Front Panel Operation
Connecting the Calibrator to a UUT
4
4-11
whenever you are testing a UUT that has a grounded LO terminal. Remember to always
maintain only one earth ground tie point in a system.
4-17. Four-Wire versus Two-Wire Connections
Four-wire and two-wire connections refer to methods of connecting the 5520A to the
UUT to cancel out test lead resistance to assure the highest precision of the calibration
output. Figures 4-2 through 4-4 illustrate the connection configurations for resistance;
Figures 4-5 and 4-6 illustrate connection configurations for capacitance. The external
sensing capability of the four- and two-wire compensated connections provides
increased precision for resistance values below 110 kΩ and capacitance values 110 nF
and above. Part of the setting up the calibrator output for resistance and capacitance
includes selections for four-wire compensation (COMP 4-wire), two-wire compensation
(COMP 2-wire) and two-wire no compensation (COMP off). (See “Setting Resistance
Output” and “Setting Capacitance Output” later in this chapter.) Note that compensated
connections for capacitance are to compensate for lead and internal resistances, not for
lead and internal capacitances.
Four-Wire Connection The four-wire connection is typical for calibrating laboratory
measurement equipment. Increased precision is provided for resistance values below
110 kΩ. For other values, the lead resistances do not degrade the calibration and the
Calibrator changes the compensation to off (COMP off).
Two-Wire Compensation The two-wire connection is typical for calibrating precision
handheld Digital Multimeters (DMMs) with a two-wire input. Increased precision is
provided for resistance values below 110 kΩ and capacitance values 110 nF and above.
For other values, the Calibrator changes the compensation to off (COMP off).
Compensation Off Compensation off is a typical connection for calibrating handheld
analog meters or DMMs with a two-wire input. This connection is used for all values of
resistance and capacitance and is usually selected when the analog meter or DMM level
of accuracy does not require the additional precision. This is the default condition
whenever an ohms or capacitance output is made, following an output that was not ohms
or capacitance.
To Next Page
Loading...
