11
10
Contact electromagnetic
field distribution
Magnetic quenching principle
Moving
contact
Fixed
contact
Arc is pushed into
arc extinguish
chamber by
magneto-mechanical
effect
Current limit type
Current limiting means to keep the short circuit current in the circuit being protected lower than
expected value. With the protection of current limit type Ex9M circuit breaker, the peak short
circuit current value and I
2
t energy will be significantly lowered in case of short circuit.
Current limiting can reduce the heat effect, electrodynamic effect and electromagnetic effect
of short circuit current. It can also reduce the damage caused by short circuit current to lines,
equipment and circuit breaker.
If the upstream circuit breaker is equipped with current limiting capability, which can lower the
requirements for the breaking capacity of downstream circuit breaker and achieving cascade
(backup) protection
If both the upstream and downstream circuit breakers are equipped with current limiting
capability, the system can provide selective protection, in which case only the closest circuit
breaker will be disconnected if fault occurs.
U type fixed contact design
The unique U type contact enables pre-breaking technology:
The pre-breaking technology means when the short circuit current goes through the contact
system, the electric force generated on the U type fixed contact and the moving contact are
repulsive; the bigger the current, the bigger the force, and the force is generated at the same
time as the short circuit current; before release, the electric repulsion force can break the fixed
and the moving contacts, increasing the equivalent resistance between them by extending the
arc, so that the increase of short circuit current is suppressed.
Double breaking point design
The unique double breaking point design can increase instantaneous arc resistance and arc
voltage, and significant lower current increase rate, which enhances the current limiting effect
of the pre-breaking technology; it can improve safety by lowering the harm and damage caused
by short circuit current to equipment and circuit; it also enables cascade which can reduce the
cost for downstream protection equipment.
Zero flashover
Electromagnetic field simulation analysis ensures the arc extinguishing capability of the circuit
breaker so as to achieve zero flashover.
We use comprehensive and advanced electromagnetic field software simulation technology
for the design of arc extinguish chamber and the fixed and moving contacts of the circuit
breaker, to make sure the generated arc is blown into the arc extinguish chamber instantly. By
using magnetic quenching method, we significantly improved the arc extinguishing capability
of the circuit breaker and further enhanced it’s current limiting capability.
Ｉ
Ｔ
Expected peak
Expected short
circuit current
Actual peak
Actual short circuit current
after current limiting
Energy after current
limiting
Ｉ
Ｉ
U type rejection circuit,
enhanced repulsion
force for fast breaking
of contact
Upper fixed contact
Force F1
Moving
contact
Lower fixed
contact
Force F2
Bearing type
The operating mechanism is a key component of the circuit breaker, the key technical parameters
and performance of the circuit breaker is closely related to the operating mechanism:
Rotary shaft is a key component of the circuit breaker:
Mechanical life (times)
Ex9M – a durable high-performance circuit breaker:
Service life of the circuit breaker
Breaking capacity of the circuit breaker
Breaking speed of the circuit breaker
Operating force of the circuit breaker
Operation reliability of the circuit breaker
It is a rotary part inside the circuit breaker, which will operate tens of thousands of times
It guarantees the synchronized disconnecting and connecting of the three phases (or four phases)
of the circuit breaker
The wear of the rotary shaft will affect the performance of other parts which can increase risks
Extend the service life of circuit breaker by times
2 times of standard, decrease the frequency for
replacement and cost for maintenance
Significantly improve the reliability of the product
The use of accessories is not affected by
operation times
Reliably improved breaking capacity: ensure
I
cs
=I
cu
, without derating in reverse wire entering application.
Increase breaking speed by times: breaking time < 2ms
Significantly decrease operating force: less than 3/5 of similar products
The friction between the rotary shaft of a traditional circuit breaker and its adjacent parts is
sliding friction, which can generate high frictional resistance and therefore cause larger wear to
the rotary shaft. This can be the biggest issue that limits the breaking speed and the service life
of the circuit breaker.
Noark developed a new type of rotary shaft that generate rolling friction which eliminated all
the issues that created by sliding friction and thus significantly improved the performance of the
circuit breaker.
Manual operation of Ex9M: easy and flexible
Electric operation of Ex9M: lower power consumption of motor
Model
Operating force
Ex9M1
Ex9M2
Ex9M3
Ex9M4
Ex9M5
Ex9M6
3p
4p
3p
4p
3p
4p
3p
4p
3p
4p
3p
4p
Making force (N)
44
46
55
82
120
160
160
200
160
200
250
255
Breaking force (N)
24
24
39
55
110
150
150
195
150
195
170
175
Re-trip force (N)
36
38
36
54
150
220
165
215
165
215
260
265
Electrical life (times)
Features
Features
8000
4000
4000
15000
2500
6000
3000
2000
Ex9M6
Ex9M5
Ex9M4
Ex9M3
Ex9M2
Ex9M1
Ex9M6
Ex9M5
Ex9M4
Ex9M3
Ex9M2
Ex9M1
