Air Circuit Breaker Supplier
Air Circuit Breakers for Selective Main Power Protection
Select a low-voltage ACB from the source, busbar, fault level and coordination study. SENTOP supports fixed and draw-out model matching for main incomers, bus couplers and high-current feeders, including electronic trip units, accessories, documents and bulk supply.
What an ACB Does
Control and protect the main low-voltage power path
An air circuit breaker is commonly used in low-voltage switchboards for overload and short-circuit protection, switching and isolation where the exact model is suitable. Its maintainable construction, electronic protection, short-time delay capability and draw-out option can support selective main-distribution design.
The ACB must be selected as part of the switchboard. Source data, busbar rating, prospective fault current, cable or busway, downstream protection, earthing, enclosure form, ventilation and operating procedure all affect the final configuration.
Proteção principal
The electronic trip unit monitors long-time overload and short-circuit conditions. Exact functions and settings depend on the selected trip unit.
Selective delay
Short-time pickup and delay can allow a downstream breaker to clear a fault first, subject to verified selectivity and short-time withstand data.
Operação do painel de controle
Stored-energy mechanisms, electrical closing, shunt trip, undervoltage release and position contacts support local and remote operation.
Continuidade do serviço
A draw-out breaker can provide connected, test and disconnected positions, but the cradle, interlocks and maintenance procedure must match the switchboard.
ACB Selection Process
Choose the breaker from the one-line diagram
An accurate ACB request connects the source, switchboard, busbar, fault level, protection study, operating mechanism and destination requirements to one complete breaker configuration.
Source and system data
Confirm transformer or generator rating, Voltagem AC, frequency, phase arrangement, earthing system and the ACB position on the one-line diagram.
Frame, sensor and rated current
Separate frame size, rated current, current sensor or rating plug and long-time setting. Check continuous load, busbar capacity, ambient temperature and enclosure heating.
Icu, Ics and Icw
Match breaking capacities and short-time withstand to the prospective fault current, operating voltage, delay time and required service continuity.
Funções de viagem eletrônica
Define long-time, short-time, instantaneous and ground-fault functions, setting ranges, time bands, zone-selective interlocking and any measurement needs.
Poles and neutral protection
Confirm 3P or 4P, neutral switching, neutral sensor rating, ground-fault sensing arrangement and compatibility with the earthing system.
Fixed or draw-out construction
Define breaker and cradle, connected/test/disconnected positions, front or rear busbar connections, door cutout, compartment depth and access for maintenance.
Mechanism, interlocks and documents
Review closing and opening coils, motor charging, auxiliary contacts, key or mechanical interlocks, communication, standard, approval scope and drawings.
ACB Product Directions
Choose construction from the switchboard duty
These directions organize an enquiry. Final selection depends on the complete breaker, cradle, trip unit, mechanism, busbar arrangement, interlocks, dimensions and approval scope.
ACB de tipo fixo
A breaker mounted directly in the switchboard for installations where compact construction is prioritized and withdrawal is not required.
Draw-Out Type ACB
A breaker and cradle arrangement for switchboards that need connected, test and disconnected positions for operation and maintenance.
Electronic Trip ACB
A direction for main distribution requiring adjustable long-time, short-time and instantaneous protection with optional ground-fault functions.
Large Frame Main ACB
A direction for transformer incomers, generator mains and bus couplers requiring high continuous current and verified short-time withstand.
Lembrete de substituição: an ACB replacement must match more than current and frame. Send the complete breaker and cradle codes, front and rear photos, trip unit, secondary terminal diagram, busbar layout, door cutout and interlock details.
ACB Trip Unit Selection
Match protection functions to the estudo de coordenação
The trip unit determines how the breaker responds to overload and short-circuit conditions. Available functions, setting ranges, tolerances and communication options vary by product family.
Overload and instantaneous
A basic electronic direction with long-time overload protection and instantaneous short-circuit operation.
Short-time coordination
Adds short-time pickup and delay so a downstream device can clear selected faults before the main ACB opens.
Ground fault and monitoring
Selected trip units add ground-fault protection, measurement, event records, alarms or communication for monitored switchboards.
Do not change a trip setting only to prevent nuisance operation. Confirm load behavior, conductor protection, fault-disconnection requirements and upstream/downstream coordination before adjustment.
ACB Ratings and IEC 60947-2
Read the nameplate as a complete rating set
IEC 60947-2 covers low-voltage circuit breakers within its stated scope. Market approval, standard edition and every rating still need verification against the exact product documentation.
In and frame rating
The operational current or trip rating is not automatically the same as the maximum current assigned to the physical frame.
Icu
Rated ultimate short-circuit breaking capacity at a stated operational voltage and specified test conditions.
Ics
Rated service short-circuit breaking capacity, commonly expressed as a percentage of Icu for the exact breaker.
Icw
Rated short-time withstand current where assigned, relevant to breakers and coordination arrangements designed for short-time delay.
Ue, ELA Éi, ELA Édiabinho
Operational, insulation and impulse withstand voltage values describe different aspects and are not interchangeable.
North American project reminder
IEC and UL rating systems, interruption values, application rules and approvals are not interchangeable by appearance. Confirm the exact UL listing, voltage, interrupting rating and installation role required for the destination.
| Item de seleção | O que verificar | Por que é importante |
|---|---|---|
| IEC 60947 2- | Certificate, exact model scope, edition, voltage and declared ratings | An ACB family name or similar front appearance does not establish conformity |
| Tensão operacional | AC or DC, Ue, frequency, voltage per pole and wiring arrangement | Breaking capacity and pole use change with system voltage |
| Corrente nominal | Frame rating, sensor or trip rating, setting, load, conductor and ambient conditions | The same frame can be supplied with different protection ratings |
| capacidade de interrupção | Icu e eucs at the exact project voltage | The breaker must interrupt the prospective fault safely and meet continuity needs |
| Categoria de utilização | Category A or B where applicable, short-time delay and Icw | It affects coordination strategy and short-time withstand requirements |
| Isolamento | Suitability-for-isolation marking, operating mechanism and installation requirements | Not every switching device can be assumed to provide isolation |
| Aprovações | Certificate owner, model, accessories, markings and destination market | A aprovação é confirmada pela configuração exata, não pela semelhança visual. |
ACB Applications
Define the breaker from its position in the system
The same frame current does not make two ACB applications equivalent. Source characteristics, short-time withstand, selectivity, operating sequence and service-continuity requirements must be reviewed together.
Transformer main incomer
Confirm transformer rating and impedance, secondary voltage, prospective fault current, busbar rating, short-time duty and downstream selectivity.
Bus coupler or tie breaker
Define normal and emergency bus states, allowable parallel operation, mechanical and electrical interlocking, closing logic and transfer sequence.
Generator main and transfer system
Review generator fault contribution, neutral arrangement, source compatibility, protection settings, interlocks and automatic or manual transfer controls.
Industrial process switchboard
Coordinate critical feeders, motor starting, process continuity, maintenance access, remote indication and the consequences of an upstream trip.
Critical commercial power
For data, healthcare or essential-service loads, review discrimination, redundancy, monitoring, test strategy and restoration requirements with the system designer.
OEM low-voltage switchgear
Standardize the approved breaker, cradle, trip unit, accessories, communication, drawings, labels, packaging and repeat-order reference.
ACB Quotation Checklist
Send the one-line diagram or breaker data for a faster quotation
You can begin with an existing model, panel schedule, nameplate photo or basic project information. We will identify the remaining details that need confirmation.
Describe the source and switchboard
Voltage, frequency, transformer or generator data, earthing, prospective fault current, busbar rating, design current and one-line diagram.
Define protection and operation
Frame, sensor and rated current, 3P or 4P, Icu, Ics, Icw, LI/LSI/LSIG, fixed or draw-out, settings and control voltages.
Confirme a montagem completa.
Cradle, terminals, coils, motor mechanism, contacts, interlocks, communication, drawings, quantity, destination, packaging and schedule.
ACB Accessories and Installation
Specify the breaker and its operating system together
Accessories are not generic. Mechanical fit, coil voltage, contact logic, terminal location and approval scope must match the exact ACB family.
ACB Model Verification and Bulk Supply
Crie pedidos repetidos em torno de um approved configuration
For panel builders, equipment manufacturers and distributors, a stable ACB order depends on configuration control. A frame name without its trip unit, accessories and rating data is incomplete.
Proteção relacionada contra baixa tensão
Continue o planejamento sistema de distribuição completo
Air Circuit Breaker FAQ
ACB selection questions
Utilize essas respostas para preparar as informações técnicas necessárias para a compatibilidade, substituição e aquisição de modelos.
How do I select the correct air circuit breaker?
Confirm AC or DC system voltage, source and earthing arrangement, design current, conductor capacity, frame size, rated current, poles, prospective short-circuit current, Icu, Ics, trip unit, settings, installation method, accessories, coordination and target-market requirements.
What is the difference between an ACB and an MCCB?
An ACB is commonly used at main incomers, bus couplers and high-current feeders where adjustable electronic protection, short-time withstand, selectivity and draw-out construction may be required. An MCCB is generally more compact for feeder and distribution duties. Final selection depends on verified ratings and the protection study.
Should I choose a fixed or draw-out air circuit breaker?
A fixed ACB can suit installations where compactness and lower assembly complexity are priorities. A draw-out ACB adds connected, test and disconnected positions for inspection, replacement and maintenance planning. Confirm cradle dimensions, position contacts, shutters and interlocks with the switchboard design.
What do Icu, Ics and Icw mean on an ACB?
Icu is ultimate short-circuit breaking capacity, Ics is service short-circuit breaking capacity and Icw is short-time withstand current for stated conditions. Compare each value at the actual operational voltage and required operating time.
What do LI, LSI and LSIG protection functions mean?
L is long-time overload protection, S is short-time protection, I is instantaneous protection and G is ground-fault protection where supported. The required functions and settings must follow the conductor, equipment, earthing and selectivity study.
What does utilization category B mean for an ACB?
A category B circuit breaker is designed with a rated short-time withstand current and can use an intentional short-time delay for selectivity under stated conditions. Verify the exact category, Icw, delay range and coordination data for the selected model.
Should I select a 3-pole or 4-pole ACB?
A 3-pole ACB switches the phase conductors. A 4-pole ACB also switches the neutral, while neutral protection and current rating remain model-specific. Selection depends on the earthing system, source arrangement, harmonics and project rules.
What are the connected, test and disconnected positions?
On a compatible draw-out ACB, the connected position joins main and auxiliary circuits, the test position normally allows control-circuit testing while main circuits remain isolated, and the disconnected position separates the breaker from the primary system. Exact behavior and interlocking are product-specific.
How often should an air circuit breaker be inspected or tested?
There is no single interval for every installation. Follow the exact manufacturer's instructions, site maintenance policy, operating duty, environmental conditions, fault events and local requirements. Inspection, isolation and testing must be performed by qualified personnel.
What information is needed to replace an existing ACB?
Send the full breaker and trip-unit codes, nameplate and clear photos, fixed or draw-out construction, cradle details, frame and sensor ratings, poles, voltage, Icu, Ics, Icw, settings, busbar terminals, dimensions, control voltages, accessories, communication and required quantity.
Can SENTOP support OEM and bulk ACB orders?
Eligible ACB configurations can be reviewed for samples, model matching, repeat supply, labels, packaging, documentation and other OEM requirements. Feasibility, approval scope, quantity and technical impact are confirmed for the requested model and destination.
ACB Supply Support
Send your ACB model, one-line diagram or panel requirements
SENTOP can review air circuit breaker requirements for new projects, replacements, samples, OEM switchboards, distributor ranges and bulk orders.
