Harmonic
The presence of harmonic content in the line conductors of a three-phase and neutral circuit can give rise to excessive levels of load current in the neutral conductor.
Category: Electrical
Fixed Equipment
Equipment designed to be fastened to a support or other wise secured in a specific location.
Final Circuit
A circuit connected directly to current-using equipment, or to a socket-outlets or other outlet points for the connection of such equipment.
Fault
Acircuit condition in which current flows through an abnormal or unintended path. The fault current may flow from line to line (phase fault) or line to earth (earth fault).
Diversity
It is often not desirable to size each conductor in a distribution system to support the total connected load at that point in the network.Diversity is applied on the basis of the anticipated loadings that are likely to result from all loads not being connected at the same time.
Distribution board
An assembly containing protective devices associated with one or more outgoing circuits fed from an incoming circuit. In the ProDesign software,a distribution board (DB) may be single-phase or three-phase,and can contain up to 100 outgoing circuits.
Selectivity
Selectivity is achieved where,under overcurrent conditions, the protective device nearest the fault operates rather than any protective device on the supply side of it,ensuring that an overcurrent condition will be disconnected without disruption to any other circuits in the system. The term selectivity supersedes previously used term ‘discrimination’.
Device rating (In)
Circuit Protective Device rating,or ‘In’ in Amperes. If the overload setting can be adjusted, then the ‘adjusted rating’ is known as ‘Ir’.
Design current (Ib)
Design current or ‘Ib’ in Amperes.The level of current to be carried by a circuit in normal service.
Current-carrying capacity
Themaximum current which can be carried by a conductor under specified conditions (Installation method, temperature,grouping,etc.)without its steady-state temperature exceeding a specified value (for example,90 ºCfor cables with thermosetting insulation).
