﻿ V - Glossary of Terms

# Glossary of Terms: V

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Valve Positioner
Position controller mechanically connected to a moving part of a valve or its actuator, and automatically adjusts its output pressure to the actuator to maintain a position that bears a predetermined relationship to the input signal.
Variable, Measured
Process condition (such as temperature or pressure) selected to represent state of material being made or processed.
Velocity
The rate at which the position of a moving object is changing. Velocity has two characteristics: magnitude (speed) and direction. The rate of change of displacement; dx/dt.
Volt
Unit of potential difference such that the potential difference across a conductor is 1 volt when 1 ampere of current in it dissipates 1 watt of power.
Volt Amperes (VA)
A measurement of apparent power. The product of voltage and current in a reactive circuit. V (voltage) x I (current) = VA.
Voltage (V)
The difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit. One volt (V) is the difference in potential required to move one coulomb of charge between two points in a circuit, consuming one joule of energy. In other words, one volt (V) is equal to one ampere of current (I) flowing through one ohm of resistance (R), or V = IR.
Voltage Drop (VD)
This value indicates the maximum voltage drop measured across the conducting output. Sometimes referred to as Saturation Voltage. In any solid state control that switches a load, there will be some voltage dropped across the output. This voltage drop or saturation voltage will often vary with the amount of current going through the output section and the load. It should be specified with current conditions. Units = Volts (DC) or Volts RMS (AC).
Voltage Supply Range (+VS)
Maximum ripple 10 % of VS. The supply voltage should not be higher or lower than the indicated maximum or minimum values.
Voltage-to-Frequency Converter
A device that converts an analog input voltage into a sequence of digital pulses with a frequency that is proportional to the input voltage.