Reference Multimeter and 8 ½ Digit Multimeter
Functions
37
4-Wire High-Resistance Measurements
When you make very high resistance measurements (above approximately
1 MΩ) a metal screen can be wrapped around the resistor to reduce noise,
usually caused by charge injection. Connect the GUARD terminal to the screen
to intercept leakage with the screen (in parallel with the unknown resistor). The
resistor under test should not be grounded as this will make the measurement
have greater noise. See Figure 7.
adj093f.emf
Figure 7. 4-Wire High-Resistance Measurements
4-Wire Resistance Zero
For accurate resistance measurements it is essential that a correctly connected
zero source be used when you do an Input Zero operation before you make a
series of measurements. The preferred arrangement shown in Figure 8 ensures
that thermal and induced EMF effects, and bias current effects, associated with
the Product and the measurement cables are eliminated.
Two precision 4-wire short accessories are supplied. See Accessories. Fitted
over the INPUT HI, INPUT LO, SENCE HI and SENCE LO terminals these
provide a convenient means of zeroing the Product inputs at the terminals. Use
of the 4-wire short device at the Product terminals does not address potential
sources of error within measurement cables.
adj094f.emf
Figure 8. 4-Wire Resistance Zero Measurements
To Next Page
Loading...
Need help?
General
