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Miniature Circuit Breakers (MCB) Multi 9

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

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Miniature Circuit Breakers (MCB) Multi 9

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  1. Miniature Circuit Breakers (MCB)Multi 9

  2. 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

  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 standardoMulti 9 switchgear comes in 9 mm pitch 4 • The modular design meets 2 criteria: omounting 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 10 maxi 60 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:oto protect the cable against overloadso symbol: • principle of the bimetal: in a Multi 9 circuit breaker4 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 Legend:In = rated currentInd = no tripping currentId = tripping current 4 In Ind Id I/In

  9. Overload protection • Temperature deratingoour circuit breakers do not have temperature compensationoif 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 Legend:Ind = no tripping currentId = tripping current Ind Id I/In Our curves are instantaneous tripping curves 4

  13. G The magnetic tripping levels with high inrush current:like LV/LV transformers • B curve o 3 and 5 In protectionlow short-circuit current generators • 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 M

  14. 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

  15. Choosing a circuit breaker In conclusion • A Multi 9 circuit breaker is determined by:o 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 breakersoOF: indication switch MN C60 MX+OF SD OF 44/3 54/3 51/3 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 breakersoOF: indication switch MN or NC100H MX+OF or Vigi SD OF 33/3 34/3 27/3 35/3 36/3 The information is transmitted via a mechanical link C60/NC100 and NC125 auxiliaries are not compatible 4

  18. End presentation

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