Miniature Circuit Breakers (MCB) Multi 9

1
Miniature Circuit Breakers (MCB)Multi 9
2
Definition
Main functions

• Symbol

• 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)

Miniature circuit switch trip unit breaker
(MCB) 4
3
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
4
Definition
Main performances

• It has standardized modular dimensions
• 125Ao 50 kA o 440 V CA

It fits in your pocket... 4
5
Definition

• Multi 9 standardo Multi 9 switchgear comes in
  9 mm pitch 4

• The modular design meets 2 criteria
• o 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

44 maxi
21.3
81
45maxi
35
width
60
10 maxi
symmetrical rail
external part
depth
6
The technology
Active parts
C60N
NC100 / NC125
terminal
terminal
bimetral strip
fixed contact
movingcontact
strip braid
moving contact
strip braid
magnetictrip
magnetic trip
strip braid
bimetal strip
load side terminal
load side terminal
4
7
Overload protection

• A bimetal strip is used o to protect the
  cable against overloadso 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
8
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
LegendIn rated currentInd no tripping
currentId tripping current 4
I/In
In
Ind
Id
9
Overload protection

• Temperature derating o our circuit breakers
  do not have temperature compensationo if the
  calibration temperature is different from the
  ambient temperature derating is required

Simultaneous multi-pole tripping 4
10
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
11
Short-circuit protection
The arc in Multi 9 circuit breakers
NC45
NC100 / NC125
arcing horn
arcing horn
"By-pass" technique for the protection of
sensitive partsof the circuit breaker
DCbreaking is difficult
"By-pass" technique for the protection of
sensitive parts of the circuit breaker (magnetic
trip)
2 breaking techniques used by Multi 9 4
12
Short-circuit protection
Magnetic tripping curve
destruction of the solenoid
t (s)
tripping
no tripping
LegendInd no tripping currentId tripping
current
I/In
Ind
Id
Our curves are instantaneous tripping curves 4
13
The magnetic tripping levels with high inrush
currentlike LV/LV transformers

• C Curveo 5 and 10 In control and protection
  of circuits with high short-circuit current in
  industrial and domestic distributions
• D and K curves tripping betweno tripping 10
  to 14 In more particulary adopted for
  installations with high inrush currents like
  LV/LV transformers
• Z curveo 2.4 to 3.6 In protection
  against electronic circuits
• MA curveo 12 In protection only
  against short-circuit and high inrush
  currents such as motors, coil 4

• B curve
• o 3 and 5 In protectionlow short-circuit current
  generators

M
14
Marking

• Side panel marking

• Front panel marking

Circuit breaker marking is governed by strict
rules in accordance with the standards and
decisions made by the manufacturer 4
15
Choosing a circuit breaker
In conclusion

• A Multi 9 circuit breaker is determined byo
  ratingo breaking capacity
• number of poleso voltageo tripping curve
• standardo frequencyo type of load 4

16
Auxiliaries C60

• SD alarm switch
• MX OF shunt trip o MN undervoltage release

• 4 types of auxiliaries for our Multi 9 circuit
  breakerso OF indication switch

MXOF
OF
SD
C60
MN
44/3
51/3
54/3
52/3
53/3
54 mm maxi
The information is transmitted via a mechanical
link C60/NC100 and NC125 auxiliaries are not
compatible 4
17
Auxiliaries NC100 - NC125

• SD alarm switcho MX OF shunt trip o MN
  undervoltage release

• 4 types of auxiliaries for our Multi 9 circuit
  breakerso OF indication switch

NC100H
MXOF or Vigi
MN or
OF
SD
33/3
34/3
35/3
27/3
36/3
The information is transmitted via a mechanical
link C60/NC100 and NC125 auxiliaries are not
compatible 4
18
End presentation