore the maximum fill of loads can be obtained to ensure that the cable and protection used is viable throughout the system.The voltage drop of cable is affected by cable length (L), tabulated voltage drop (mV/A/m) and the design current (Ib) as shown in (3).v.d. (V) = (mV/A/m) L Ib/1000. (3)ProtectionMoulded Case Circuit Breaker (MCCB) is used to interrupt the current path during fault occurrence. It is applicable for TPN (Thr ee Phase and Neutral) cables while Miniature Circuit Breaker (MCB) has glare rating compared to MCCB and it is only applied for SPN (Single Phase and Neutral) line.Earthing of the feeder pillar will provide protection from leakage current to ensure the safety to human from the danger of electric shocks during examination or criminal maintenance.LOW VOLTAGE POWER DISTRIBUTION SYSTEM IN INTECINTEC HT Distribution SystemThe incoming supply for INTEC from TNB is 11kV. Then it is step down to 415V by 2000KVA distribution transformer. The overall HT simplified schematic draw of INTEC can be observed as belowFigure 2. Simplified schematic diagram for HT electrical system in INTECLow Voltage Distribution SystemNext, the focus will be at Pencawang Elektrik No.1 where observation is done at Feeder Pillar No.1. The schematic diagram of LV side from Pencawang Elektrik No.1 can be seen from Fig. 3. INTEC used radial distribution feeder since it requisite lower cost, easier fault current prot ection, lower fault current and easier voltage control.Figure 3. mutual savings bank schematic diagram of LV at Pencawang Elektrik No. 1Feeder PillarFeeder Pillar No.1 is located between Block B (Cafeteria) and Block A (Computer Lab). This feeder pillar was affiliated from MSB. The maximum current rating for the MCCB of incoming is 600A.CUsersuserDesktopINTECN8 Afdhalfeeder pillar 2.jpgFigure 4. Feeder Pillar No. 1This respected feeder pillar distributes power to Bengkel Seni, Futsal Court, Cafeteria and Compound Feeder Pillar (Fig. 5).Figure 5. Schematic diagram for Feeder Pillar No.1By applying the diversity factor, the value of protection and cable sizing shall fit the estimated load. TABLE.I shows the maximum load that the system can withstand at a time. The power at maximum demand is calculated using (2). The power factor is maintained at 0.85.TABLE I. LOAD AT supreme DEMANDLoadPower (kW)MCCB Rating (A)Bengkel Seni61.098100Futsal Court38.49263Cafeteria61.098100Compound Feeder Pillar48.87880(Estimated value of load at maximum demand in Feeder Pillar No. 1)From the existing load as tabulated above, the calculated nominal current is 341.363A using (2). Therefore the rated current of MCCB for the incoming is viable where the rated current of MCCB is 600A.The cables are connected to the busbar. Types of cables used is 4 core, 0.6/1kV, Copper Cable with creation termination. The cables are terminated to the busbar as pictured in Fig.6.CUsersuserDesktopINTECN8 Afdhalconnection 2.jpgFigure 6. Cables connection to the busbar.From the above figure, it can be observed that the cables connection quite messy where it is hard to indicate which cable is connected to their respected load. It is not labelled to identify the cable. If fault occurrence, it will took a time for the technician to accomplish maintenance due to the congested condition of the cable.The cable surface for each line can be seen from TABLE II.TABLE II . CABLE SIZINGTypeMCCB (A)Cable Size (mm2)2 x 4C XLPE6001851 x 4C XLPE100501 x 4C XLPE100501 x 4C XLPE80351 x 4C XLPE6325EarthingEarthing is purposely used to protect human from electric shock due to current leakage. Therefore this feeder pillar has the same earthing mechanism for safety reason.CUsersuserDesktopINTEC1-3-2011 Firdaus N701032011023.jpgFigure 7. Earthing of Feeder Pillar No.1From the fig. 7, all cables are terminated at the same point where it can provide easy path with a low resistance to earth and protect consumer from electric shock. However, those earth cables is not insulated which could lead to current leakage throughout the feeder pillar compartment in case the cable touch the wall of feeder pillar where it is made of steel (good conductor). Therefore, if such case happened it will cause electric shock to human who touch the feeder pillar.PROPOSED SYSTEMRadial Distribution System ImprovementBy referring back to the type of distribution feeder system approached at INTEC, radial type of distribution feeder is applied. Even though radial circuits are simpler to operate and maintain, in order to increase the reliability and power quality of distribution feeders, networked configurations must be used 458. However the installation cost of network system will be major obstacle where it required total modification of system. Therefore, primary loop radial distribution system can be applied to make the system more reliable.Figure 8. radical loop distribution systemFigure 9. Proposed MCBFig. 8 and 9 illustrate on how the system will look a comparable when improvement can be applied. The primary loop consists of two feeders which serve one or several loads. If one feeder fails, the normally open switch can be automatically (or manually) closed to feed the loads from the backup feeder, once the bad section has been sectionalized. This approach is very useful especially for underground cable system since the maintenance of underground cables is complex process that would create long interrupt ions if failure occurs.Feeder Pillar Proposed DesignFrom the Feeder Pillar No.1, suggestion can be offered to improve the system is upgrading the feeder pillar to MSB. By referring back to fig. 5, there were two loads that have circuit breaker rating of 100A TPN MCCB while in the MSB as in fig. 3 there were spare load that can be used. Therefore those two loads from Cafeteria and Bengkel Seni can be right off connected to MSB. By this action, the congested condition of feeder pillar can be solved.Figure 10. Upgrade of feeder pillar to MSBSome benefits can be obtained if the load of Bengkel Seni and Cafeteria is transferred to MSBIf fault occur at Feeder Pillar No. 1, those loads will not being interrupted. Therefore it promises the perseveration of power supply to the load.The voltage drop of each cable is shown in TABLE III.TABLE III. CABLE VOLTAGE DROPSize (mm2)mV/A/mLength (m)IbVoltage beading (V)1850.22100278.2416.12500.861081.840.708081.845.63351.151065.470.753251.6015049.10 11.784(Voltage drop of respected cable in the Feeder Pillar No.1)From TABLE III, it shows that the incoming cables itself occupy high voltage drop which is 6.12V for each cable. Then, if load of Bengkel Seni and Cafeteria is upgraded to MSB, the voltage drop can be observed from TABLE IV.TABLE IV. LOAD VOLTAGE DROPLoadCalculated Voltage Drop (V)Future Length (m)Future Voltage Drop (V)Percentage (%)Bengkel Seni11.7518012.673.05Cafeteria6.821107.7421.87(Future voltage drop if load of Bengkel Seni and Cafeteria is upgraded into MSB)Although the voltage drop risen up since the length of occupied cable is increased, the voltage can be reduce by replacing higher cross sectional area of the cable. However, the value of voltage drop is still within the specified value of allowed voltage drop 8.By connecting those loads to MSB, the existed feeder pillar will not be congested anymore. Those two loads that were directly connected to MSB will became spare and it can be used for future expansion of nearest building located near to the respected feeder pillar (refer fig. 11).Figure 11. Empty slot of loads acted as spareTherefore the future load will be based on TABLE V.LoadPower (kW)MCCB Rating (A)Futsal Court38.49263Compound Feeder Pillar48.87880SpareSpareThe total load at Feeder Pillar No.1 will be about only 70kW where the nominal current value from the incoming will be only 114.57V that could lead to only 2.52V of voltage drop.EarthingFor earthing cable, it is wise to insulate those cables with PVC insulator to avoid any electric shock due to current leakage. It must meet the electrical standard where earth cable must be insulated with green or green/yellow insulation based on fig. 12 6.http//www.china-wire-cable.com/photo/6654ca80a2286ebde6efb52e3ffbab88/Earth-Cable.jpgFigure 12. Proper insulation of earth cableComments and SuggestionThe project will become a wise step to ensure that the respected Feeder Pillar No. 1 will become a reliable where it can provide a contin uity of supply to a certain loads. However this project could not be implemented immediately since it will took period of time where maintenance underground cables is a complex task where it require skills and occupy more human power. In addition, the substation (PE No.1) need to be shutdown to perform the upgrade process where ironically the substation itself must distribute power to important places such as administration military position where it operates 24 hours a day and 7 days per week.Therefore it is recommended that this project must be implemented during the holiday where the total shutdown of PE No.1 can be done and the task of upgrade of the system can be performed by the respected party.CONCLUSIONFrom the case study that was carried out, it is necessary for Facility Unit of INTEC to cipher those suggestions in order to overcome any problems related to low voltage power distribution system.FUTURE STUDYSurge protection was integrated within the low voltage distribution system to protect the system from lightning strikes. For future study, the recommendation that can be offered to further the respected case study is to perform research on surge protection system in low voltage power distribution system in INTEC.ACKNOWLEDGEMENTThe author would like to express appreciation to his supervisor Ir. Harizan Che Mat Haris due to wise guidance and advices. For INTEC Facility Unit, the author felt pleasured to carry out this case study where he can affix his knowledge and gather more experience. Finally the author wants to offer his gratitude to people who was contributed toward the completion of this case study.