10
PM5A2
5.
Use of “Guard” (G) Terminal
Depending on the measurement to be made, the
Guard (G)
may be used or not. During the measurements, the
equipment should be electrically grounded to avoid unsteady readings. When insulation is measured regarding
grounding, the
R
terminal is connected to earth and the condition by means of which the equipment potential
setting is fulfilled. If the measurement is performed between two parts, which are not grounded (for example,
between two phase conductors in a three-phase cable), the equipment
GUARD
terminal must be grounded. This
implies that
whenever a measurement is performed, one of the GUARD or R terminals must be grounded,
but not both of them simultaneously.
Technical Note 32, reproduced at the end of the manual, explains the usage of GUARD terminal in order to
eliminate the unwanted resistance effect over the result of measurements.
