A unit of an electrical system that is
intended to carry but not utilize electric energy (i.e. switch, receptacle).
Demand Factor
For an electrical system or feeder circuit, this
is a ratio of the amount of connected load (in kV or amperes) that will be
operating at the same time to the total amount of connected load on the
circuit. An 80% demand factor, for instance, indicates that only 80% of the
connected load on a circuit will ever be operating at the same time.
Conductor capacity can be based on that amount of load.
Digital
A measuring or display methodology which
uses a discrete binary form using only zeros and one. In contrast, analog
uses continuously varying physical parameters to represent information.
Dielectric
An insulator; a term that refers to the
insulating material between the plates of a capacitor.
Direct Current (DC)
Circuit in which the flow of electrons is
in one direction only, from anode to cathode.
Distribution
Equipment
A device designed to provide electricity
to multiple connections (i.e. electrical panel).
Dropout
A discrete voltage loss. A voltage sag (complete or
partial) for a very short period of time (milliseconds) constitutes a
dropout
Dustproof
Constructed or protected so that dust will not
interfere with its successful operation.
Dust-tight
Constructed so that dust will not enter the enclosing case under
specified test conditions.
Duty (continuous)
A service requirement that demands operation at a
substantially constant load for an indefinitely long time.
Duty (intermittent)
A service requirement that demands operation for
alternate intervals of load and no load, load and rest, or load, no load,
and rest.
Duty, periodic
A type of intermittent duty in which the load
conditions regularly reoccur.
Duty, short time
A requirement of service that demands operations at a
substantially constant load for a short and definitely specified time.
Duty, varying
A requirement of service that demands operation at
loads, and for intervals of time, both of which may be subject to wide
variation
