4-Wire Remote Sensing Connections - Keithley 2657A Reference Manual

Model 2657A High Power System SourceMeter® Instrument Reference Manual
Item Description
(1) Protective earth (safety ground) for Model
2657A
(2) Interlock connection for Model 2657A
(3) Interlocked metal safety enclosure
(4) Protective earth (safety ground) for test
fixture
(5) Model HV-CA-571-3 high-voltage triaxial
female panel mount to unterminated cable
assembly
(6) Model HV-CA-554 high-voltage triaxial
cable assembly (male to male)
(7) Model 2657A High Power System
SourceMeter
SHV SHV connections only
(8) Panel-mount SHV connector
(9) Model SHV-CA-553 SHV to high-voltage
triaxial cable assembly (male to male)

4-wire remote sensing connections

When sourcing or measuring voltage in a low-impedance test circuit (see the figure below), there can
be errors associated with lead resistance. Voltage source and measure accuracy are optimized by
using 4-wire remote sense connections. When sourcing voltage, 4-wire remote sensing ensures that
the programmed voltage is delivered to the DUT. When measuring voltage, only the voltage drop
across the DUT is measured.
Use 4-wire remote sensing for the following source-measure conditions:
•
Sourcing or measuring voltage in low impedance (less than 1 kΩ) test circuits.
•
Enforcing voltage compliance limit directly at the DUT.
When sourcing voltage in remote sense, make sure the sense leads are connected to the DUT. If a
sense lead becomes disconnected, an erroneous voltage will be sensed, and the Model 2657A may
increase the output voltage to compensate. You can use contact check to verify that the sense leads
are connected. Refer to
Also refer to
and LO does not exceed a specified value without regard to the voltage that is present on the sense
leads.
You may need additional connections for redundant protective earth (safety ground) that are not
shown in the following graphic.
When using 4-wire local sensing connections, make sure to properly configure the Model 2657A
Sense mode selection
2657A-901-01 Rev. B/December 2012
®
instrument
Contact check measurements
Overvoltage protection (OVP)
(on page 2-64).
Qty Notes
1 Keithley Instruments Model CA-568-120 is a protective
earth (safety ground) cable assembly supplied with the
instrument.
1 Pin 24 (INT) and Pin 22 (5 VDC) connected to test
fixture lid switch. Keithley Instruments Model 7709-308
is a 25-pin interlock male connector and can be used for
custom connections.
1 Select a safety enclosure with an interlock that has a
normally-open (NO) switch.
1 Redundant grounds may be required for specific test
setups (for example, setups that clamp LO).
2 See schematic for connections. Make sure to follow
High-voltage triaxial cable termination
2
1
For SHV cabling, use items (8) and (9) instead of items
(5) and (6), respectively.
2 Must be acquired by customer.
2
NOTE
(on page 2-37).
(on page 2-65). OVP will ensure that voltage between HI
Section 2: General operation
(on page 2-44).
2-47