{"id":4241,"date":"2026-09-25T00:00:00","date_gmt":"2026-09-25T00:00:00","guid":{"rendered":"https:\/\/chac-electric.com\/?p=4241"},"modified":"2026-10-19T03:36:42","modified_gmt":"2026-10-19T03:36:42","slug":"moteur-de-protection-3-poles-100-amperes","status":"publish","type":"post","link":"https:\/\/chac-electric.com\/fr\/blog\/3-pole-100-amp-mcb\/","title":{"rendered":"MCB \u00e0 3 p\u00f4les de 100 amp\u00e8res"},"content":{"rendered":"

A MCB \u00e0 3 p\u00f4les de 100 amp\u00e8res<\/strong> is a three-pole miniature circuit breaker with a declared current rating of 100 A per pole under its specified conditions. It does not create a single 300 A circuit. Selection requires the line-to-line voltage, current in each phase, available fault current and the exact device configuration. A suitable current rating alone does not establish motor protection, neutral switching or compatibility with a distribution board.<\/p>\n

\"3<\/p>\n

Read 100 A as a per-phase rating<\/h2>\n

Three-phase currents flow in separate conductors. If each phase carries 80 A, it is not correct to describe the breaker as carrying 240 A against a 100 A limit. Conversely, lightly loaded phases do not compensate for an overloaded phase. Review the load schedule and the most heavily loaded conductor rather than averaging the three readings to justify the selection.<\/p>\n

Power and current are also different quantities. Converting a three-phase power demand to current requires the supply voltage and relevant power-factor or efficiency assumptions. Use the equipment\u2019s input-current information where available, especially for motors and electronic loads, rather than dividing watts by a single phase voltage.<\/p>\n

Confirm the neutral and common-trip arrangement<\/h2>\n

A standard three-pole arrangement connects the three phases; it does not provide an extra neutral pole. A circuit may include a continuous neutral where permitted, but a requirement to disconnect or protect that conductor must be addressed explicitly in the design. Do not put a phase through an unprotected neutral pole as a shortcut.<\/p>\n

Specify the manufacturer\u2019s common-trip construction. Three separate single-pole devices placed next to one another are not automatically equivalent. The related three-phase miniature circuit breaker guide<\/a> explains what the linked device does and which protection functions still require separate consideration.<\/p>\n

Check the conductor, busbar and enclosure at 100 A<\/h2>\n

At this rating, terminations and assembly conditions deserve as much attention as the breaker. Verify the cable ampacity after correction factors, the terminal conductor range, approved busbar system and enclosure temperature limits. The IEC-based selection relationship in the Electrical Installation Guide remains IB \u2264 In \u2264 Iz; a 100 A label does not override a lower cable or assembly limit.<\/p>\n

For an actual product review, compare the CQB2-125 miniature circuit breaker<\/a> information with CHAC\u2019s MCB product range<\/a>. Confirm the exact 100 A three-pole variant and its technical documentation. A larger catalogue family is a starting point, not evidence that every configuration is available or approved.<\/p>\n

\"CHAC<\/p>\n

Use the fault study to check breaking capacity<\/h2>\n

Le three-phase fault current<\/strong> at the board must be considered independently of the normal operating current. Verify the breaker\u2019s declared short-circuit capacity at the actual voltage and pole arrangement. If backup protection is proposed, obtain the specific tested combination and observe the applicable installation rules; do not infer protection from the upstream device\u2019s larger ampere rating.<\/p>\n

Selectivity is another separate question. Two breakers may both interrupt the fault safely yet trip together, shutting down more of the installation than intended. Use the manufacturer\u2019s coordination data and the project\u2019s continuity requirements to assess that consequence.<\/p>\n

Add motor-specific protection where the load requires it<\/h2>\n

A three-pole distribution MCB does not automatically detect phase loss, phase reversal or damaging imbalance. A motor circuit may need an overload device, a phase-monitoring function and suitable coordination with the contactor. Schneider Electric\u2019s Micrologic FAQ illustrates that even more elaborate breaker systems have model-specific limits on phase-loss detection.<\/p>\n

Choose the Curve de d\u00e9placement de la MCB<\/strong> from the documented starting duty and required fault-clearing performance. A C-curve is not a universal motor setting. Keep startup behavior, overload protection and short-circuit interruption as distinct checks so that a device which tolerates starting current is not mistaken for a complete motor-protection scheme.<\/p>\n

What must be confirmed for a 100 A three-pole feeder?<\/h2>\n\n\n\n\n\n\n\n\n
Decision<\/th>\nRequired check<\/th>\nErreur courante<\/th>\n<\/tr>\n<\/thead>\n
Normal current<\/td>\nEach phase and corrected cable ampacity<\/td>\nAdding pole ratings to get 300 A<\/td>\n<\/tr>\n
Responsabilit\u00e9 p\u00e9nale<\/td>\nAvailable current at the declared voltage<\/td>\nChoosing by amperes only<\/td>\n<\/tr>\n
Neutral<\/td>\nRequired switching and protection arrangement<\/td>\nAssuming a fourth pole exists<\/td>\n<\/tr>\n
Motor duty<\/td>\nStarting current, overload and phase monitoring<\/td>\nTreating common trip as phase-loss detection<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n

Foire aux questions<\/h2>\n

O\u00f9 est utilis\u00e9 un disjoncteur \u00e0 trois p\u00f4les de 100 A MCB ?<\/h3>\n

Les applications courantes comprennent les alimentations triphas\u00e9es, les petites tableaux de distribution et les circuits d\u2019\u00e9quipement dans les plages de tension et de failles de l\u2019appareil. L\u2019application doit respecter les limites fix\u00e9es par les codes locaux et le fabricant.<\/p>\n

Est-ce que la courbe C est toujours la bonne pour un moteur ?<\/h3>\n

Pas toujours. Une courbe C peut tol\u00e9rer une surcharge mod\u00e9r\u00e9e, mais la protection du moteur n\u00e9cessite souvent un protecteur d\u00e9di\u00e9 et une coordination de la surcharge. Utilisez une valeur de courant de d\u00e9marrage mesur\u00e9e ou document\u00e9e.<\/p>\n

Un MCB \u00e0 3 p\u00f4les peut-il passer en phase neutre ?<\/h3>\n

Un appareil standard \u00e0 trois p\u00f4les ouvre les trois phases. Si un branchement neutre est n\u00e9cessaire, sp\u00e9cifiez l\u2019arrangement correct \u00e0 quatre p\u00f4les ou \u00e0 connexion.<\/p>\n

Comment est-il install\u00e9 un disjoncteur \u00e0 rainure DIN?<\/h3>\n

Qualified personnel should follow the exact mounting, terminal, line\/load and tightening instructions. Perform the installation tests required by the adopted rules and commissioning plan; do not improvise a short-circuit test.<\/p>\n

Is a 3-phase breaker rating per phase?<\/h3>\n

Yes, the declared current applies to each pole under the stated conditions. A 100 A three-pole breaker is not a 300 A single-path device, and the least-loaded phase does not offset an overload on another phase.<\/p>\n

How do I calculate an MCB rating for a 3-phase circuit?<\/h3>\n

Determine the load current in each phase using the equipment input data and supply conditions. Then apply the adopted design rules, conductor correction factors, starting-duty review and fault-current check. Round-up arithmetic alone cannot establish the correct protective-device rating.<\/p>\n<\/section>\n

R\u00e9f\u00e9rences<\/h2>\n