Discrimination (selectivity) is achieved by automatic protective devices if a fault condition, occurring at any point in the installation, is cleared by the protective device located immediately upstream of the fault, while all other protective devices remain unaffected.
Discrimination is based on the principles of current levels, or time-delays, or a combination of both.
Discrimination may be total or partial:
Total discrimination: for all fault values from overload to bolted short-circuits , distribution is totally selective if only the circuit breaker immediately upstream located above the fault opens.
Partial discrimination: selectivity is partial if the above condition is not fulfilled up to the bolted short-circuit current but only up to a lower value. This value is referred to as the selectivity limit.
Standard IEC 60947-2 on industrial circuit breakers deals with coordination between a circuit-breaker and another short-circuit protection device combined in the same circuit. This protection device may be a fuse or another circuit breaker.
Selectivity by curves
elec calc™ allows users to check the selectivity of the different protections through a specific window showing the time/current curves of the selected protection devices.
In addition, the curves showing transient inrush currents associated with motor start-up or transformer magnetisation and the thermal withstand of cables can be displayed on the same window to check the adequation of the protection system.
Discover more features
Configuration and customization
- Client-server application
- Licenses and system requirements
Electrical calculation features
- One-line diagram
- HV/LV real-time calculation
- Power balance
- Short-circuit currents calculation
- Cable cross-section calculation
- Operating modes
- Discrimination (selectivity)
- Limitation and cascading (back-up)
- Multi-sources and multi-receivers
- Voltage drops
- Compensation of the reactive energy
- Earthing systems
- Electrical design software for aeronautics
- Electrical design software for automotive
- Electrical design software for shipbuilding
- Electrical design software for railway
- Electrical calculation solutions for Energy efficiency
- Electrical design for custom machines
- Electrical design software for panel builders
- P&ID design software for Oil & Gas
- P&ID design software for water treatment
- Electrical calculation software for the hospitals
- P&ID and electrical design for the pharmaceutical industry
- Electrical schematic software
- Electrical CAD software
- 3D electrical design software
- PLM system integration software
- Wire harness design software
- Piping diagrams software
- Hydraulic and pneumatic design software
- LV / MV electrical calculation software
- Electrical installations calculation within BIM
- Photovoltaic PV software
- PV installations sizing software
- Electrical Content Portal