Siemens SENTRON 3WL Reference Manual page 21

3WL Air Circuit Breakers/Non-Automatic Air Circuit Breakers up to 6300 A (AC)
SENTRON 3WL for DC applications
This version of the 3WL non-automatic air circuit breaker is sui-
table for direct current applications. The external protective de-
vice DIGmat S100 provides adjustable overload and short-
circuit protection for the SENTRON 3WL non-automatic air circuit
breaker.
This is based on the measuring chain of a shunt resistor and the
DIGmat S100 tripping unit. Shunt resistors are available for
1000 A, 2000 A and 4000 A (special ranges on request). They
are in accordance with DIN 43703 and have a class accuracy
of 0.5.
A measuring-circuit voltage of 60 mV DC is picked off for rated
current I .
n
The measuring-circuit voltage is a linear image of the primary
current.
The DIGmat S100 tripping unit monitors the image of the primary
current thus supplied and compares it with the tripping cha-
racteristic curve set on the device. The parameter settings on
the DIGmat S100 apply also for DC feedbacks.
Reversing duty is possible therefore.
The tripping characteristic curve is determined and described
by the following variables:
• Overload protection:
= 0.4 ... 1.0 I
Setting range I
R
2
The curve has a I t characteristic.
The tripping time t is selectable between 2 and 10 s, with t
R
defined for 6 × I .
R
■
Configuration
Mutual mechanical circuit breaker interlocking
The module for mutual mechanical interlocking can be used for
one or two SENTRON 3WL circuit breakers and can be adapted
easily to the corresponding versions. The fixed-mounted and
withdrawable circuit breaker versions are fully compatible and
can therefore be used in a mixed configuration in an installation.
This also applies to 3WN6 circuit breakers.
The circuit breakers can be mounted alongside each other or
one above the other, whereby the distance of the circuit breakers
is determined solely by the length of the Bowden wire (lengths:
2 m/3 m/4.5 m). Interlock signals are looped through using the
Bowden wires. Interlocking is only effective in the connected po-
sition in the case of withdrawable circuit breakers. The mechani-
cal endurance of the Bowden cables is 10 000 operating cycles.
Minimum requirements must be fulfilled in the switchgear for the
interlocking to function:
• Bowden wires must be installed as far as possible in a straight
line with minimum bending.
Mutual mechanical interlocking of circuit breakers – examples
Mutual interlocking of two
circuit breakers
G
S S
1 2
NSE01041
n
Interlocking between three
circuit breakers
S S
1 3
S
2 S
1
NSE01043
NSE01042
3WL Air Circuit Breakers
DIGmat S100
• Short-circuit protection:
Setting range I = 1.25 × I
i
If the set value is exceeded, tripping occurs in less than
50 ms.
I = Rated current of the circuit breaker
n
I = Set current value of the adjustable overload release
R
t = Assigned tripping time of the overload trip
R
I = Instantaneous tripping current of the adjustable short-
i
circuit releases
The components are available only from the company
R
mat – Maschinen- und Anlagentechnik
(for address see "Appendix" => "External Partners").
• The bending radii of the Bowden wire must be greater than
500 mm.
• The sum of all bending angles along the Bowden wire must not
exceed 640°.
• In a vertical arrangement of circuit breakers to be interlocked,
the interlocking mechanisms must be in line.
• Circuit breakers to be interlocked must be arranged so that
Bowden cables can be optimally installed in compliance with
the conditions mentioned in the above points.
• The installed Bowden wire must be fixed (with cable ties or the
like) before the interlock is adjusted.
• Select the width of switchgear cubicle to allow enough free-
dom of movement for adjusting the interlock!
• Openings and cut-outs in system elements must be designed
so that Bowden wires are not changed in direction or obs-
tructed when they are passed through.
Mutual interlocking of three
circuit breakers
G
S S
1 2
S S
2 3
NSE01044
General data
up to max. 4 × I
R n
Interlocking of three circuit
breakers, two of them mutual
G
S S
1 3
S
3
S
2
NSE01045
Siemens · 2009 21