Hioki 3511-50, Instruction Manual, Page: 69 / 140

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5.4 Testing High Impedance Elements
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Resin film
Metallic plate
5.4 Testing High Impedance Elements
The measured value obtained when testing a high impedance element (such
as, for example, a resistor with resistance higher than 100 k
Ω
) is sometimes
unreliable, because such an element is vulnerable to the effects of external
interference and the like. In this case, reliable testing can be performed by
the use of guarding, that is, connecting a metallic plate to the GUARD
terminal and carrying out the measurement on the metallic plate.
When testing against a metallic plate, the surface of the plate should be
covered by a film of resin or the like, in order to prevent short circuiting
together the terminals.
When the open circuit compensation is performed always execute the
guarding process because of high impedance elements testing. If not, the
compensation values do not stabilize. It is not possible to obtain the reliable
measured value.