Section 5: Measurement options Model 6517B Electrometer Reference Manual5-6 6517B-901-01 Rev. C / August 2015Setting a voltage limitWhile in Auto V-source Ohms, the voltage limit of the V-source can only be set to a value that is>400 V. The V-source can be set to a maximum absolute value of voltage that can be sourced. Forexample, setting a value of 30 V limits the voltage output from -30 V to +30 V. The V-LIMIT option ofthe CONFigure V-SOURCE menu is used to set the V-source voltage limit and is summarized in thetable in VSource configuration (on page 5-2).1. From the CONFigure V-SOURCE menu, select V-LIMIT to display the voltage limit selections: CONTROL: Use this selection to enable (ON) or disable (OFF) the voltage limit. Whenenabled, the V-source is limited to the specified voltage limit value (see LIMIT VALUE below) LIMIT VALUE: Use this selection to set the voltage limit using the up, down, left, and rightarrow keys. Make sure to press ENTER after changing the value2. Use the EXIT key to back out of the menu structureSelecting resistive current limitSelecting the resistive current limit places a 20 M resistor in series with the HI lead of the V-source.The RESISTIVE LIMIT option of the CONFIGURE V-SOURCE menu is used to enable or disableresistive current limit, and is summarized in the table in VSource configuration (on page 5-2).1. From the CONFigure V-SOURCE menu, select RESISTIVE LIMIT to display the options (on oroff).2. To select resistive current limiting, place the cursor on the ON option and press ENTER.Conversely, to de-select resistive current limiting, place the cursor on OFF and press ENTER.3. Use the EXIT key to back out of the menu structure.Interlock and test fixturesThe voltage source should be used with a test fixture that incorporates a safety interlock switch, suchas the Keithley Instruments Model 8009 Resistivity Test Fixture. By using the interlock feature, theModel 6517B cannot source voltage when the lid of the test fixture is open or ajar.Interlock is automatically enabled when the appropriate interlock cable is connected to the Model6517B. It is important to note that V-source does not operate unless the interlock is activated. Wheninterlock is used with the Model 8009, V-source goes into standby whenever the lid of the test fixtureis open or ajar. Use the Interlock Cable as shown in General measurement procedure (on page 4-25).This cable uses an extra line to detect which resistivity measurement type is selected at the testfixture (surface or volume).Do not connect the interlock of the Model 6517B to the interlock of another instrument. Theinterlock is designed to be connected to a single-pole interlock switch of a test fixture. Ifconnecting two or more Model 6517Bs to a single test fixture, an isolated interlock switchfor each instrument is required. Connecting multiple instrument interlocks to the sameswitch could cause the safety interlock system to fail.
