The peak value of an impulse voltage of prescribed form and polarity which the equipment can withstand without failure under specified conditions of test. It measures the breaker's ability to survive transient overvoltages (such as lightning strikes or switching surges). 4. Rated Uninterrupted Current ( Iucap I sub u ) or Rated Current ( Incap I sub n
Required Network Short-Circuit Current (Isc)≤Ics≤IcuRequired Network Short-Circuit Current open paren cap I sub s c end-sub close paren is less than or equal to cap I sub c s end-sub is less than or equal to cap I sub c u end-sub
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IEC 60947-2 does more than just set safety requirements; it establishes a common technical language. It defines essential characteristics such as:
The standard IEC 60947-2 consists of several sections, including:
Applies to Molded Case Circuit Breakers (MCCBs) and Air Circuit Breakers (ACBs) used in industrial environments, factories, and heavy machinery, where higher breaking capacities are required [5.3]. Key Technical Concepts in IEC 60947-2 The peak value of an impulse voltage of
Part 2 of this series is exclusively dedicated to . The standard applies to circuit-breakers whose main contacts are intended to be connected to circuits with a rated voltage not exceeding 1,000 V AC or 1,500 V DC . It is important to note that the standard is designed for devices intended to be installed and operated by instructed or skilled persons—not the general public. This makes it the appropriate standard for industrial, commercial, and utility applications where qualified personnel are responsible for operation and maintenance.
Governs devices with integrated earth-leakage modules (CBRs).
| Change Category | Description | |----------------|-------------| | Suitability for Isolation | Explicitly stated in Clause 1 as a key requirement | | Classification System | Removed classifications based on interrupting medium, design, and isolation suitability | | Current Settings | Allows adjustment via external device connectable to the release | | Circuits with Protective Separation | Added specific requirements in Clause 8.2.3.8 | | Ground-fault Testing | Additional tests for ground-fault overcurrent releases (Annex B) | | Dielectric Testing | New provisions for dielectric properties in tripped position; allows DC voltage use | | Individual Pole Breaking | Tests under phase-to-neutral AC voltage introduced | | EMC Requirements | Significant changes in Annex J | | Circuit-breaker Class | New Class W introduced in Annex L | Rated Uninterrupted Current ( Iucap I sub u
Whether you are looking for an download, engineering a power distribution system, or selecting components for a control panel, understanding this standard is essential. What is IEC 60947-2?
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