18WuD2x

734 voltage-power directional relay • voltage-sensitive bridge
ac
Input
(E rms )
C1
C2
D1
voltage quadrupler
voltage-power directional relay A relay system in
which two circuits are connected when their voltage
difference exceeds a predetermined value in
one direction, and are disconnected when the
voltage in the opposite direction exceeds a predetermined
level.
voltage quadrupler A special rectifier circuit that
supplies a direct-current output voltage of approximately
four times the peak alternatingcurrent
input voltage.
voltage quintupler See QUINTUPLER, 1.
voltage-range multiplier 1. A multiplier resistor
(see VOLTMETER MULTIPLIER) connected in series
with a voltmeter that has an internal multiplier,
to increase the range of the instrument.
2. For an alternating-current voltmeter, an input
amplifier used to increase the sensitivity of the instrument.
voltage rating 1. For a circuit or device, the recommended
maximum voltage that can be applied,
or the recommended working voltage, as
specified. 2. For a generator, the specified output
voltage.
voltage ratio The quotient of the voltages, E 1 /E 2 ,
at two specific points in a circuit, device, or system.
Examples: ratio of input voltage to output
voltage and ratio of primary voltage to secondary
voltage.
voltage-ratio box See VOLT BOX.
voltage reference See STANDARD CELL and
ZENER-DIODE VOLTAGE REFERENCE.
voltage-reference cell See STANDARD CELL.
voltage-reference diode A Zener diode biased
into its Zener region. The voltage drop across the
diode is comparatively constant. Under proper
conditions, it can be used for reference
purposes. Also see ZENER-DIODE VOLTAGE
REFERENCE.
voltage reflection coefficient In a reflected-wave
situation, the ratio E r /E i , where E i is the fieldstrength
voltage of the incident wave, and Er is
the field-strength voltage of the reflected wave.
D2
D3
D4
E dc = 4(1.41)E rms
C3
C4
+
+
dc
Output
(E dc )
voltage-regulated supply See CONSTANT-VOLT-
AGE SOURCE.
voltage-regulating transformer A special transformer
in which a resonant circuit and core saturation
(see SATURATED OPERATION, 1) are used
to provide a constant output voltage.
voltage regulation The stabilization of a voltage
against fluctuations in source or load.
voltage-regulation constant Symbol, K v . For a
voltage-regulated power supply, the ratio
dE L /dE i , where dE i is a change in input voltage,
and dE L is the corresponding change in load voltage.
voltage regulator A circuit or device that holds an
output voltage constant during variations in the
output load or input voltage.
voltage-regulator diode See ZENER-DIODE
VOLTAGE REGULATOR.
voltage-regulator transformer See VOLTAGE-
REGULATING TRANSFORMER.
voltage relay A relay or relay circuit that is actuated
by a discrete voltage, rather than by current
or power.
voltage-responsive device See VOLTAGE-ACTU-
ATED DEVICE.
voltage rise The normal condition in a seriesresonant
circuit, in which the voltage across the
coil or capacitor is higher than the voltage applied
to the circuit.
voltage saturation In a current-actuated device,
such as a bipolar transistor, the situation in
which an increase in current provides no increase
in voltage drop beyond a certain point (the saturation
point).
voltage-sensitive bridge A bridge having a nonlinear
element (such as a voltage-dependent resistor)
as one of the arms. Because of this element,
the bridge can be balanced (with a given set of
other arms) at only one value of applied voltage.
At lower voltages, the bridge becomes unbalanced
in one direction; at higher voltage, in the opposite
direction.
Adjustable
voltage
input
Nonlinear element (varistor,
semiconductor diode, thermistor,
tungsten-filament lamp, etc.)
Output
voltage-sensitive bridge