| Primary application | Distribution panels, outdoor feeder cabinets, solar plants, and industrial low-voltage systems. | Medium-voltage substations, utility feeders, industrial plants, and outdoor switchgear. | Overhead distribution networks where temporary faults can be cleared and service restored automatically. | Ask for application references using the same voltage class, environmental conditions, and network configuration. |
| Typical rated voltage | Up to 1,000 V AC, depending on the product design and applicable standard. | Common distribution classes include 3.6 kV, 7.2 kV, 12 kV, 24 kV, and 40.5 kV. | Common distribution classes include 12 kV, 24 kV, and 36 kV; the exact rating depends on the network. | Confirm rated voltage, insulation level, power-frequency withstand voltage, and lightning impulse withstand voltage. |
| Rated current range | Frequently available from approximately 16 A to 1,600 A, with the exact range depending on the frame size. | Common distribution designs are available from several hundred amperes up to approximately 3,150 A. | Common network ratings are approximately 200 A to 630 A, depending on the configuration. | Check continuous-current test reports, temperature-rise limits, conductor size, and derating at high ambient temperature. |
| Short-circuit performance | Breaking-capacity classes commonly range from tens of kiloamperes to around 100 kA, depending on voltage and frame size. | Short-circuit ratings commonly range from about 16 kA to 40 kA in medium-voltage distribution applications. | Typical distribution reclosers are commonly specified around 12.5 kA to 16 kA, subject to the selected voltage class. | Compare rated short-circuit breaking current, making current, short-time withstand current, and test-duty requirements. |
| Main interruption technology | Thermal-magnetic or electronic trip unit with molded-case contacts. | Vacuum interrupter with mechanical or motor-charged operating mechanism. | Vacuum interrupter combined with protection, control, and automatic reclosing functions. | Confirm operating sequence, mechanical endurance, electrical endurance, and availability of replacement parts. |
| Relevant international standards | IEC 60947-2 is the principal standard for low-voltage circuit breakers. | IEC 62271-100 covers high-voltage AC circuit breakers; IEC 62271-1 provides common specifications. | IEC 62271-111 covers automatic circuit reclosers for alternating-current systems. | Request certificates showing the exact model, rated values, standard edition, laboratory, and test date. |
| Enclosure and ingress protection | Outdoor assemblies may use sealed cabinets with IP ratings selected for dust, rain, and access protection. | Outdoor metal or polymer enclosures are commonly designed with separate ratings for the cabinet and operating compartments. | Pole-mounted housings are designed for rain, dust, condensation, and exposure to solar radiation. | Verify IP rating under IEC 60529, door-sealing details, drainage, anti-condensation heating, and corrosion protection. |
| Outdoor environmental capability | Performance depends on ambient temperature, humidity, altitude, UV exposure, and enclosure ventilation. | Design evaluation normally includes altitude correction, condensation control, pollution level, and insulation coordination. | Must withstand weather exposure, vibration, temperature cycling, and long periods of outdoor service. | Provide site altitude, minimum and maximum temperature, humidity, pollution severity, wind, salt exposure, and seismic requirements. |
| Protection and control functions | Overload and short-circuit protection; electronic versions may add adjustable long-time, short-time, instantaneous, and ground-fault functions. | Protection may use overcurrent, earth-fault, undervoltage, shunt-trip, and remote-control accessories. | Typically supports phase and earth-fault protection, event records, communications, and programmable reclosing sequences. | Compare protection curves, relay accuracy, communication protocols, cybersecurity controls, and configuration software. |
| Factory and type-test documentation | Look for routine-test records and applicable short-circuit, temperature-rise, dielectric, and mechanical tests. | Look for type-test evidence covering dielectric, temperature rise, short-circuit, mechanical endurance, and environmental conditions. | Look for recloser-specific tests covering interruption, reclosing sequences, controller functions, and communications. | Reject generic certificates that do not identify the offered model and complete rated-value combination. |
| Best supplier-selection criteria | Verified low-voltage test data, accurate trip settings, enclosure quality, accessory compatibility, and after-sales support. | Verified medium-voltage type tests, vacuum interrupter quality, insulation coordination, operating reliability, and service capability. | Protection and control integration, field communication, battery system reliability, reclosing logic, and utility acceptance. | Use the same technical specification, inspection plan, sample-testing procedure, warranty terms, and spare-parts list for every shortlisted supplier. |