vadodara institute of engineering,kotambi name:nafiskhanpathan(13elee181) bariya vipul(13elee182)...
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Vadodara institute of engineering,kotambi
NAME:NAFISKHANPATHAN(13ELEE181)
BARIYA VIPUL(13ELEE182)
PATEL AMIT(13ELEE180)
BRANCH:EE-2
PPT OF EEE
Protect cables againstoverloads 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 leakageprotection module)
DefinitionMain functions
Miniature circuit = switch + trip unit breaker (MCB)
Symbol
A mechanical system to open and close the circuit
A bimetal strip to act against overloads
A magnetic trip to act against short circuits
DefinitionA Multi 9 circuit breaker has:
Miniature circuit = switch + trip unit breaker (MCB)
It has standardized modular dimensions
125A
50 kA
440 V CA
DefinitionMain performances
It fits in your pocket...
Definition
Multi 9 standard Multi 9 switchgear comes in 9 mm pitch
width
symmetricalrail
externalpartdepth
6010 maxi
3545maxi
44 maxi
21.3
81
The modular design meets 2 criteria:
mounting on a 35 mmsymmetrical rail
dimensions- modules in widths of 17.5 mm + 0.5 - 0- external part = 45 mm- depth between 55 and 70 mm
The technologyActive parts
C60N NC100 / NC125
terminal
fixed contact
movingcontact
strip braid
magnetictrip
load side terminal
terminal
bimetral strip
strip braid
movingcontact
magnetic trip
load side terminal
strip braidbimetal strip
Overload protection
bimetal
tripping barbimetal
tripping bar
screwcalibration
stripbraid
NC45 NC100 / NC125
A bimetal strip is used: to protect the cable against overloadssymbol: principle of the bimetal: in a Multi 9 circuit
breaker
Thermal tripping curve
the "thermal" part of thetripping curve must be
inaccordance with the
standard
Overload protection
Legend:In = rated currentInd = no tripping currentId = tripping current
tripping
notripping
destructionof bimetal
accuracy
t (s)
I/InIn Ind Id
Overload protection
Simultaneous multi-pole tripping
Temperature derating our circuit breakers do not have temperature
compensation if the calibration temperature is different from
the ambient temperature: derating is required
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
Short-circuit protection
"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)
The arc in Multi 9 circuit breakers
2 breaking techniques used by Multi 9
arcinghorn arcing
horn
NC45 NC100 / NC125
Short-circuit protectionMagnetic tripping curve
Our curves are instantaneous tripping curves
Legend:Ind = no tripping currentId = tripping current
destructionof the solenoid
trippingnotripping
t (s)
I/InInd Id
B curve 3 and 5 In protection
low short-circuit current generators
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 currentin industrial and domestic distributions
D and K curves tripping betwen tripping: 10 to 14 In; more particulary
adopted for installations with highinrush currents like LV/LV transformers
Z curve 2.4 to 3.6 In protection against
electronic circuits
MA curve 12 In; protection only against
short-circuit and high inrush currentssuch as motors, coil
G
M
Side panel marking:
Marking
Front panel marking:
Circuit breaker marking is governed by strict rules in accordance with the standards and decisions made by the manufacturer
Choosing a circuit breakerIn conclusion
A Multi 9 circuit breaker is determined by:
rating
breaking capacity number of poles
voltage
tripping curve standard
frequency
type of load
Auxiliaries: C60
SD: alarm switch MX + OF: shunt trip MN: undervoltage release
The information is transmitted via a mechanical link C60/NC100 and NC125 auxiliaries are not compatible
54 mm maxi
4 types of auxiliaries for ourMulti 9 circuit breakers
OF: indication switch
MX+OFOF SD C60
44/3
MN
51/3
52/3
54/3
53/3
Auxiliaries: NC100 - NC125
The information is transmitted via a mechanical link C60/NC100 and NC125 auxiliaries are not compatible
NC100H MX+OFor Vigi
MN orOF SD
33/3
34/3
35/3
36/327
/3
SD: alarm switch MX + OF: shunt trip MN: undervoltage release
4 types of auxiliaries for ourMulti 9 circuit breakers
OF: indication switch