Prober Connections; Configuring Safety Interlock Operation - Keithley 4200A-SCS Reference Manual

Section 2: Connections and configuration
Testing with more than ±20 V
Asserting the interlock allows the SMU and preamplifier terminals to become hazardous,
exposing the user to possible electrical shock that could result in personal injury or death.
SMU and preamplifier terminals should be considered hazardous even if the outputs are
programmed to be low voltage. Precautions must be taken to prevent a shock hazard by
surrounding the test device and any unprotected leads (wiring) with double insulation for
250 V, Category O.
If voltages greater than ±20 V are required for testing, follow these steps:
•
Add an interlock switch to the fixture to ensure that hazardous voltages are not present when the
exterior enclosure of the test fixture is open.
The 4200A-SCS voltage output will be higher when the exterior enclosure of the test fixture is closed.
•
Connect the exterior enclosure to COMMON or safety ground using #16 AWG wire or greater.
•
Ensure that the wiring (FORCE, GUARD, and SENSE) within the fixture does not electrically
contact the exterior enclosure.

Prober connections

Refer to the prober appendices, starting with
to enable and configure prober control for supported probers.

Configuring safety interlock operation

The next figure shows typical interlock connector wiring. Note that a normally open switch should be
used. An open interlock condition occurs when the switch is open. To connect the interlock cable, see
the "Getting started" section in the 4200A-SCS User's Manual.
The Keithley Instruments 8007 and LR:8028 test fixtures have a safety interlock connected to the
instrument lid. When the lid is closed, the interlock circuit is closed (asserted), and SMU ±200 V
ranges are enabled. Conversely, the interlock circuit is open (deasserted) when the lid is open, and
SMU ±200 V ranges are disabled.
2-20
Model 4200A-SCS Parameter Analyzer Reference Manual
Set up a Probe Station (on page F-1), for details on how
4200A-901-01 Rev. C / February 2017