GL.11
Date Code 20090730 Instruction Manual SEL-734 Meter
Glossary
Transformer Impedance—Z-Number
Transformer Impedance
The resistive and reactive parameters of a transformer looking in to the
transformer primary or secondary windings. Use industry accepted open-
circuit and short-circuit tests to determine these transformer equivalent circuit
parameters.
Transformer-Rated Meter
A watt-hour meter that requires external instrument transformer(s) to isolate
or step-down the current or voltage. Transformer-rated meters are usually
located on high-current or high-voltage services. The meter reading on a
transformer-rated meter is usually in secondary units. To convert to primary
units, the reading must be multiplied by the dial multiplier, which should be
shown on the meter faceplate.
TXD
Transmitted data.
VA, VB, VC
Measured A-phase-to-neutral, B-phase-to-neutral, and C-phase-to-neutral
voltages.
VAB, VBC, VCA
Measured or calculated phase-to-phase voltages.
Vector Power (U)
Apparent power with the addition of distortion power representing the third
dimension (k) in the power triangle. Measured in volt-amps (VA), U equals iP
+ jQ + kD, where kD is distortion power that is the result of harmonics and
noise.
Virtual
Terminal Connection
A mechanism that uses a virtual serial port to provide the equivalent functions
of a dedicated serial port and a terminal.
Volatile Storage
A storage device that cannot retain data following removal of meter power.
VT
Voltage transformer. Also referred to as a potential transformer or PT.
Warm Start
The reset of a running system without removing and restoring power.
Wye
A phase-to-neutral connection of circuit elements, particularly voltage
transformers or loads. To form a wye connection using transformers, connect
the nonpolarity side of each of three voltage transformer secondaries in
common (the neutral), and take phase to neutral voltages from each of the
remaining three leads. When properly phased, these leads represent the
A-phase-, B-phase-, and C-phase-to-neutral voltages. This connection is
frequently called “four-wire wye,” alluding to the three phase leads plus the
neutral lead.
Z-Number
That portion of the meter MID string that identifies the proper ACSELERATOR
QuickSet software meter driver version and HMI driver version when creating
or editing meter settings files.
Courtesy of NationalSwitchgear.com
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