8 - Manual setup
Terminal selection
49
SMU4000 Series Instruction Manual
Terminal selection
CNFG >
[Source Measure Action] Manual Setup
>
[Overall] Terminals
2 and 4 wire setup
The terminal configuration determines the measurement sensing scheme.
Terminal configuration options are as follows:
·
2 wire (Default)
·
2W+Guard [2 wire plus guard]
·
4 wire
It is recommended to use 4 wire measurement when it is essential to measure the voltage
delivered to a load independent of any voltage drops in the connecting supply wires or contacts.
This is important when sourcing low voltages, sourcing high currents and in very low impedance
applications.
Contact resistance does not affect the measurement result as no significant current is flowing
through the SENSE connections when utilising 4 wire measurement.
Connections can be made from either the front or rear of the instrument.
WARNING
Only ever use either the front or rear terminals, never use both at once.
Hazardous
voltages
will appear on both sets of terminals.
Hazardous voltages will appear on both sets of terminals
.
Always make connections to the instrument with the OUTPUT off
and in the Open off state;
this is the only output state that completely isolates the external circuitry from the
instrument.
Guarding
Guarding can be used for very low current and high impedance applications where potential
unwanted leakage, stray capacitance or magnetic coupling may be a problem. It can be a way of
effectively reducing the leakage current and capacitance that can be present between the MAIN
HI and LO signals.
Use guarding for isolating impedances that you do not want to measure.
WARNING
The Guard signal (rear panel and 2 wire plus guard) is driven to the same potential as the MAIN
HI. As such, if the MAIN HI is at a hazardous voltage, the same hazardous voltage level will also
be present at the Guard.
NOTE
Specific Guard terminals only feature on the rear panel. The HI SENSE terminal can be used as a
guard through the 2 wire plus guard terminal configuration.