Lightning Protection for Medium Voltage Overhead Distribution Lines in High Lightning Density Area Prof.Dr. Reynaldo Zoro. Dr. Syarif Hidayat, Tulus Leo Lightning Research Center School of Electrical Engineering and Informatics Institute Technologi Bandung (ITB), Indonesia zoro@hv.ee.itb.ac.id ; tulus.leo@gmail.com

Content Lightning in Tropics Lightning Protection for MV Lines Introduction Lightning in Tropics Lightning Protection for MV Lines Reseach Area Research Results Conclusion

Introduction The goal of this research is to minimize the disturbance on MV line in the area with high lightning density in Serpong area Over the years several tripping and conductor damages occur due to lightning strikes. Several solutions have been evaluated over the years which can improve line performance against lightning strikes such as installation of overhead ground wire and the relocation of lightning arrester.

Indonesia; Maritime Continent St. Petersburg, Rusia Equator Line

Java Island & Bali West Java Bali Island

GFD for Java Island Recorded from JADPEN

Reseach Area ; Serpong Lightning Measurement Station Mnt. Tangkuban Perahu +2023 m SERPONG

GFD for West Java Jakarta serpong Lightning Measurement Station Mnt Tangkuban Perahu GFD for West Java West Java Lightning Flash Density (Ng)

SERPONG AREA

GFD for Serpong Area on 20 x 20 km2 window Ng is around = 15-40 strike/km2/yr

Monthly Variant of Lightning Activity in Serpong Area

Protection of MV Overhead line Protection of MVOH lines Shielding Wire Metal Oxide Arrester Multi-Chamber System

Protection of 20 kV Lines in Indonesia by using; MOA arrester and Overhead Ground Wire 1 OHGW reduce induction up to 33%. 2 OHGW reduce the induction up to 66% (Peek).

Multi Chamber System (MCS) The base of multi chamber arresters (MCA), shown in next picture. It comprises a large number of electrodes mounted in a length of silicon rubber. Holes drilled between the electrodes and going through the length act as miniature gas discharge chambers.

Fig. 1. Multichamber system (MCS): (a) Diagram showing the discharge onset instant. (b) Diagram showing the discharge end instant. 1) silicon rubber length, 2) electrodes, 3) arc quenching chamber, and 4) discharge channel.

Multi Chamber System (MCS) When a lightning overvoltage impulse is applied to the arrester, it breaks down gaps between electrodes. Discharges between electrodes occur inside chambers of a very small volume; the resulting high pressure drives spark discharge channels between electrodes to the surface of the insulating body and, hence, outside into the air around the arrester.

Fig 2. Spark discharge occurs into the air around the Multi chamber arresters installation 20-kV lines.

Serpong lines characteristics A 20 kV feeder, called “Ruko” in Serpong region has been chosen to be equipped with the multi-chamber arresters. The choice is determined due to highest lightning outage of the feeder. Outages have been recorded through this logger at substation and reclosers as shown on table 1. It can be noted that in total of 40 to 60 outages took place every year on these lines. Average outages recorded per 100km per year at feeder KDS4 and feeder SR20 is 120 outages.

Table 1. Trips records on switchgear from substation and reclosers of feeders. Table 2. Data of the research location which are equipped by arrester on SR20 and KDS4 feeders.

Fig 3. 20kV lines of feeder SR20 and feeder KDS4 Fig 3. 20kV lines of feeder SR20 and feeder KDS4.Orange Color is the vicinity area, and in blue color is the whole research area.

Installation of Arresters On 20 October and 19 November 2013, a total of 44 arresters have been installed in the vicinity area. Installed arrester was shown in Fig 4, one arrester per pole is installed on alternate phases. This arrester has been installed on poles that were not equipped with gapped or gapless metal oxide arresters (MOA). Arrester was simply mounted on the cross arm using standard metal fitting.

Fig 4. Multi-Chamber Arresters installed on alternate phases, one piece per pole

Research Result Before Installation of MCA After Installation of MCA

Before Installation of MCA Nowadays Lightning data for this research derived from BMKG, (Badan Meteorologi, Klimatologi Dan Geofisika) or Indonesia Weather Service Office. From Feb 2012 to Oct 2013, 601 days, 90 trips were observed on KDS4 and SR20 feeder on more than 55 days. Lightning activity over the related days were collected and analyzed. It can be seen that only from 55 days of lightning, lightning activity in vicinity of the substation can reach 17,07 ground flashes per square kilometer per year.

Table 5. Lightning occurrence at time of recloser’s trips. Table 4. Lightning activity during 54 days from 27 Feb 2012 to 20 Oct 2013 Table 5. Lightning occurrence at time of recloser’s trips.

After Installation of Arresters According to BMKG, (Weather Station Office of Indonesia) data during the period of installation there is ground flash density was around 15 ground flashes per square kilometer per year. On the overall area, only 7 occurrences were observed after installation of Multi-Chambers Arresters. Number of occurrence of lightning and trips per 100km of circuit per year decreased from 29 before installation to 12 after installation of the Arresters, preventing more than 50% of outages.

Table 6. Lightning occurrence at time and day of distribution lines trips

Operability of Multi-chamber arrester on 20kV Networks More than 354 days after installation no increase nor excessive outages number were observed. Table 3 shows a reducing of trips per 100km of lines. Table 3. Trips records before and after installation of Multi-Chambers Arresters

Conclusion During the period of installation of MCA (2013 – 2014) the ground flash density was around 15 ground flashes per square kilometer per year compared to 17.07 GFD before (2012 -2013). Multi-Chambers Arresters operated 11 times and had a positive effect on the protection of the 20 kV overhead line by reducing number of trips.

Research results shows that MCA contributed to improve line performance by 50% against lightning strikes. During this research period and distribution line did not suffer from any nuisance tripping.

Thank You….