ABB SF6 LTB 245E1 BLG 1002A, Product Manual

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Description Product Description
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1HSB435455-2 enrev1
1.2 The circuit-breaker’s gas system
The circuit-breaker poles are permanently filled with SF
6
gas at a pressure of
0.7 MPa abs at 20
°
C on circuit-breakers whose performance is limited by a lowest
ambient temperature of
≥
-30
°
C.
On circuit-breakers whose ambient temperature is
≥
-40
°
C the circuit-breaker is
filled to a pressure of 0.5 MPa abs at 20
°
C. On circuit- breakers whose ambient
temperature is
≥
-55
°
C the circuit-breaker is filled with a mixture of SF
6
gas and N
2
gas or CF
4
gas at a pressure of 0.7 MPa abs at 20
°
C. The poles are fitted with
density monitors to monitor the pressure.
1.2.1 Opening and closing
The circuit-breaker poles work according to the Auto-Puffer
TM
- principle with a
puffer cylinder (1) divided into two chambers. An Auto-Puffer
TM
section (2) and a
compression section (3).
When the normal operating currents are cut
the SF
6
gas is compressed in the
compression section to an over-pressure.
When the arcing contacts part, the gas in
the compression section flows out and
extinguishes the arc at the passage trough
zero.
When the short-circuit currents are cut the
requisite extinguishing pressure is built-up
in the Auto-Puffer
TM
section by heating the
arc. In this way a pressure increase is
achieved with energy from the arc and no
extra energy is required from the operating
mechanism.
On closing the puffer cylinder slides
upwards, the contacts engage one another
and the puffer cylinder is refilled with gas.
Figure 1-2. Circuit-breaker pole in the Close position.
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B10097