GL.8
SEL-734 Meter Instruction Manual Date Code 20090730
Glossary
Optical Port—RAM
Optical Port
A communications interface on a metering product that allows the transfer of
information while providing electrical isolation and metering security. The
communications medium is typically infrared light transmitted and received
through the meter cover.
OR Operator
Logical OR. A Boolean SELOGIC control equation operator that compares two
Boolean values and yields either a logical 1 if either compared Boolean value
is logical 1 or a logical 0 if both compared Boolean values are logical 0.
Parentheses Operator
Math operator. Use paired parentheses to control the execution of operations
in a SEL
OGIC control equation.
PC
Personal computer.
Peak Demand Metering
Maximum demand and a time stamp for phase currents, negative-sequence
and zero-sequence currents, and powers. The SEL-734 stores peak demand
values and the date and time these occurred to nonvolatile storage overwriting
the previously stored value if the new value is larger. Should the meter lose
control power, the meter restores the peak demand information last stored.
Phase Rotation
The sequence of voltage or current phasors in a multiphase electrical system.
In an ABC phase rotation system, the B-phase voltage lags the A-phase
voltage by 120°, and the C-phase voltage lags B-phase voltage by 120°. In an
ACB phase rotation system, the C-phase voltage lags the A-phase voltage by
120°, and the B-phase voltage lags the C-phase voltage by 120°.
Pickup Time
The time measured from the application of an input signal until the output
signal asserts. You can set the time, as in the case of a logic variable timer, or
the pickup time can be a result of the characteristics of an element algorithm.
Pinout
The definition or assignment of each electrical connection at an interface.
Typically refers to a cable, connector, or jumper.
Port Settings
Communications port settings such as Data Bits, Speed, and Stop Bits.
Positive-Sequence
A configuration of three-phase currents and voltages. The currents and
voltages have equal magnitude and a phase displacement of 120°. With
conventional rotation in the counter-clockwise direction, the positive-
sequence current and voltage maxima occur in ABC order.
Power Factor
The cosine of the angle by which phase current lags or leads phase voltage in
an ac electrical circuit. Power factor equals 1.0 for power flowing to a pure
resistive load.
PT
Potential transformer. Also referred to as a voltage transformer or VT.
PTR
Potential transformer ratio.
Qualifier Code
Specifies type of range for DNP3 objects. With the help of qualifier codes,
DNP master devices can compose the shortest, most concise messages.
R_TRIG
Rising-edge trigger. Boolean SELOGIC control equation operator that triggers
an operation upon logic detection of a rising edge.
RAM
Random Access Memory. Volatile memory where the meter stores
intermediate calculation results, Meter Word bits, and other data.
Courtesy of NationalSwitchgear.com
To Next Page
