| 1 | Rated Current and Frame Size | Confirm that the breaker’s rated current and frame size suit the calculated load, ambient conditions, and required future capacity. | Commercial ACB ranges commonly include ratings from about 630 A to 6,300 A; available values depend on the product series. | A suitable rating supports reliable operation without unnecessary oversizing or inadequate capacity. |
| 2 | Rated Operational Voltage | Check the rated operational voltage (Ue), system frequency, number of poles, and earthing arrangement against the project’s electrical system. | Low-voltage ACBs are commonly specified for systems such as 400 V or 690 V AC; always confirm the exact product rating. | Voltage and system configuration affect safe application and compatibility with the installation. |
| 3 | Breaking Capacity | Compare the breaker’s rated ultimate short-circuit breaking capacity (Icu) and rated service short-circuit breaking capacity (Ics) with the prospective fault current. | Request the manufacturer’s ratings at the actual operating voltage; breaking-capacity values vary by model and voltage. | The selected breaker must be able to interrupt the fault current available at its point of installation. |
| 4 | Short-Time Withstand and Selectivity | Verify rated short-time withstand current (Icw), its stated duration, and coordination settings with upstream and downstream protective devices. | Check the time-current curves and coordination study; do not infer selectivity from current rating alone. | Proper coordination can help isolate a fault while maintaining supply to unaffected parts of the system. |
| 5 | Trip Unit and Protection Functions | Review long-time, short-time, instantaneous, and ground-fault protection functions where required, along with adjustment ranges and measurement features. | Request the trip-unit datasheet, protection-setting ranges, and relevant test or configuration instructions. | Protection settings must match the system design and applicable coordination requirements. |
| 6 | Installation Type and Enclosure Compatibility | Determine whether a fixed or draw-out construction is required, and verify dimensions, terminal arrangement, clearances, and interlocking needs. | Obtain dimensional drawings and verify compatibility with the switchboard design before ordering. | Physical fit, maintainability, and safe isolation depend on the chosen construction and panel layout. |
| 7 | Standards and Certification | Check that the offered model is designed and tested to the applicable low-voltage circuit-breaker standards and project requirements. | Ask for the relevant IEC 60947-2 and applicable GB/T 14048.2 documentation, plus certificates and test reports for the offered model. | Documentation helps demonstrate that the product has been evaluated against recognized technical requirements. |
| 8 | Accessories and Control Compatibility | Confirm required shunt releases, undervoltage releases, motor operators, auxiliary contacts, communication options, and control-voltage ratings. | Request an accessory schedule and wiring diagrams that identify the exact compatible components. | Accessory availability and compatibility affect remote operation, monitoring, and integration with the control system. |
| 9 | Quality Control and Traceability | Review production quality controls, serial-number traceability, routine inspection records, and the factory acceptance test process. | Request a sample inspection record, test checklist, and details of how the supplied unit is identified and documented. | Traceable records support incoming inspection, commissioning, and future maintenance. |
| 10 | Delivery, Warranty, and After-Sales Support | Clarify lead time, warranty terms, spare-parts availability, technical support, commissioning assistance, and response procedures. | Obtain written commercial terms, a parts list, and service contact arrangements for the project location. | Reliable support can reduce commissioning delays and help maintain equipment throughout its service life. |