Tektronix Keithley 2651A Reference Manual page 83

Section 2: General operation
Safety shielding and hazardous voltages
The maximum output voltage for a Model 2651A channel is 40 V, which is considered a
nonhazardous level. However, using two Model 2651A voltage sources in a series configuration or
floating a SMU
the source-measure units (SMUs) of two Model 2651A instruments can be connected in series to
apply 80 V to a device under test (DUT) (see
on using multiple Model 2651A).
Use #18 AWG wire or larger for connections to safety earth ground and chassis.
Figure 19: Safety shield for hazardous voltage using two Model 2651A instruments
Guarding
A driven guard is always enabled and provides a buffered voltage that is at the same level as the
input/output HI voltage. The purpose of guarding is to eliminate the effects of leakage current (and
capacitance) that can exist between HI and LO. Without guarding, leakage and capacitance in the
external high-impedance test circuit could be high enough to adversely affect the performance of the
Model 2651A.
2-58
Model 2651A High Power System SourceMeter® Instrument Reference Manual
(on page 2-63) can cause test circuit voltage to exceed 42 V. In the following figure,
TSP advanced features (on page 6-61) for information
2651A-901-01 Rev. C October 2021