Tektronix Keithley SourceMeter 2450 User Manual page 44

Model 2450 SourceMeter® Instrument User's Manual Section 5: Measuring low-resistance devices
Hazardous voltages may be present on all output and guard terminals. To prevent electrical
shock that could cause injury or death, never make or break connections to the 2450 while
the output is on.
To prevent electric shock, test connections must be configured such that the user cannot
come in contact with conductors or any device under test (DUT) that is in contact with the
conductors. It is good practice to disconnect power before connecting DUTs. Safe installation
requires proper shields, barriers, and grounding to prevent contact with conductors.
There is no internal connection between protective earth (safety ground) and the LO
terminals of the 2450. Therefore, hazardous voltages (more than 30 V ) can appear on LO
RMS
terminals. This can occur when the instrument is operating in any mode. To prevent
hazardous voltage from appearing on the LO terminals, connect the LO terminal to protective
earth (safety ground) if your application allows it. You can connect the LO terminal to the
chassis ground terminal on the front panel or the chassis ground screw terminal on the rear
panel. Note that the front-panel terminals are isolated from the rear-panel terminals.
Therefore, if you are using the front-panel terminals, ground to the front-panel LO terminal. If
using the rear-panel terminals, ground to the rear panel LO terminal. Failure to follow these
guidelines can result in injury, death, or instrument damage.
The following figure shows the schematic for the application.
Figure 21: Sourcing current and measuring resistance using a 4-wire configuration
You can use either the front-panel or the rear-panel terminals for this application. The following
figures show the physical connections for the front and rear panels. Note that you must use either the
front-panel terminals or rear-panel terminals — you cannot mix connections.
The rear-panel connections are triaxial. The front-panel connections are safety banana jacks.
2450-900-01 Rev. E / August 2019 5-3