Transcript Miniature Circuit Breakers (MCB)

Miniature Circuit Breakers (MCB)
Multi 9
Definition
Main functions
 Protect cables against
overloads and short
circuits
 Let the current flow
without overheating on
cables
 Open and close a circuit
under rated current
 Protect against insulation
faults (see earth leakage
protection module)
 Symbol
Miniature circuit = switch + trip unit breaker (MCB) 4
Customer Training - Freddy Suhartono - April 2000 - English
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Definition
A Multi 9 circuit breaker has:
 A mechanical system to open and close the
circuit
 A bimetal strip to act against overloads
 A magnetic trip to act against short circuits
Miniature circuit = switch + trip unit breaker (MCB) 4
Customer Training - Freddy Suhartono - April 2000 - English
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Definition
Main performances
 It has standardized modular dimensions
  125A
  50 kA
  440 V CA
It fits in your pocket... 4
Customer Training - Freddy Suhartono - April 2000 - English
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Definition
 The modular design meets 2
criteria:
 mounting on a 35 mm
symmetrical rail
 dimensions
- modules in widths of
17.5 mm + 0.5 - 0
- external part = 45 mm
- depth between 55 and 70 mm
 Multi 9 standard
 Multi 9 switchgear comes in 9 mm pitch 4
44 maxi
21.3
81
45
maxi
width
symmetrical
rail
depth
Customer Training - Freddy Suhartono - April 2000 - English
external
part
10 maxi
35
60
5
The technology
Active parts
C60N
NC100 / NC125
terminal
terminal
bimetral strip
fixed contact
strip braid
moving
contact
strip braid
moving
contact
magnetic trip
load side
terminal
magnetic
trip
strip braid
bimetal strip
load side
terminal
4
Customer Training - Freddy Suhartono - April 2000 - English
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Overload protection
 A bimetal strip is used:
 to protect the cable against overloads
 symbol:
 principle of the bimetal: in a Multi 9 circuit
breaker 4
NC45
NC100 / NC125
bimetal
tripping bar
tripping bar
bimetal
screw
calibration
strip
braid
Customer Training - Freddy Suhartono - April 2000 - English
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Overload protection
 Thermal tripping curve
 the "thermal" part of the
tripping curve must be in
accordance with the
standard
t (s)
tripping
no
tripping
destruction
of bimetal
accuracy
Legend:
In = rated current
Ind = no tripping current
Id = tripping current 4
Customer Training - Freddy Suhartono - April 2000 - English
In
Ind Id
I/In
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Overload protection
 Temperature derating
 our circuit breakers do not have temperature
compensation
 if the calibration temperature is different from
the ambient temperature: derating is required
Simultaneous multi-pole tripping 4
Customer Training - Freddy Suhartono - April 2000 - English
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Short-circuit protection
Short-circuit current is given as RMS or peak
(Isc or Îsc)
RMS = Root Mean Square in symmetrical DC
(with PF = I)
Short-circuit protection must limit thermal stress in the
cable in order to prevent cable damage (which may
reach vaporization of the copper in some cases)
Comments slide 29
Customer Training - Freddy Suhartono - April 2000 - English
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Short-circuit protection
The arc in Multi 9 circuit breakers
NC45
NC100 / NC125
arcing
horn
"By-pass" technique for the
protection of sensitive parts
of the circuit breaker DC
breaking is difficult
Customer Training - Freddy Suhartono - April 2000 - English
arcing
horn
"By-pass" technique for the protection of
sensitive parts of the circuit breaker (magnetic
trip)
2 breaking techniques used by Multi 9 4
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Short-circuit protection
Magnetic tripping curve
t (s)
destruction
of the solenoid
tripping
no
tripping
Legend:
Ind = no tripping current
Id = tripping current
Ind Id
I/In
Our curves are instantaneous tripping curves 4
Customer Training - Freddy Suhartono - April 2000 - English
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The magnetic tripping levels with high inrush
current:
like LV/LV transformers
 C Curve
 5 and 10 In control and protection of
circuits with high short-circuit current
in industrial and domestic distributions
 D and K curves tripping betwen
 tripping: 10 to 14 In; more particulary
adopted for installations with high
inrush currents like LV/LV transformers
 B curve
 3 and 5 In protection
low short-circuit current
generators
G
Customer Training - Freddy Suhartono - April 2000 - English
 Z curve
 2.4 to 3.6 In protection against
electronic circuits
 MA curve
 12 In; protection only against
short-circuit and high inrush currents
such as motors, coil 4
M
13
Marking
 Front panel marking:
 Side panel marking:
Circuit breaker marking is governed by strict
rules in accordance with the standards and
decisions made by the manufacturer 4
Customer Training - Freddy Suhartono - April 2000 - English
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Choosing a circuit breaker
In conclusion
 A Multi 9 circuit breaker is determined by:
 rating
 breaking capacity
 number of poles
 voltage
 tripping curve
 standard
 frequency
 type of load 4
Customer Training - Freddy Suhartono - April 2000 - English
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Auxiliaries: C60
 SD: alarm switch
 MX + OF: shunt trip
 MN: undervoltage release
 4 types of auxiliaries for our
Multi 9 circuit breakers
 OF: indication switch
SD
MX+OF
MN
C60
51/3
52/3
54/3
53/3
44/3
OF
54 mm maxi
The information is transmitted via a
mechanical link C60/NC100 and NC125
auxiliaries are not compatible 4
Customer Training - Freddy Suhartono - April 2000 - English
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Auxiliaries: NC100 - NC125
 4 types of auxiliaries for our
 SD: alarm switch
 MX + OF: shunt trip
 MN: undervoltage release
MN or MX+OF
or Vigi
27/3
35/3
NC100H
SD
34/3
33/3
OF
36/3
Multi 9 circuit breakers
 OF: indication switch
The information is transmitted via a
mechanical link C60/NC100 and NC125
auxiliaries are not compatible 4
Customer Training - Freddy Suhartono - April 2000 - English
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End presentation
Customer Training - Freddy Suhartono - April 2000 - English
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