Keithley 2657A

Section 2: General operation Model 2657A High Power System SourceMeter® Instrument Reference Manual
2-64 2657A-901-01 Rev. B/December 2012
The Model 2657A connections for the floating configuration are shown below.
Figure 22: Floating the Model 2657A SMU connections
The maximum floating (common mode) voltage for a SMU is 250 V. Exceeding this level may cause
damage to the instrument and create a shock hazard.
Using an external source to float a SMU could create a shock hazard in the test circuit. A shock
hazard exists whenever >42 V peak is present in the test circuit. Appropriately rated cables or
insulators must be provided for all connections to prevent access to live parts.
When >42 V is present, the test circuit must be insulated for the voltage used or surrounded by a
metal safety shield that is connected to a known protective earth (safety ground) and chassis ground
(see Safety shield (on page 2-55)).
DUT connection settings
Make sure to properly configure the Model 2657A sense mode for the specific DUT test connection
scheme. Use care to configure both the output-off state and overvoltage protection settings to
supplement safe operation of your test setup.
Sense mode selection
The sense mode can be set to use 2-wire local sensing connections (on page 2-45) or 4-wire remote
sensing connections (on page 2-47).
The default sense setting is 2-wire local.
DUT
LO
LO HI
10 V
External Source
HI
Model 2657A LO not
connected to chassis
ground (floating)
Model 2657A
!
SENSE
LO
HI
LO
GUARD
SENSE
HI
LO
3030 VDC
MAX.
250 V
MAX.
Safety shield
Connected to
protective earth
(safety ground)
+ –
WARNING
NOTE