38
Design and specifications are subject to change without notice
01/2008
Fig. 42 Inspection of the arc chute
6.1.4 Inspection of the contact system
Pay attention to the warnings, Section 1!
A) Remove the arc chute
•
[Fig. 41]. Loosen the clamping screws (3) and (4), using
SW 5 hexagon wrench and take off the arch chute (1)
from the adapter (2).
B) Remove the arc chute adapter
•
[Fig. 43]. For dismantling the arc chute adapter loosen
and pull out the four upright screws (1) using SW5 tool.
Pay attention that no screws or washers fall inside the
breaker !
•
[Fig. 43]. Draw aside and lift off both parings of
adapter (2). Then pull out two protective walls (3).
Fig. 43 Adapter and protective walls
C) Check the protective walls
•
[Fig. 44]. The material burn out on the protective walls
(5) shall not exceed 1mm [0,04in] at any place.
Fig. 44 Checking the contact system
D) Check the arc runners
•
[Fig. 44]. The arc runners should not be burned more
30% of its total cross section. Pay particular attention
to the area around arc runner bend (3) and at contact
point with pre-arcing contact (2).
E) Check the pre-arcing contact
•
[Fig. 44]. Wear of the pre-arcing contact (1) must not
exceed 2mm [0,08in] of its depth. Replace the pre-
arcing contact in that case. If the burn out exceeds
4mm [0,16in], it might lead to major contact system’s
failure.
F) Check the main contacts
•
[Fig. 44]. The main contacts (4) shell not shown any
particular signs of material erosion, since the arc is ig-
nited between the pre-arcing contacts. It means, that
for rated and overload currents there is no erosion of
main contacts.
•
Erosion of main contacts can take place only in case
of excessively worn, highly burned pre-arcing contact
or during very high short circuit currents. In that case
wear must not exceed 1mm [0,04in].
G) Install the adapter
•
[Fig. 43]. Install the two protective walls (3). Use new
ones if necessary. Install two parings of adapter (2)
and tighten screws (1) use 5Nm [44lbf*in].
H) Install the arc chute
•
[Fig. 41]. Put in arc chute (1) into adapter (2).
•
[Fig. 41]. Tighten front- and backside connections of
the arc runners (3), including lock washer; use 10Nm
[88lbf*in].
•
[Fig. 41]. Tighten front- and backside of the arc chute
connections (4), including flat washers; use 5Nm
[44lbf*in].
1
3
2
4
2
1
3
1
