INTRODUCTION
12
GLOSSARY OF TERMS
ACCURACY is the condition or quality of conforming exactly to a standard. The
accuracy of an instrument is the extent to which the average of many measurements made
by the instrument agrees with the true value or standard being measured. The difference
between the average and the true value is the error. When this condition is a result of the
measuring instrument, it is known as out of calibration. An instruments measuring
accuracy must be considered over the whole range of the measuring instrument. This is
often expressed as linearity.
AVERAGE VOLTAGE is the sum of the instantaneous voltages in a half cycle wave
shape divided by the number of instantaneous voltages. In a sine wave, the average
voltage is equal to .637 times the peak voltage.
EMF (electromotive force) is the energy per unit charge supplied by a source of electricity
(normally expressed in volts).
The FULL SCALE VALUE is equal to the largest value of the actuating electrical
quantity which can be indicated on the scale or, in the case of instruments having their
zero between the ends of the scale; the full scale value is the arithmetic sum of the values
of the two ends of the scale.
IMPEDANCE is the apparent resistance, expressed in ohms, offered by an alternating
current circuit to the passage of electrical energy. Since frequency is one of the factors
affecting impedance, the frequency of applied energy must be specified.
INDUCTANCE is the property of an electric circuit by which a varying current induces
an emf in that circuit or a neighboring circuit.
L = a²n²/(9a + 10b)
a = coil radius in inches
b = coil length in inches
n = number of turns
LOADED TEST(ing) VOLTAGE is the actual testing voltage developed across the load
(product under test). This voltage will be lower than the open circuit voltage because of
the internal impedance of the H.V. transformer and any series limit resistance of the tester.
OPEN CIRCUIT VOLTAGE is the output voltage of the tester prior to the connection
of a load (product under test).
PEAK VOLTAGE is the maximum value present in a varying or alternating voltage.
This value may be either positive or negative. The peak value is equal to 1.414 (√2) times
the R.M.S. value.
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