Model 2657A-PM-200 Protection Module
PA-1055 Rev. A / February 2012
17
Verify voltage protection device between Guard and Force LO
A Keithley SourceMeter
instrument capable of sourcing 20 mA at 300 V is required for verfication procedures E
and F. The Model 2657A High Power System SourceMeter
Instrument or Model 2410 High Voltage
SourceMeter
Instrument is recommended. An oscilloscope capable of measuring up to 300 V is also
recommended.
A safety shield must be used whenever hazardous voltages (>30 V RMS, 42 V peak) will be
present in the test circuit. To prevent electrical shock that could cause injury or death, never
use a Keithley SourceMeter
®
instrument in a test circuit that may contain hazardous voltages
without a properly installed and configured safety shield. The following procedures show the
use of a metal safety shield. Connect the enclosure of the metal test fixture to protective earth
(safety ground).
If using a nonconductive test fixture, it must be rated to double the maximum capability of the
test equipment in the system and the two green-yellow ground cables for the Model 2657A-
PM-200 must be connected to protective earth (safety ground). Failure to attach the ground
wires to a known protective earth may result in electric shock.
Not shown in the simplified block diagram are redundant voltage protection devices between the inner shields
(guard) of the HI and SH (sense HI) terminals of the Model 2657A-PM-200. Verification procedures E and F checks
both of these devices.
Verification procedure E
Verify proper operation of the protection device between the inner shields of the Sense HI (SH) and LO terminals of
the Model 2657A-PM-200:
1. As shown in the connection drawing below, connect the high voltage source-measure unit (HV SMU) to the SH
and SL triaxial connectors of the protection module:
a. Connect the SMU Force HI terminal to the inner shield of the SH OUT triaxial connector of the Model
2657A-PM-200.
b. Connect the SMU Force LO terminal to the inner shield of the SL OUT triaxial connector of the Model
2657A-PM-200.
