![International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD26574 | Volume – 3 | Issue – 5 | July - August 2019 Page 1163
Lightning arrester and instrumenttransformers(CTandPT)
are equipped at the incoming line and outgoing line of
substation. Without equipping the instrumenttransformers,
the substation may be damaged because of overcurrent and
overvoltage. So, it is important to have right current and
voltage rating of CT and PT for different lines.
Numbers of shed, minimum creepage distance, dry arcing
distance and diameter are differ according to its rating. In
this paper, the efficiency and design of LA, the peak voltage
rating of each arrester at 132 kV is 118.6 kV, creepage
distance is 2904 mm and maximum continuous operating
voltage is 94.88 kV. The creepage distance of current
transformer and potential transformer at 132 kV are 4065
mm.
6. ACKNOWLEDGEMENTS
The author deeply wants to express special appreciation
and heart-left thanks to Dr. Yadana Aung, Professor and
Head the Department of Electrical Power Engineering,
Technological University (Mandalay) for her willingness to
share her ideas and helpful suggestions on this paper writing.
7. REFERENCES
[1] [15 Tun] Tun Naing, "Potential Transformer and
Surge Arrester", 2015.
[2] [14 Ano] IEC, "Potential Post Insulators", 2014.
[3] [14 Lig] Ligong Gan, P-Eng Transmission
Engineering (AESO), "Insulation coordination in the
Alberta Interconnected Electric System", 2014.
[4] [13 Koo] Koos Holtzhyousen and Dr WL Vosloo,
"High Voltage Engineering Practice and Theory",2013.
[5] [12 Ano] Anony mous, "3Fl Silicons long Rod
Insulators for Transmission Lines 69-500 kv", 2012.
[6] [12 Ank] AnkaRa Seramik, "Outdoor Solid Core Post
Insulator", 2012.
[7] [00 Zae] Zaengl, W.S and E-kuttel, "High Voltage
Engineering Fundamentals", 2nd [Ed] J.kuttel (2000).
[8] [95 Fun] Funchiron, "Overvoltages and insulation
coordination in MV and HV", 1995.
[9] [93 IEC] IEC, "Station Post Insulators", 1993.
[10] [92 IEC] IEC, "CompositeInsulatorsforACOverhead
Lines With Nominal Voltages Larger Thon 1000 V -
Annexure C", 1992.
[11] [88 Loo] Looms, J.S.T, "Insulators for HighVoltages",
Peter Peregriness, London, 1988.
[12] [86 IEC] IEC, "Guide for the SelectionofInsulatorsin
Respect of PollutedConditions",IECRecommendations
Publication 815, 1986.](https://image.slidesharecdn.com/221studyandanalysisofinsulatorusedinsubstation-190912051613/85/Study-and-Analysis-of-Insulator-used-in-Substation-4-320.jpg)
Study and Analysis of Insulator used in Substation
- 1. International Journal of Trend in Scientific Research and Development (IJTSRD) Volume 3 Issue 5, August 2019 Available Online: www.ijtsrd.com e-ISSN: 2456 – 6470 @ IJTSRD | Unique Paper ID – IJTSRD26574 | Volume – 3 | Issue – 5 | July - August 2019 Page 1160 Study and Analysis of Insulator used in Substation Hnin Yu Lwin, U Hla Myo Htay Lecturer, Electrical Power Department, Technological University, Mandalay, Myanmar How to cite this paper: Hnin Yu Lwin | U Hla Myo Htay "Study and Analysis of Insulator used in Substation" Publishedin International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456- 6470, Volume-3 | Issue-5, August 2019,pp.1160-1163, https://doi.org/10.31142/ijtsrd26578 Copyright © 2019 by author(s) and International Journal ofTrendinScientific Research and Development Journal. This is an Open Access article distributed under the terms of the CreativeCommonsAttributionLicense (CC BY 4.0) (http://creativecommons.org/licenses/by /4.0) ABSTRACT The main purpose of this paper was that to compare design of post insulators and their performance of different post insulator the relative performance of different insulator materials used in substation as lightning arrester, current transformer and potential transformer.Insulatorsareusedtoprotectfromthe dangerous effects of electricity flowing through conductors. This paper presents the role of post insulators are key components of most electrical substation equipment and their features and ability are changing due to the difference type of electrical power incoming line and pollution level of their rating. The peak voltage rating of each arrester at 132 kV is118.6kV,creepage distance is 2904 mm and maximum continuous operating voltage is 94.88 kV. The creepage distanceofcurrenttransformerandpotential transformerat132 kV are 4065 mm. Therefore, in this paper, the effects of material changes, rating changes, pollution level changes of lightning arrester, current transformer and potential transformer in substation are described. Then, analysis and discussion of lightning arrester and instrument transformer are described in this paper. KEYWORDS: lightning arrester, current transformer, potential transformer, substation 1. INTRODUCTION Power system includes three parts such as generation, transmission and distribution. An electrical distribution system is all of that part of an electricpowersystembetween bulk power source or sources and the consumer's service switches. All types of electric utility customers such as residential, commercial, institutional and industrial are heavily dependent on the availability of electric power. Distribution substation is a combination of switching, controlling and voltage step down equipment arranged to reduce sub-transmission voltage to primary distribution voltage for residential, farm, commercial and industrial loads. Electricity distribution is the final stageinthedelivery of electricity to end users. Electrical power systems utilize several voltage levels using power transformers to transfer voltages and connect parts of the power system with different voltage levels. Electric power distribution systems have many unique aspects and requirements. Distribution system can be divided into six parts, namely, sub-transmission circuits, distribution substation, distribution or primary feeders, distribution transformer, secondary circuits or secondary feeders and consumer’s service connections and meter. The distribution plant occupies and important place in any electric power system. Briefly, it function is to take electric from the bulk power source or sources and distribute or deliver it to the consumer’s. The effectiveness with a distribution system fulfills this function is measured in terms of voltage regulation, service continuity flexibility, efficiency and cost. These are completely depends upon sub-station design. The sub-transmission circuits extend from the bulk power sources to the various distribution sub-stations located in the local area. They may be radial circuits connected to a bulk power source at only one end or load and ring circuits connected to one or more bulk power sources at both ends. The sub-transmission over head open wire conductions carried on poles, or some combination of them. The sub- transmission voltage is usually between 11 kV and 33 kV. The distribution substation mustbe required measuring and protected system to prevent equipmentandcircuits,hazards to the public and utility personal, and to maintain a high level of service by preventing power interruption. An electrical insulator is a material whose internal electric charges do not flow freely, and which therefore does not conduct an electric current, under theinfluenceofanelectric field. Insulators are used in electrical equipment to support and separate electrical conductors without allowingcurrent through themselves. Insulators are the integral part of the power system. Among them polymeric insulators are essential for the better performance. Therearemanyshapes and types of insulators used in power system transmission with different densities, tensile strengths and performing properties with the aim to withstand the worst conditions such as surge during lightning and switching operations which will voltage to spike. Reliability of the insulator is the most important property that must take into consideration whether it is a polymeric (composite) insulator or ceramic insulator. The goodinsulator shouldofferoptimumelectrical and mechanical strengths. 2. LITERATURE REVIEW The transition from transmission to distribution happens in a power substation, which has the following functions: IJTSRD26574
- 2. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD26574 | Volume – 3 | Issue – 5 | July - August 2019 Page 1161 1. Circuit breakers and switches enable the substation to be disconnectedfromthetransmissiongridorfordistribution lines to be disconnected. 2. Transformers step down transmission voltages, 35 kV or more, down to primary distribution voltages. These are medium voltage circuits, usually 600-35,000 V. 3. From the transformer, power goes to the bus-bar that can split the distribution power off in multiple directions. The busdistributespowertodistributionlines,whichfanoutto customers. Urban distribution is mainly underground, sometimes in commonutilityducts.Ruraldistributionismostlyaboveground with utility poles, and suburban distribution is a mix. Closer to the customer, a distribution transformer steps the primary distribution power down to a low-voltage secondary circuit, usually240voltsintheMyanmarforresidentialcustomers.The power comes to the customer via a service drop and an electricity meter. Themaincomponentsofelectrical distributionsubstationare: 1. Lightning Arrester 2. Capacitive Voltage Transformer 3. Disconnecting Switch With Earth 4. Gas Circuit Breaker 5. Disconnecting Switch 6. Current Transformer 7. Potential Transformer 8. Power Transformer 3. Sizing of Lightning Arrester Rating Choose of Surge Arresters are required by two paths as followings, 1. Electrical characteristics and 2. Mechanical characteristics. Choose of electrical characteristics and mechanical characteristics are calculated as step by step as following figure. Performance of Choosing Arrester 4. RESULT DATA OF LIGHTNING ARRESTER, CURRENT TRANSFORMER AND POTENTIAL TRANSFORMER Table 4.1 IEC Standard of Lightning Arrester NO. DESCRIPTION TECHNICAL PARAMETERS TYPE OF ARRESTER STATION CLASS HEAVY DUTY GAPLESS a Nominal system voltage (kV) 400 220 132 33 b Highest system voltage (kV) 420 245 145 36 c BIL of transformers (kVp) 1300 900 550 170 d System fault level (kA) for 3 sec. 50 for 1 sec. 40 for 3 sec. 31.5 for 3 sec. 25 for 3 sec. e Lightning Impulse withstand voltage for arrester housing (kVp) 1425 1050 650 170 f Rated Voltage (kV) 360 or as specified in the schedule 198 120 42 g Maxm. Continuous operating voltage (kVrms) 306 168 102 36 h Nominal DischargeCurrent(kAp)of8/20microsecondwave 10//20 10 10 10 i Line discharge class 3 3 3 2 j Minimum Energy Discharge capability (kJ/kV) at rated voltage 10 7.5 7.5 5 k Temporary over voltage withstand capability (kVrms) for 10.0 secs 360 or as specified in the schedule 198 120 42 l Insulation Housing withstand voltages i) Lightning Impulse (Dry) ii) Power frequency (wet) for 10 kA for 5 kA As per IEC 60099-4 m Minimum Creepage Distance (mm) 10500 6125 3625 900 n Pressure Relief Class A o (Minimum) High Current Impulse withstand (4/10 micro second wave) kA (peak) 100 100 100 100
- 3. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD26574 | Volume – 3 | Issue – 5 | July - August 2019 Page 1162 p Maxm. Lightning Impulse (8/20 micro-second Wave) residual voltage (kVp) 5 kA 10 kA 800 850 517 550 320 340 112 120 q Maxm. switching surge (30/60 micro-second wave) protective level (kVp) 500 Amps 1000 Amps 2000 Amps - - 750 - 455 - - 280 - 98 - - r Maxm. Steep Impulse (1/20 MS impulse) residual voltage at 10 kA (kVp) 1050 600 372 130 s Partial Discharge (pico-coulomb) when energized at 1.05 times its continuous operating voltage Not exceeding 10 PC t Rated Frequency (Hz) 50 u Minm. visible corona discharge voltage (kVrms) 320 - - - v Min. Bending load (kgm) 1000 1000 500 500 w 1 min. p.f. withstand (kVrms) voltage(dry&wet)forarrestor housing 630 460 275 70 x Switching Impulse withstand voltage (250/2500 micro second) dry & wet for arrestor housing (kVp) ± 1050 - - - y Pressure relief Current i) High Current (kA rms) 40 40 40 40 ii) Low Current (kA rms) As per IEC Table 4.2 Analysis of Calculation Results for Post Insulator in LA System Voltage (kV) 132 33 Nominal Creepage Distance (mm) 2904 726 Shed Number Big 30, small 29 Big 9, small 8 Table 4.3 IEC Standard of Post Insulator (110 kV - 145 kV) for CT and PT Catalog No 2814 2819 2820 2821 2831 Rated Voltage (kV) 110 110 110 110 110 Nominal Creepage Distance (mm) 2650 3150 3150 3200 2016 Mechanical Load (min) Bending (kN) 16 6 10 20 Mechanic-al Load (min.) Torsion (kN.m) 6.0 3.0 4.0 6.0 Withstand Voltage (kV) Lightning Impulse 450 450 450 450 Withstand Voltage (kV) Power Frequency Dry 245 245 245 Power Frequency Wet 185 185 185 Shed Number 23 big 12 small 12 big 12 small 12 big 12 small 12 16 Weight (kg) 93 77 87 102 50 Table 4.4 IEC Standard of Post Insulator (20 kV - 35 kV) for CT and PT Catalog No 2229 2200 2204 2206 2209 2213 Rated Voltage (kV) 20 35 35 35 35 35 Nominal Creepage Distance (mm) 400 648 625 648 650 1260 Mechanical Load (min) Bending (kN) 20 6 8 4 4 4 Torsion (kN.m) - 3.0 2.0 1.2 1.2 1.8 Withstand Voltage (kV) Lightning Impulse 150 185 185 185 200 250 Power Frequ-ency Dry 75 100 100 100 110 135 Wet 50 80 80 80 70 95 Shed Number 4 7 6 7 7 big 5 small 4 Weight (kg) 31 17 16 12 15 27 5. CONCLUSIONS Electrical power distribution is the final stageinthedelivery of electric power, it carries electricity from the transmission system to individual consumers. Insulators are the integral part of the power system. The insulators aresubjectedtothe environmental stresses such as humidity, temperature and pollution. Therefore, it has dual functions as electrical and mechanical function in power system networks. Insulators are made from dielectric materials such as ceramic andnon- ceramic insulating materials.Lightningarresterismadewith non-ceramic insulating materials and current transformer and potential transformer are made with ceramic insulating material.
- 4. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD26574 | Volume – 3 | Issue – 5 | July - August 2019 Page 1163 Lightning arrester and instrumenttransformers(CTandPT) are equipped at the incoming line and outgoing line of substation. Without equipping the instrumenttransformers, the substation may be damaged because of overcurrent and overvoltage. So, it is important to have right current and voltage rating of CT and PT for different lines. Numbers of shed, minimum creepage distance, dry arcing distance and diameter are differ according to its rating. In this paper, the efficiency and design of LA, the peak voltage rating of each arrester at 132 kV is 118.6 kV, creepage distance is 2904 mm and maximum continuous operating voltage is 94.88 kV. The creepage distance of current transformer and potential transformer at 132 kV are 4065 mm. 6. ACKNOWLEDGEMENTS The author deeply wants to express special appreciation and heart-left thanks to Dr. Yadana Aung, Professor and Head the Department of Electrical Power Engineering, Technological University (Mandalay) for her willingness to share her ideas and helpful suggestions on this paper writing. 7. REFERENCES [1] [15 Tun] Tun Naing, "Potential Transformer and Surge Arrester", 2015. [2] [14 Ano] IEC, "Potential Post Insulators", 2014. [3] [14 Lig] Ligong Gan, P-Eng Transmission Engineering (AESO), "Insulation coordination in the Alberta Interconnected Electric System", 2014. [4] [13 Koo] Koos Holtzhyousen and Dr WL Vosloo, "High Voltage Engineering Practice and Theory",2013. [5] [12 Ano] Anony mous, "3Fl Silicons long Rod Insulators for Transmission Lines 69-500 kv", 2012. [6] [12 Ank] AnkaRa Seramik, "Outdoor Solid Core Post Insulator", 2012. [7] [00 Zae] Zaengl, W.S and E-kuttel, "High Voltage Engineering Fundamentals", 2nd [Ed] J.kuttel (2000). [8] [95 Fun] Funchiron, "Overvoltages and insulation coordination in MV and HV", 1995. [9] [93 IEC] IEC, "Station Post Insulators", 1993. [10] [92 IEC] IEC, "CompositeInsulatorsforACOverhead Lines With Nominal Voltages Larger Thon 1000 V - Annexure C", 1992. [11] [88 Loo] Looms, J.S.T, "Insulators for HighVoltages", Peter Peregriness, London, 1988. [12] [86 IEC] IEC, "Guide for the SelectionofInsulatorsin Respect of PollutedConditions",IECRecommendations Publication 815, 1986.