1. Eskom Distribution ERTC `09
Durban, South Africa, 18th November 2009
Bare Jumpers-
lead to bird
electrocutions
Replacement of LDPE pipe using PVC Covered Jumper Conductor
S. Nayager C. Shunmugam
Engineer in Training - T&Q Department Technical Engineering Investigator, T&Q Department
Phone: 072 6231205, Email: nayages@eskom.co.za Phone: 031 710 5416, Email: shunmuc@eskom.co.za
Abstract – On MV overhead networks, bare aluminium jumpers
are used to connect auxiliary equipment such as transformers,
voltage regulators and reclosers to the system. Due to the number
of bird/wildlife deaths caused by these bare jumpers, the
Endangered Wildlife Trust (EWT) required that Eskom structures,
especially the equipment structures, be bird/wildlife friendly. One
of the ways this was achieved was to use an insulated covering
over the bare jumper to mitigate the problem and reduce the
number of wildlife fatalities. The low density polyethylene (LDPE)
pipe was chosen as the best solution to cover the bare jumpers
thereby making the equipment structures, “environmentally
friendly”.
Although the LDPE Pipe was an excellent environmental solution,
it has created three engineering problems which will be discussed
further in this paper. These engineering problems have affected
our networks performance creating a poor quality of supply to
Eskom customers. Due to this our SAIDI and SAIFI targets were
being negatively impacted. To improve our plant reliability an
alternative to the LDPE pipe had to be researched. This paper
explains the newly designed Polyvinyl Chloride (PVC) covered
jumper which was piloted on two feeder networks namely
Esikhawini NB 17 (North Coast Empangeni) and Marina Beach
NB 78 (South Coast). The results of the pilot study are discussed
and recommendations are made on the proposed way forward.
I. INTRODUCTION
In habitats where natural nest substrates are limited, power
line structures have become a common nesting site for many
birds such as vultures and raptors. Likewise other birds also
use these power lines and poles for perching, roosting and
hunting. Due to this, bird electrocutions on power lines has
become a concerning issue for both Eskom and wild-life
groups. The biological and environmental components that
influence electrocution risk include the following:
Body size
This is the one of the main causes for bird fatalities on both
sub transmission and reticulation lines. Birds with large wing
spans come into contact with the energized conductors when
either flying in or taking off from power line structures and
auxiliary equipment such as transformers.
Figure [1]
The picture above shows an example of a vulture sitting at
the top of a pole structure. It can be seen that this bird has a
large wing span which causes a short circuit on the power
system and thus making it susceptible to electrocutions.
Habitat
In open areas lacking natural perches, power utility poles and
auxiliary equipment provide sites for hunting, resting,
feeding, roosting or nesting. A habitat with an abundance of
prey will attract a variety of birds.
Cable/Jumper Configurations
Configurations with closely spaced energized phase
conductors and grounded wires as shown below are being
readily bridged by birds. The arrow shows potential danger
for birds: on the auxiliary transformer the jumpers coming off
from the main line are in close proximity from one another.
Figure [2]

2. In 2007/2008 a total of 18 bird electrocutions had occurred
with about 89% of the deaths taking place on reticulation
lines.
Bird Electrocutions 2007/2008 Eastern Region
0
2
4
6
8
10
12
14
16
18
Reticulation Sub transmission
Power Lines
Numberofelectrocutions
Figure [3]
II. ENDANGERED WILDLIFE TRUST(EWT)
ENVIRONMENTAL REQUIREMENTS
In 2002 the Endangered Wildlife Trust (EWT) required that
Eskom make all their jumpers terminating on auxiliary “bird
friendly” due to the high fatality rate. According to standard
DST 34-1191 titled ‘General Information and Requirements
for Overhead lines up to 33kV’ the details for a covered
jumper was specified. The conductor’s jumper insulation is
defined below:
“Jumpers for auxiliary structures and line equipment shall be
made from conductor that is covered with a suitable
insulating material to minimize the risk of birds being
electrocuted. Terminations shall be shrouded in particularly
sensitive areas and if insulating jumper material is bared for
the purpose of applying earths, these bared areas shall be
staggered vertically to ensure that simultaneous contact of
two bared sections by a bird is not possible.”
From this specification the low density polyethylene (LDPE)
pipe was chosen as the most cost effective method to provide
the insulating covering on all jumpers to auxiliary equipment.
This will reduce the number of bird electrocutions as well as
provide the jumper with protection from the natural elements.
However over the past few years the LDPE pipe has become
problematic causing more damage to jumper conductors than
protection. The problems with LDPE involve:
Increased fatigue failure- In windy areas LDPE pipe
chaffs into jumper conductor and over time the
conductor breaks off
Water accumulation in LDPE pipe could lead to
accelerated degradation of the aluminium conductor.
Fault finding has become more difficult for TSC
operators since the jumper conductors are enclosed in the
LDPE pipe hence compromising visibility.
A sample of a damaged jumper containing the LDPE pipe
was obtained from Marina Beach (NB78). From analysis it
can be seen that strands of the jumper has been damaged
before the crimp fitting canceling any uncertainty of incorrect
crimping.
Figure [4a]
Figure [4b]
III. STATISTICS
Jumper failures have impacted largely on customer delivery
and System Average Interruption Duration Index (SAIDI),
System Average Interruption Frequency Index (SAIFI)
values. As it can be seen below, a total of 947 jumper failures
in general had occurred in the year 2008 for the Eastern
Region. The latter half of the graph shows a high failure rate
due to high winds and summer rains.
Figure [5]
0
20
40
60
80
100
120
140
160
Number of failures
January April July October
Month
Jumper Failures-2008
Series1

3. In terms of jumper failures, Marina Beach NB 78 and
Esikhawini NB 17 were rated as two of the worst performing
networks in the Eastern Region. At the Technology Forum
Change Control (TFCC), a decision was taken to pilot a PVC
covered ACSR aluminium conductor. This was done on
Marina Beach NB 78 on August 2008 and on Esikhawini NB
17 on July 2007. The graph below shows the qualitative
comparison of the jumper performance on Marina Beach NB
78. The number of jumper failures is inclusive of the LDPE
pipe damaged jumpers.
0
1
2
3
4
5
6
7
8
Number of
failures
2004 2005 2006 2007 2008 2009
Year
Marina Beach NB 78
Figure [6]
Taking a look at the figures from the chart it can be seen that
from 2008 to 2009 there has been a reduced failure rate. From
the end of August 2008 (when PVC covered jumper was
installed) to the current period jumper failures had dropped
substantially. Marina’s Beach Technical Service Officer has
confirmed that there has been no PVC covered jumper
failures to date. The energy charges (cents per kW/hr) over
the last six years were obtained from the pricing and tariff
department for home power users. A calculation for the loss
of revenue was determined using the following tariff costs
per year and an assumption of a unity power factor: 2004
(27.95c kW/hr); 2005 (30.16c kW/hr); 2006 (31.70 c kW/hr);
2007 (33.57 c kW/hr); 2008 (45.05 c kW/hr); 2009 (57.46 c
kW/hr). The total loss in revenue over the past 5 years was
R114382.10 due to jumper failures. This does not cover
repair team labour and transport costs.
0
5000
10000
15000
20000
25000
30000
Rands
2004 2005 2006 2007 2008 2009
Year
Marina Beach NB78 : Loss of Revenue
Figure [7]
Looking at Esikhawini NB17 it can be seen that 2007
contained the highest amount of jumper failures. After the
installation of the PVC jumpers it was noticed that there was
a significant drop in failures which has improved Eskom’s
SAIFI and SAIDI values.
0
1
2
3
4
5
Number of jumper
failures
2004 2005 2006 2007 2008 2009
Year
Esikhawini NB 17
Figure [8]
Using the same tariff prices from the previous page the
following figures were calculated showing the loss of revenue
for Esikhawini Network breaker 17 over the past 5 years. The
total loss is R 36842.13 with the lowest loss being in 2009
which shows that there has been an improvement on this
network with the use of the covered jumpers
0
5000
10000
15000
20000
25000
Rand
2004 2005 2006 2007 2008 2009
Year
Esikhawini NB17-Loss of Revenue
Figure [9]
IV. TESTING AT VIBRATION RESEARCH TEST
CENTRE-UKZN
In order to determine if the LDPE pipe was the root cause of
jumpers failing, an overhead to auxiliary transformer
simulation was setup at the University of Kwa- Zulu Natal’s
Vibration Research Test Centre (VRTC). For the test an
Electrodynamic Vibration Tester (shaker) was used to imitate
the vibration created by wind on the LDPE pipe. Fox
conductor was chosen for the test since it’s the most widely
used on reticulation lines for jumpers. The top half of the Fox
conductor was connected to an attachment beam in the
ceiling using a preform dead end and the bottom half was

4. 1
x: 8, y: 0.0956147
x: 49.0383, y: 0.102629 Locked
8 10 20 50 60
0.05
0.1
0.2
m/s(Log)
Hz(Log)
A Sine m/s [Control] B Sine m/s [CH 2]
1 x: 49.0383
y: 0.102629
L D P E
P ip e
S h a k e r
H e a d
S h a k e r
terminated in the shaker head. To obtain an accurate
simulation, a LDPE pipe of larger diameter than the
conductor was fitted over the conductor. The final setup is
shown in the picture below:
Figure [10]
Two sensors were used in the experiment; the sensor below
the shaker head measures the excitation frequency generated
and the sensor on the LDPE pipe measures the amount of
vibration that the pipe experiences.
Figure [11]
A sweep test was carried out using the PUMA control system
which is responsible for determining the highest resonant
frequency acting on the LDPE pipe. The range was chosen
between 8Hz and 60Hz to determine the highest points of
vibration, ideally to 50Hz to match normal load conditions.
To provide an extra force to simulate vibration created by
wind an amplitude distortion of 6mm from the conductor and
LDPE was maintained. When the excitation frequency
matched the natural frequency of the pipe, the maximum
vibration was obtained. The test was run over 3 days, with the
first day running at 11Hz and the remaining days at 49Hz
with both set at 9.9G to simulate wind. These frequencies
were chosen from the sweep test graph shown below:
Figure [12]
The test had run for 20 hours over a 3 day period after which
the jumper was examined under a microscope at Pfisterer.
The images below showed that the LDPE pipe had chaffed
the conductor which could eventually lead to jumper failure.
Figure [13a]

5. Figure [13a]
V. RESEARCH AND DEVELOPMENT
At the Technology Forum Change Control (TFCC) a decision
was taken to pilot an alternative to the LDPE pipe. A pilot
PVC covered jumper project was run in 2007 in two areas,
Esikhawini NB 17 (July 2007 installed) and Marina Beach
NB 78 (August 2008 installed). These network breakers were
chosen as they were the worst performing networks in the
eastern region in terms of jumper failures. The PVC cover
jumper (manufactured by Aberdare) was designed to use a
Fox conductor (ASCR) and was to be greased according to
CASE 3 ie “All the conductor is greased including the outer
layer”. In 2009 IARC Power Plant Technology Department
requested that the installed samples from the inland and
coastal areas be removed and tested to determine the
following:
To establish the effectiveness of the water blocking
of the cover
To determine the flammability of the cover material
if exposed to an open flame
To determine what temporary insulation the material
can provide
The test results showed:
The greased PVC covered jumper when analysed showed no
indication of water ingress or dirt. When the cover material
was placed under an open flame, it immediately reacted to the
heat by changing texture and colour. However, the material
did not continue to burn once the flame was removed. When
the sample was exposed for more than 5 minutes to the flame,
the damage was limited to the area that was within the flame.
Withstand and flashover tests for the PVC covered jumper
were conducted at Simmerpan’s HV lab. The test voltage was
gradually increased up to 36 kV and maintained for 60
seconds; thereafter it was increased gradually until flashover,
i.e. puncturing of the PVC cover occurred. All samples had
an insulation thickness of 1.6mm and eventually flashed over
above 50kV. After drawing up a final specification for the
PVC covered jumper, Aberdare had informed Eskom that
they had a problem manufacturing the jumper according to
CASE 3 greasing. The greased outer strands made the
extrusion process difficult as the PVC covering did not
adhere to the greased conductor. The only solution was to
grease the conductor according to Case 4: The inner
interstices will be completely filled with grease and the outer
interstices will be fully extruded by the PVC covering.
VI. CONCLUSION
Performance of the piloted PVC covered jumpers on feeder
network Marina Beach 78 and Esikhawini Network Breaker
17 has without a doubt proved to be the most cost effective
alternative to the LDPE pipe. The Technology Forum Change
Control has had positive feed back from Field Services
personnel. Accordingly the Regional Engineering
Management has authorized the use of PVC covered jumpers
on all auxiliary equipments for medium voltage overhead
lines. Using this PVC covered jumper as an alternative would
definitely eliminate the engineering challenges that was
experienced with the LDPE pipe. Standardisation of PVC
covered jumpers on MV networks would make a positive
impact on network performance and plant reliability. Hence
our quality of supply to Eskom’s customers would be
siginificantly improved.
ACKNOWLEDGMENT
1]. D.R. Rossouw Theron- IARC Chief Engineer,Power Plant
Technology
2]. Jacques Calitz- IARC Material Specialist
3]. Vibration Research Test Centre (VRTC) –Pravesh
Moodley
4]. Megan Diamond(Endangered Wild Life Trust(EWT)
5]. Cyril Shunmugam-Technical Engineering Investigator
(TEI)
6]. MV Standard-DST 34- 1191- “General Information and
Requirements for Overhead lines up to 33kV”
7]. IEEE-Transaction on Power Delivery, VOL 19 No 4,
October 2004, R Sundarajaran et.al and others-
“Preventive Measures to Reduce Bird Related Power
Outages- Part 2: Streamers and Contamination”
8]. Nivan Pramjeeth- Technical Service Officer- Marina
Beach
9]. Brett Goosen- Works Co-ordinator Empangeni Technical
Centre
10]. Kevin Bower-Data Analyst-Plant Department
11]. Pfisterer- Brian Murry- Mechanical Engineer