Variable Resistor: A resistor connected in series with a motor which can be adjusted to vary the amount of current available and thereby alter motor speed.
Variable Torque: A multi-speed motor wound so that the horsepower varies as the square of the speed.
Vector: A quantity that has magnitude and direction. This quantity is commonly represented by a directed line segment whose length represents the magnitude and whose orientation in space represents the direction.
Ventilated Enclosure: A ventilated enclosure is provided with means to permit circulation of sufficient air to remove an excess of heat, fumes or vapors.
Viscosity: The friction in liquid particles that prevents the liquid from flowing freely. The viscosity value is a number for a specific temperature, in comparison with a known liquid.
Voltage: The force that causes a current to flow in an electrical circuit. Analogous to pressure in hydraulics, voltage is often referred to as electrical pressure.
Voltage Relay: A voltage relay operates at a predetermined value of voltage. It may be an overvoltage relay, an undervoltage relay or a combination of both.
Volts per Hertz (V/Hz): The basic measurement of proper AC motor excitation level for adjustable frequency AC drive operation.
VVI (Variable Voltage Inverter): A type of AC adjustable frequency drive that controls the voltage and frequency to the motor to produce variable speed operation. A VV. type drive controls the voltage in a section other than the output section where frequency generation takes place. The frequency control is accomplished by an output bridge circuit which switches the variable voltage to the motor at the desired frequency.
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