User`s manual

9.2 VERY LOW RESISTANCES

When measuring very low resistances, the presence of thermal electromotive forces can

reduce the accuracy of the measurement. You can eliminate their effect by reversing the

direction of the current. The real measurement will then be obtained by taking half the value

of the sum of the absolute values of the «+» and «-» readings as indicated below:

■ Take a normal measurement as described in «In general» (see preceding paragraph

«IN GENERAL») and note down the value «A» displayed. By definition, the range will

be «2000 µW » because you are making a test of very low resistance,

■ Press the invertor (see 4 p. 25) changing it from the high position (+1) to the low position

(-1) and hold it for the time required to note down the displayed value «B». This should

be preceded by the «-» sign indicating that you have reversed the measurement current.

■ Make the following calculation: lAl + lBl

■ The result of this calculation gives the precise value of the resistance tested overcoming

problems of interference voltages in the measurement circuit.

NOTE:

To benefit from all the accuracy guaranteed by the instrument, take measurements

taking care to make the current lines homogeneous in the measured zone.

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