eb - Elektrische Bahnen Bahnenergieversorgungssystem der DB erneut bestätigt (Vorschau)

Pantographs
The step structure allows to measure wire wear by
calculating the difference of height of each part of
the contact wire surface.
The wire tested was a standard grooved AC-120
according EN 50149 on both test rigs.
In total nine different strip materials, four plain
and five impregnated ones with a copper content of
20 up to 48 % in mass were tested.
Figure 9:
Principle of wear measurement at Hoffmann test bench.
3 Parts of project
3.1 Comparison of results gained at the
two test rigs
The objective of this first series of tests was to isolate
the contribution from the carbon material itself
in the phenomenon of wear without action of the
electric arcs.
The following common test routine was established
for each bench with the identical conditions
also in order to compare results between the two
test rigs:
• Width of carbon strip samples 35 mm
• Specific contact force
3,1 N/mm
• Specific current
8 A/mm
• Speed
180 km/h
Force and current conditions were retained as the
extreme values given by the questionnaire.
Speed is the maximum value generating only
little arcing level on each test bench.
3
mm 3 /km
2,5
wear of contact strips →
2
1,5
1
0,5
0
B plain A imp1 A plain B imp A imp2 C imp
20% 26% 25% 35%
Figure 10:
Wear of contact strips – Comparison between test rigs.
average value +
standard deviation
Polimi (1st series)
Hoffmann
(1st series)
Hoffmann
(2nd series)
average value -
standard deviation
3.2 Materials of the contact strips
The tests related to samples provided by two European
manufacturers. The materials called A and B
exist in the versions
• plain carbon, called A plain and B plain
• and impregnated carbon called A imp and B imp
+ copper content in % of weight
That means carbons of type A and B have seen an additional
industrial treatment of metal impregnation.
The material C, very common in Europe, will be also
tested but only in its impregnated version with 35 %
of metal C imp 35 %, the pure version not being on
market.
1,5
mm² / 10 6
→
wear of contact wire
related to CSP
1
0,5
0
B plain A imp1 A plain B imp A imp2 C imp
20% 26% 25% 35%
average value +
standard deviation
Polimi (1st series)
Hoffmann
(1st series)
Hoffmann
(2nd series)
average value -
standard deviation
Figure 11:
Wear of contact wires – Comparison between test rigs.
Hoffmann and Polimi 1 st series, means that the tests of a contact strip were carried out on the
patina deposited by the strip of the previous test; Hoffmann 2 nd series means that the test of
contact strip is carried out on a machined wire
3.3 Duration of a test
The duration of a test or more precisely the number
of contact strip passages is one of the more important
parameter to be considered.
Actually, a minimum test duration is necessary to
ensure that mechanical and electrical energy dissipated
in the interface area between the materials in
contact and equilibrium is reached. That duration
depends on the test bench design but also may vary
from one material to another.
Therefore, arbitrarily setting identical test durations
for the test materials may lead to overestimating
or underestimating wear speeds.
Hence, electric wear was appreciated by seeking
the conditions for which the wear rate of the pure
copper wire reached a constant value characteristic
190 111 (2013) Heft 3