Measurement Basics Introduction; Insulation Resistance Measurement; Residual Charge E Ect; Absorption Phenomena - Agilent Technologies 4349B Manual

7
Measurement Basics
Introduction
This chapter provides information to help you work more e ectively.

Insulation Resistance Measurement

Residual Charge E ect
Once a high resistance insulation material has been charged with a voltage, the material will
continue to have a residual voltage across it for a while after the charging voltage is removed.
So, when you want to measure high resistance materials after they have been charged once,
wait long enough for the residual voltage to discharge or the measurement value will be
incorrect. How long you must wait depends on the characteristics of the material, the charge
voltage level, and the voltage level to which the material must discharge to before starting the
measurement.

Absorption Phenomena

When a high insulation resistance material is charged with a voltage for a long time, the
resistance value of the material will increase. So record the time from the start of the
pre-charge to the start of the measurement when measuring and comparing samples of a
material. The pre-charge time should be consistent from sample to sample.

Voltage Coecient and Temperature Coecient

The resistance value of an insulation material is measurement voltage dependent: the
insulation resistance of most insulation materials increases, as the measurement voltage is
increased.
The resistance value of the insulation material is dependent on the ambient temperature. For
the best measurement accuracy, measure the DUT while it is in a constant temperature test
chamber.
Record the measurement voltage and the ambient temperature at which the measurement is
made.
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