2.3.5 Determining Dissipation Factor (D) of Capacitors Using Nomograph
Model 252 will measure dissipation factor up to 1.999. For D values greater than 2 the
nomograph should be used. Measure the capacitance of the unknown and record the readout
display in digits only; do not record the decimal point. With the RANGE switch left in the same
position, push the G button and note the readout display in digits only; do not record the decimal
point. Turn to Figure 2-8 for the D-Q nomograph. Use a straightedge to line up the Cp digits
recorded (left-hand scale) with the Gp digits recorded (right-hand scale). D is taken from the
right-hand side of the center scale where the straightedge crosses. For example, with a Cp digital
display of “200” and a Gp digital display of “300”, D is 2.3. Accuracy of D is primarily limited by
interpolation of the nomograph.
Dissipation factor may be determined more accurately by the formula:
Where: D = dissipation factor
Gp = parallel conductance reading in counts
Cp = parallel capacitance in counts
See Table 1-1 for accuracy of Cp and Gp measurements.
Electrolytic capacitors with high dissipation are usually unstable and the measured values may drift.
2-20
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