Section 2: General operation
Model 2461 Interactive SourceMeter® Instrument Reference Manual
2-98
2461-901-01 A/November 2015
High-impedance output-off state
When the high-impedance output-off state is selected and the output is turned off:
•
The measurement sense is set to 2-wire
•
The output relay opens, disconnecting the instrument as a load
Opening the relay disconnects external circuitry from the inputs and outputs of the instrument. To
prevent excessive wear on the output relay, do not use this output-off state for tests that turn the
output off and on frequently.
The high-impedance output-off state should be used when the instrument is connected to a power
source or another source-measure instrument. In some cases, it may also be appropriate for devices
such as capacitors.
When the output is turned on again, the relay has a settling time of approximately 15 ms.
When the high-impedance output-off state is selected, you cannot make measurements using 2-wire
connections.
Zero output-off state
When the zero output-off state is selected and you turn off the output:
•
The measurement sense is changed to 2-wire
•
The voltage source is selected and set to 0
•
The range is set to the presently selected range (turn off autorange)
•
If the source is voltage, the current limit is not changed
•
If the source is current, the current limit is set to the programmed source current value or to 10 %
full scale of the present current range, whichever is greater
When the zero output-off state is selected, you can use the instrument as an ammeter because it is
outputting 0 V.
The zero mode is ideal for passive devices such as resistors. In most cases, it can also be used with
energy storage devices such as capacitors and inductors. This mode will discharge capacitors under
test, and remove the charge from semiconductor junctions.
Guard output-off state
Use the guard output-off state when you are measuring a load that uses an active source.
When the guard output-off state is selected and the output is turned off, the following actions occur:
•
The measurement sense is changed to 2-wire
•
The current source is selected and set to 0 A if the source is set to current (amps); otherwise, the
output remains a voltage source when the output is turned off
•
The voltage limit is set to 10 % full scale of the present voltage range
Output-off states and inductive loads
To protect the instrument from inductive energy, you may need to install a spark gap across the HI
and LO terminals. The instrument does not have internal spark gap protection.
