Keysight 34420A - Page 289

Measurement Tutorial 7
Keysight 34420A User’s Guide 285
In the power-on state of the meter, offset compensation is enabled. In some
circumstances it may be desirable to turn offset compensation off. For example if
the resistor being measured does not respond quickly to changes in current, offset
compensation will not produce an accurate measurement. Resistors with very
large inductances or resistors with large values of parallel capacitance would fall
into this category. In these cases the DELAY parameter can be increased to allow
more settling time after the current source is switched on or off, or the offset
compensation function can be turned off.
Power Dissipation Effects
When measuring resistors designed for temperature measurements (or other
resistive devices with large temperature coefficients), be aware that the meter will
dissipate some power in the device-under-test. The effects of this power
dissipation can affect the measurement accuracy.
If power dissipation is a problem, there are two actions you can take: you can
select a higher measurement range to reduce the errors to acceptable levels or
you can set the meter to the low power mode to limit the test current (see
page 82). The following table shows several examples.
Normal Low Power
Range Test Current
DUT Power
(at Full Scale)
Test Current
DUT Power
(at Full Scale)
1 W 10 mA 100 mW 10 mA 100 mW
10 W 10 mA 1 mW 10 mA 1 mW
100 W 10 mA 10 mW 1 mA 100 mW
1 kW 1 mA 1 mW 100 mA10 mW
10 kW 100 mA 100 mW10 mA1 mW
100 kW 10 mA10 mW5 mA2.5 mW
1 MW 5 mA25 mW5 mA25 mW