Functional description
R&S
®
TS-PSM4
18
User Manual 1178.2796.02 ─ 01
The relatively high current , which in the load’s switched on active state flows through
the high power channels, can be determined via a 5 mΩ shunt resistor. The voltage
drop at the shunt resistor is conducted via the R&S TS-PSM4’s matrix- or coupling
relays to the analogue bus of the R&S TS-PWA3 chassis and from there to, for exam-
ple, the R&S TS-PSAM measurement module. The measurement module’s voltmeter
ascertains the voltage. Via the rspsm4_GetCalculatedCurrent function of the IVI soft-
ware driver that is part of the R&S TS-PSM4, the current belonging to this voltage level
can be retrieved. It is calculated via correction values stored on the module. See also
the programming example later on in this document.
The current paths are coloured red in the diagram above, the lines with sense voltage
are blue and the paths over which the voltage drop on the shunt resistor is measured
are coloured green.
5.1.3.2
Current measurement with load in standby mode
If now the small amount of residual current through the load is to be determined, if the
latter is in standby mode, another version of the switching is chosen.
Small currents up to one ampere can be measured directly from the R&S TS-PSAM
module’s ammeter. If the current measurement gives a value via the high power chan-
nel’s shunt resistor that is less than or equal to 1 A, then the switching as shown in
can be used for the current measurement. With the channel 9 high power
relay opened, the entire current is conducted via matrix- and coupling relays on the
R&S TS-PWA3’s analogue bus and from there to the ampere meter of the R&S TS-
PSAM’s measurement module. These lines are coloured red.
The analogue bus lines of the R&S CompactTSVP and R&S PowerTSVP are designed
for a maximum current strength of 1 A.
R&S TS-PSM4
