| Vacuum Impregnation: The process of using a vacuum to remove gaseous materials from a potting compound prior to curing.
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| Vacuum: Any pressure less than atmospheric pressure. |
| Valence: The charge on an ion based on the number of electrons transferred or shared within a specific structure.
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| Valves: Devices with passages for directing flow into alternate paths. |
| Van der Waals Force: A secondary force arising from the fluctuating dipole nature of an atom with all occupied electron shells filled.
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| Vapor : Fine separated particles floating in the air and clouding it. A substance in the gaseous state. |
| Vapor Density: The amount of mass of a vapor per unit volume of the vapor.
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| Vapor Pressure: The force per unit area exerted by a vapor in an equilibrium state with its pure solid, liquid, or solution at a given temperature. Vapor pressure is a measure of a substances propensity to evaporate. Vapor pressure increases exponentially with an increase in temperature.
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| Vapor: Vapor is the gaseous state of a material below its boiling point. |
| Varistor: A two-electrode semiconductor device having a voltage-dependent nonlinear resistance.
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| Varnish Dip: The process of dipping a transformer or coil in varnish to bind or protect materials. |
| Varnish Impregnation: A varnishing and baking process used to bind together the turns on a magnetic component and protect the component against moisture. The varnish prevents movement of the conductors.
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| VDE: Verband Deutscher Elektrotechniker. A German organization which tests equipment for public safety and emitted noise.
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| Velocity: The time rate of change of displacement; dx/dt. |
| Venturi: A short tube with a constricted throat for determining fluid pressures and velocities by measuring differential pressures generated at the throat as a fluid traverses the tube.
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| Vertical Sync That segment of a video signal responsible for indicating the end of a field of video information. The primary purpose of this sync pulse is to maintain field synchronization with the incoming video signal.
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| VHF: Very High Frequency |
| Vibration Error Band: The error recorded in output of a transducer when subjected to a given set of amplitudes and frequencies |
| Vibration Error: The maximum change in output of a transducer when a specific amplitude and range of frequencies are applied to a specific axis at room temperature.
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| Vickers Hardness Test: Standard method for measuring the hardness of metals, particularly those with extremely hard surfaces; the surface is subjected to a standard pressure for a standard length of time by means of a pyramid shaped diamond. The diagonal of the resulting indention is measured under a microscope and the Vickers Hardness value read from a conversion table. |
| Virtual image: The point(s) from which light rays converge as they emerge from a lens or mirror. The rays do not actually pass through each image point, but diverge from it. |
| Virtual Particle: A particle that exists only for an extremely brief instant in an intermediary process. Then the Heisenberg Uncertainty Principle allows an apparent violation of the conservation of energy. However, if one sees only the initial decaying particle and the final decay products, one observes that the energy is conserved. |
| Viscosity: The resistance of a fluid to flow when subjected to shear stress. |
| VOC: Volatile organic compound - any organic compound which evaporates readily to the atmosphere. |
| Volatile: Any substance that evaporates readily. |
| Volatilization: The process of transfer of a chemical from the aqueous or liquid phase to the gas phase. Solubility, molecular weight, and vapor pressure of the liquid and the nature of the gas-liquid interface affect the rate of volatilization.
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| Volt Microsecond Clamp: A circuit in the control of the pulse width modulator located in the primary which terminates the pulse when the volt microseconds applied to the primary of the transformer exceeds a predetermined value.
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| Volt Microsecond: Rate of change of voltage over a period of time expressed in volts/microseconds.
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| Volt-Ampere (VA): Measurement unit of apparent power. VA implies the product of volts rms times amps rms. Whenever a power supply output is AC (alternating current), the potential exists for the voltage and current waveforms to be out-of-phase or non-sinusiodal. In these cases, the VA product can be much larger than the real power delivered. In an extreme case, the voltage and current sine waveforms may be 90 degrees out-of-phase. The power supply providing this output is delivering no real output power but could be well over its maximum voltage or current output rating.
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| Volt: The (electrical) potential difference between two points in a circuit. The fundamental unit is derived as work per unit charge-(V = W/Q). One volt is the potential difference required to move one coulomb of charge between two points in a circuit while using one joule of energy.
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| Voltage Balance: The difference in magnitude, in percent, between differential tracking output voltages of a power supply where the voltages have equal nominal values with opposite polarities.
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| Voltage Delay: Time delay for a cell or battery to deliver the required operating voltage after it is placed under load.
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| Voltage Divider: Tapped or series resistance or impedance across a source voltage to produce multiple voltages.
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| Voltage Limiting: Bounding circuit used to set specified maximum or minimum voltage levels.
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| Voltage Monitor: A circuit or device that determines whether or not an output voltage is within some specified limits.
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| Voltage Multiplier: Rectifier circuits that produce an output voltage at a given multiple greater than input voltage, usually doubling, tripling or quadrupling.
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| Voltage Regulation: The process of holding voltage constant between selected parameters, the extent of which is expressed as a percent. |
| Voltage Source: A power source that tends to deliver constant voltage.
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| Voltage Stabilization: The use of a circuit or device to hold constant an output voltage within given limits.
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| Voltage: An electrical potential which can be measured in volts.
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| Voltaic Cell: Cell producing a potential difference by chemical action. |
| Voltmeter: An instrument used to measure voltage.
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| Volume Flow Rate: Calculated using the area of the full closed conduit and the average fluid velocity in the form, Q = V x A, to arrive at the total volume quantity of flow. Q = volumetric flowrate, V = average fluid velocity, and A = cross sectional area of the pipe.
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| Volumetric Efficiency ( Haskel gas Boost Gas is compressible. Because of the "unswept Volume" in the gas section, it is impossible "inhale" the actual displacement of the booster. This volume must expand enough to lower the pressure below supply pressure before new gas can enter the gas section. As the system (outlet) pressure increases, the "loss" of effective displacement per cycle increases, and the "volumetric efficiency" decreases. When the pressure in the unswept volume is high enough, it will take the full stroke to get down to inlet pressure and the efficiency becomes "zero". The inlet/outlet pressure ratio has reached its maximum and will not inhale or transfer gas even though it may continue to cycle. |
| Volute: A stationary, spirally shaped passage that converts velocity head to pressure. |
| VSAT: Very Small Aperture Terminals are small, software-driven earth stations, used for the reliable transmission of data, video, or voice via satellite. A VSAT network consists of a central hub (master earth station), many remote VSATs, and the satellite transponder space segment. The hub station is always larger than the remote VSATs. The VSAT equipment consists of two units: one plac ed outdoors for a line-of-sight to the satellite, and one placed indoors to interface with the user`s communications device (e.g. data terminal equipment). The outdoor unit consists of a small antenna , mount, and electronics for signal reception and transmission. The indoor unit is a small desktop b ox that contains receiver and transmitter boards and an interface to the user`s equipment. Both unit s are connected via cabling. A VSAT network can be provided through a purchase or lease arrangement with fixed transmission costs regardless of distance or number of receiving sites. VSATs have become a solution in many developing countries to extend data, voice and video communications, providing h igh quality digital links to locations where telephone services are poor or not available.
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| VSWR: Voltage Standing Wave Ratio. |
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