Characteristics for Polycomposite Brackets for Direct Electric Supply

of Railways

Mihail Arzannikov

, Aleksei Kosakov

, Yuri Kochunov

1,2 b

and Aleksandr Suhoguzov

Research and Production Enterprise «Elektromash», Ekaterinburg, Russia

Ural State University of Railway Transport, Ekaterinburg, Russia

Keywords: Direct lightning strike, surge voltage, discharge, protective device, polymer composite material, bracket.

Abstract: To evaluate the discharge characteristics of polymer composite brackets of 6-10 kV overhead lines, the

possibility and necessity of protecting such structures from lightning overvoltage. Methods: Experimental

studies are presented in the laboratory of high voltage engineering of the Ural State University of Railways,

using a pulse voltage generator. Results: The results of the work are conclusions on increasing the reliability

of operation of polymer composite brackets of power transmission lines. Practical significance: The results

of the work can be used in the development of an overhead line protection system against direct lightning

strikes and pulse overvoltages and as theoretical material for students of higher educational institutions.

1 INTRODUCTION

Overhead lines (OL) of 6-10 kV are of great length in

the Russian power grid complex. In recent years,

special attention has been paid to overhead line

protection against impulse over voltages (IO) and

direct lightning strikes (DLS), the consequences of

which may lead to irreparable breakdown or

overlapping of insulation, damage to the sheath of

self-supporting insulated wires (SSIW) and,

consequently, to power outages for consumers and

additional costs of rehabilitation work.

Overvoltage protection is based on several

principles:

1. Limiting the number of modes in which

dangerous overvoltage can occur by means of

schematic measures;

2. Limiting the amplitudes of steady-state over

voltages, resulting in a reduction of transient

overvoltage;

3. Limitation by means of hardware.

Hardware means a device that is installed near the

equipment to be protected and that shunts the

protected object when an overvoltage occurs.

Overvoltage arresters, surge suppressors and hybrid

circuits can be used as such devices.

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The operating principle of the protective device is

that it prevents dangerous over voltages from arising

on the electrical system and does not prevent the

electrical system from functioning at operating

voltage.

2 MATERIALS AND METHODS

A literature review has shown that this problem is

topical all over the world (Kissling, et al., 2018;

Luk’yanov and Luk’yanova, 2020; Zielenkiewicz, et

al., 2018; Long, et al., 2016; Dev Paul, 2005; Ono, et

al., 2017; Nai, et al., 2019; Ono, et al., 2018; Arai, et

al., 2018). In order to prevent the occurrence of over

voltages on the protected object and its damage, the

volt-second characteristic of the protective device

(curve 1) should lie below the volt-second

characteristic of the protected object (curve 2)

(Figure 1). If this requirement is met, dangerous

overvoltage cannot occur, because in the case of a

voltage surge (curve 3), a breakdown of the protective

device occurs, with a voltage drop at point A. If the

protective device is missing, a breakdown of the

object insulation at point B occurs. Following the

100

Arzannikov, M., Kosakov, A., Kochunov, Y. and Suhoguzov, A.

Characteristics for Polycomposite Brackets for Direct Electric Supply of Railways.

DOI: 10.5220/0011579700003527

In Proceedings of the 1st International Scientiﬁc and Practical Conference on Transport: Logistics, Construction, Maintenance, Management (TLC2M 2022), pages 100-107

ISBN: 978-989-758-606-4

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

surge current, a residual current flow through the

protective device, and a residual voltage U

res

appears

on the protective device. When operating the

protective device, the accompanying current must be

extinguished at the first zero crossing, otherwise the

protective device may trip the installation.

Accordingly, the following requirements can be

formulated for the protective device: the volt-second

characteristic of the protective device must be lower

than that of the object to be protected; the protective

device must have a certain guaranteed electrical

strength; the residual voltage on the protective device,

which characterizes its limiting capacity, must not

exceed values that are dangerous to the insulation of

the equipment; the follow-up current must be

disconnected in a time lower than the tripping time of

the protection; the protective device must allow for a

certain number of trips without inspection and repair,

and be safe for the surrounding equipment. The

protective apparatus must be able to operate without

inspection and repair and must be safe for the

surrounding equipment.

As already mentioned, one of the types of

overvoltage protection is the use of surge arresters on

overhead lines: tubular, valve, long-spark and

multicamera. In the literature (Podporkin, 2020;

Napolitano, et al., 2019; Podporkin, et al., 2019;

Ivanov, et al., 2018) the principles of arrester

operation, methods of their fixing, methods of

protection are presented in details. It is only worth

noting that in any case there is a breakdown of the

spark gap between the current-carrying part and the

grounded part of the protected object.

Figure 1: Operating principle of the protective device: 1 -

characteristic of the protective apparatus, 2 - characteristic

of the protected object, 3 - surge wave, 4 - sheared surge

wave.

On overhead power transmission lines of direct

current supply of railway transport, the surge arrester

installation is carried out on the traverse by turns, on

the same principle as power transmission lines

6-10 kV of the electric network complex of

"ROSSETI" (figure 2) (Podporkin, 2020; Napolitano,

et al., 2019; Podporkin, et al., 2019; Ivanov, et al.,

2018).

However, it should be noted that overhead

6-10 kV lines supplying signalling, centralization,

interlocking of railway (signalling and interlocking)

devices and longitudinal power supply lines for non-

Figure 2: Diagram of installation of long-spark arresters RDIP on 6-10 kV overhead lines: http://streamer.ru.

Characteristics for Polycomposite Brackets for Direct Electric Supply of Railways

101

traffic consumers (LP) can be placed on overhead

system poles on brackets.

Today brackets are made of metal, wood and

polymer composite materials (PCM). Moreover,

wooden brackets and PCM brackets are dielectric and

do not have a grounded part across the surface to

which an arrester can be connected. This has raised

the question of the protection of 6-10 kV overhead

lines using insulating support structures.

The overhead line brackets and PE brackets are

attached to a common ground electrode on the

overhead line pole, i.e., all devices are grounded to

the same point. We will consider the case of a metal

bracket with insulators for a group grounding cable

(figure 3). In this case, alternating between the phases

of the arrester is not effective, and there are several

factors to account for:

1. A direct lightning strike (DLS) on the overhead

system. A direct lightning strike (DLS) may overlap

the insulation of the catenary and transfer the

discharge onto the bracket. Since the arrester is on a

far side phase, an inter-phase short-circuit can be

formed on phases A and B;

2. The flow of the discharge through the

grounding cable will be similar to the DLS to the

overhead line;

3. DLS in phase C, when the arrester is installed

in phase A, can cause a MF short circuit in phase C

and B;

4. DLS in phase A or C can cause an insulation

breakdown, but no MF is likely to occur because an

arrester is installed in phase B.

This is confirmed by the application of the surge

arrester (SA) shown in Figure 4, which operating

principle is based on generating MF short circuits and

disconnecting the line, which is undesirable for

signalling devices, while not protecting the insulators

against breakdowns.

3 RESULTS AND DISCUSSION

According to the above mentioned, the installation of

phase-sharing arresters is not effective in protecting

the over voltages of the overhead line because the line

can be disconnected from the MF short-circuit. The

use of arresters on each phase is not cost-effective.

Table 1: Technical characteristics of the MKS system arrester.

Arrester t

e RMKE RM

Voltage class, kV 6

–

Highest permissible continuous operating voltage, kV 7.2

–

Spark gap, m

–

80 40

–

ulse dischar

e volta

e kV, max. 120 100

One-minute AC volta

e, kV, not less:

- in dr

state 40 30

- in the rain 30 20

Magnitude of expected main’s fault current at which at least 10 trips are guaranteed,

kA, max.

3.5 0.6 – 3.0

Impulse current withstand duration to half fall of at least 50 µs, at least 2 exposures,

20 30

Arc extin

uishin

time of trailin

current, ms, max. 10

–

Flow rate, Cl 2.4

–

Weight, kg 3.7 0.9

Table 2: Technical data of the KPSIP-3-p bracket.

Parameter name Norm

Deflection, mm, max. 13

Insulation resistance, min. ohm 1013

Current leakage path length, mm 500

Short-term voltage in dry state, kV 65

Short-term voltage in the rain, kV 45

Withstand voltage in soiled and wetted condition, 50 % voltage, kV 23

Tracking and erosion resistance at 15 kV, h 500

Impulse withstand voltage with a steep front, kV 250

Adhesion of the protective sheath, grade 1

Weight, kg max. 25

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Therefore, the use of one arrester on the central phase

and the use of transposition is the best option for the

overhead line of signalling and overhead lines located

on the pylons of the contact network of railways. In

terms of the use of metal brackets with suspended or

pinned insulators, the principle of mounting the

arrester is described in detail by arrester

manufacturers. One end of the device is fixed to the

rod or shackle of the insulator, on the ground side, the

arrester element is connected to the wire or through

the air gap. Figure 5 shows the arrester with MKS

system (Podporkin, 2020; Napolitano, et al., 2019;

Podporkin, et al., 2019; Ivanov, et al., 2018).

Multicamera arrester are more effective, than

those of RDIP type, because of the high currents and

their application at overhead lines of signalling and

power lines is preferable. Technical characteristics of

these arrester are given in Table 1.

One of the perspective trends in increasing the

reliability of signalling and power overhead

transmission lines is the use of brackets made of

polymer composites. Such brackets are insulation-

supporting structures, which ensure mechanical and

electrical strength of the line. Figure 6 shows an

example of a polymer bracket.

Figure 3: Protection operation when using an arrester on a polymer bracket with a glass insulator in the centre phase.

Figure 4: Polymer bracket KPSIP-3 BOREL with RMKE-20 arrester. a) - version with glass insulator; b) - version with

plastic insulator.

Figure 5: Schematics of the testing process. a) - Voltage supply to rod; b) - Voltage supply to wire.

Characteristics for Polycomposite Brackets for Direct Electric Supply of Railways

103

Figure 6 shows polymeric bracket KPSIP-3-p

BOREL produced by “SPE “ELECTROMASH””

Ltd. (Kochunov and Volgin, 2020), Table 2 shows its

technical parameters.

From the data shown in Table 2 we can see that

discharge parameters of the bracket are quite high

(250 kV), but voltage at lightning discharge can be

much higher. Similarly to the scheme shown in Figure

3, let us consider the operation of overhead lines with

the use of brackets made of PCM (figure 7).

Assuming that a DLS has occurred on a phase far

from the pole, it is difficult to overcome the entire

length of the insulating rod to the grounded part, so

the overvoltage may occur on the adjacent phase and

Figure 6: Schematic diagram of the pulse voltage generator installed in the laboratory of High Voltage Engineering of

the Ural State University of Railway Transport.

Figure 7: Exterior view of the pulse voltage generator, installed in the Laboratory of High Voltage Engineering of Ural

State University of Railway Transport.

Figure 8: Test bench mounted in the Laboratory of High Voltage Engineering of Ural State University of Railway

Transport.

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cause MF short circuit, there will be undesirable

power failure of signalling devices.

Experimental tests were carried out in April 2021

in Laboratory "High Voltage Engineering" (HVE) of

Federal State Budgetary Educational Institution of

Higher Professional Education "Urals State

University of Railway Transport" (USTU) by

applying pulse voltages on a sample bracket with

multi-chamber arrester RMKE-20. Figure 9 shows

diagrams of testing. The L in Figure 9 is shown as the

length of the insulating part of the samples.

The tests were carried out using a four-stage surge

generator (figures 6, 7).

The test voltage was applied to a sample rod of a

polymer composite bracket (figure 8) at different

distances from the wire attachment point (measuring

points). Observation of the discharge process with

discharge voltage measurement was carried out for at

least 50 discharges at each measuring point. The

results of the tests are shown in Table 3.

According to the testing results, it follows:

1) when mounting the arrester on the polymeric

bracket the discharge voltages of the system "arrester

- polymeric bracket" exceed the rated values of the

arrester mounted on the grounded metal bracket by 10

- 40%;

2) the polymer bracket itself does not protect

against over voltages to neighbouring wires - when

lightning strikes the wire, the discharge goes to the

neighbouring wire, the breakdown passes through the

air, and not through the insulating structure body

(bracket);

3) the arrester only works when the grounding is

in place.

Figure 10: Schematic diagram of overhead power line protection with polymer brackets and surge arresters. 1 - support; 2 -

polymer bracket; 3 - polymer insulator; 4 - connecting cable; 5 - metal bracket; 6 – arrester.

Figure 9: Polymeric bracket KPSIP-3 BOREL with insulators. a) - version with glass insulator; b) - version with plastic

insulator.

Characteristics for Polycomposite Brackets for Direct Electric Supply of Railways

105

According to the test results, it was determined

that the use of arrester without its grounded part on a

polymer bracket is not effective, it is necessary to

develop and use other arrester constructions. For

example, in lightning-prone areas and in highly

polluted areas, combined insulation can be applied

(figure 9) with the use of surge arresters (figure 10).

The use of polymeric brackets with arresters on

overhead lines can be similar to the wooden bracket

with tubular arresters (figure 10).

The installation of protective equipment on

overhead lines and overhead lines is in accordance

with Russian national standards and SNiP.

4 CONCLUSIONS

Considering the theory of arrester operation on

6-10 kV overhead lines, it can be stated that

installation of arrester on OL of signalling and power

lines with alternating phases is not efficient enough

due to possible inter-phase short circuits. The use of

polymer brackets on overhead lines increases the

electric strength of the overhead line, especially in

combination with insulators, but does not protect the

overhead line from direct lightning strikes and

impulse over voltages. On polymer brackets, the use

of arresters is only possible when the arresters are

grounded, i.e., when dealing with different-potential

parts of the overhead line. An increase in overhead

line reliability can be achieved by combined

insulation (polymer bracket and polymer insulators)

with the use of surge arresters.

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Arai, H., Fujita, H., Ono, Yu., 2018. Effect Evaluation of

Lightning Protection Measures on Train Detectors for

Level Crossing System. 34th International Conference

on Lightning Protection (ICLP).

Dev Paul, P. E., 2005. Lightning Protection Analysis of

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Systems Technical Conference on Industrial and

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Ivanov, D., Skornyakov, V., Savelieva, I., Korotkikh, M.,

Shestakov, V., Uhrlandt, D., Podporkin, G., 2018.

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Table 3: Test results of the discharge performance of the system “arrester-polymer bracket” system.

Insulation

rod distance L, mm

Test with insulator,

Voltage application to

the rod,

imp

, kV

Test without insulator,

Voltage applied to the

rod,

imp

, kV

Test without insulator,

Voltage applied to

the conductor

imp

, kV

0 130 - -

70 167 - -

90 166 - -

100 167 145 -

200 - 175 205

TLC2M 2022 - INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE TLC2M TRANSPORT: LOGISTICS,

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with Actual Observed Result. 34th International

Conference on Lightning Protection (ICLP).

Podporkin, G. V., 2020. Improvement of Overhead

Transmission Lines Lightning Protection by Line

Arresters with Separate Groundings and Shielding

Wires Fixed at Insulation Racks. Lecture Notes in

Electrical Engineering 598, pp. 1180-1191.

Podporkin, G., Enkin, E. Yu., Belko, O. D., Pilschikov, V.

E., 2019. Multi-Chamber Disc-Type Lightning Arrester

for 13.8 kV Overhead Lines Protection. 11th Asia-

Pacific International Conference on Lightning (APL).

12-14 June 2019.

Zielenkiewicz, M., Maksimowicz, T., Burak-Romanowski,

R., 2018. The protection of DC railway traction power

supply systems against direct lightning strike. 34th

International Conference on Lightning Protection

(ICLP), pp. 1-6.

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