Section 2: General operation
2606B System SourceMeter® Instrument Reference Manual
2-60
2606B-901-01 Rev. B / May 2018
Safety shielding and hazardous voltages
The maximum output voltage for a 2606B channel is 20 V, which is considered a nonhazardous level.
However, using multiple voltage sources in a series configuration or
(on page 2-63)
can cause test circuit voltage to exceed 42 V. For example, if a 2606B has LO driven to 100 V by a
Model 2612B, the test circuit voltage could exceed 42 V. See
(on page 6-50)
for information on using multiple System SourceMeter
®
instruments.
Use #18 AWG wire or larger for connections to safety earth ground and chassis.
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
2606B.
Guarding (shown below) should be used when test circuit impedance is >1 GΩ.
See
(on page 4-16) for details on the principles of guarding.
Noise shield
Use a noise shield (see following figure) to prevent unwanted signals from being introduced into the
test circuit. Low-level signals may benefit from effective shielding. The metal noise shield surrounds
the test circuit and should be connected to LO, as shown.
Connect the enclosure of all metal test fixtures to protective earth (safety ground). See your
specific test fixture for information. Nonconductive test fixtures must be rated to double the
maximum capability of the test equipment in the system.