0HK.412.530SM
LW36A-126/145
High Voltage SF6 AC Circuit Breaker
10/30
When the circuit breaker received an order, the rigidity movement parts which consist by cylinder,
moving arc contact, tie bar will move down under the operation of switch off spring. In the movement,
fixed main contact breakaway with moving main contact, current transfer to two closed arc contacts,
then the arc contact breakaway come into being arc.
When breaking short circuit current, if breaking heavy current, arc energy is big of between arc
contacts, arc zone’s thermal current inrush into thermal expansion chamber and exchange thermal,
come into being low temperature and high pressure gas; here, because the thermal expansion
chamber pressure big than plenum chamber, the non-return valve close. When the current is exceed
zero, the high pressure gas in the thermal chamber blow to fracture to extinguish arc. In switching off,
the plenum chamber’s gas pressure was compressed at begin, when the gas pressure up to a stated
value, the bottom spring pressure relief valve opening, pressure gas and relief gas at same time, so the
mechanism not have to conquer more pressure gas counterforce, thereby reduced operating power
greatly.
（
see drawing 5B
）
。
If breaking low current
（
usually is less than thousands ampere
）
，
due to arc energy is small, the pressure
in thermal expansion chamber is low. Here, the plenum chamber’s pressure is higher than thermal
expansion chamber, non-return valve opening, the compressed gas blow to fracture, when the current
exceed zero, make the arc extinguish.
（
see drawing 5C
）
。
2
．
6 Spring operating mechanism
This operation instruction introduced commonly of CT30 spring operating mechanism’s configuration
and principle, the detailed information you can refer to
《
operation instruction of CT30 spring
operating mechanism
》
.
The spring operating mechanism install in control box, the operating principle see drawing 6.
2
．
6
．
1 Energy store of switch on spring
AC/DC motor drive pawl axis circumrotate, 90°change transfer to big pawl and small pawl, drive
ratchet wheel circumrotate, make the switch on spring compress to store energy by tie bar; past the
dead center position, motor was cut power supply by a sensitive switch.
（
motor is provided with over
current protection and force cut power supply in 15 seconds.
）
Ratchet wheel axis is given a
counter-clockwise running moment by switch on spring.
2
．
6
．
2 Switch on operating
The switch on coil after electrified, drive switch on detent; the switch on detent to circumrotate
clockwise, release switch on keep detent; jack up B pin to release ratchet wheel, the kept switch on
spring release energy to drive cam circumrotate.
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