GL.4
SEL-734 Meter Instruction Manual Date Code 20090730
Glossary
Dial Multiplier—Event History
Dial Multiplier
The value displayed on the meter register multiplied by the dial multiplier to
get kilowatt-hours. The dial multiplier is shown on the nameplate. For self-
contained meters, a dial multiplier of one or ten is most common. For
transformer-rated meters, the dial multiplier is determined at installation time
depending on the transformer ratios. This multiplier applies to both the
kilowatt-hour and demand (kW) readings.
Distortion
Power Ratio (Dx)
Distortion power is calculated as the ratio of average power to fundamental
power and is reported in a percentage. It is calculated on a per-phase or three-
phase basis as follows:
where:
Dx is the distortion power ratio for the respective phase
Px_avg is the average power for the respective phase
Px is the fundamental power for the respective phase
DMSI Period
The subinterval time of the demand meter time constant in demand metering.
DMTC Period
The time of the demand meter time constant in demand metering.
DNP (Distributed
Network Protocol)
Manufacturer-developed, hardware-independent communications protocol.
Dropout Time
The time measured from the removal of an input signal until the output signal
deasserts. You can set the time, in the case of a logic variable timer, or the
dropout time can be a result of the characteristics of an element algorithm.
DTE Devices
Data terminal equipment (computers, terminals, printers, meters, etc.).
Dumb Terminal
See ASCII terminal.
EIA-232
Electrical definition for point-to-point serial data communications interfaces,
based on the standard EIA/TIA-232. Formerly known as RS-232.
EIA-485
Electrical standard for multidrop serial data communications interfaces, based
on the standard EIA/TIA-485. Formerly known as RS-485.
Element
A combination of a voltage-sensing unit and a current-sensing unit that
provides an output proportional to the quantities measured. For example, a
Form 9 meter is a three-element meter. See also stator.
Energy Metering
Energy metering provides a look at imported power, exported power, and net
usage over time; measured in MWh (megawatt hours), MVARh (megavar
hours), or MVAh (megavolt hours).
ESD
(Electrostatic Discharge)
The sudden transfer of charge between objects at different potentials caused
by direct contact or induced by an electrostatic field.
Ethernet
A network physical and data link layer defined by IEEE 802.2 and IEEE
802.3.
Event History
A quick look at recent meter activity that includes a standard report header;
event number, date, time, type, and targets.
Dx
Px_avg
Px
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⎛⎞
100=
Courtesy of NationalSwitchgear.com
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