User`s guide

Operating the Power System 4
Series N6700 User’s Guide 87
Using the Protection Functions
Each output has independent protection functions. A front panel
status indicator will turn on when a protection function has been set.
Protection functions are latching, which means that they must be
cleared once they have been set. As explained under “Couple Output
Protection” you can configure the instrument so that when a
protection fault occurs on one output, ALL outputs will be turned off.
Of the following protection functions, only OV, OV-, OC, OSC, PROT,
and INH are user- programmable.
OV
Over-voltage protection is a hardware OVP whose trip level is a programmable value.
The OVP is always enabled.
OV−
Negative voltage protection is a hardware OVP. Only applies to Agilent N678xA SMU
and N6783A.
OC
Over-current protection is a programmable function that can be enabled or disabled.
When enabled, the output will be disabled when the output current teaches the current
limit setting.
OT
Over-temperature protection monitors the temperature of each output and shuts down
the output if any temperature exceeds the maximum factory-defined limits.
OSC
Oscillation protection shuts down the output if an oscillation is detected on the output.
Only applies to Agilent N678xA SMU.
PF
PF indicates that a power fail condition on the AC mains has disabled the output.
CP+
CP+ indicates that a positive power limit condition has disabled the output. This
protection function does not apply to all power modules. Refer to Appendix C for
further information.
CP− CP− indicates that a negative power limit condition has disabled the output. This
protection function does not apply to all power modules. Refer to Appendix C for
further information.
PROT
Prot indicates that the output is disabled, either because of a coupled protection signal
from another output, or because the programmed output watchdog time has expired.
INH
The Inhibit input (pin 3) on the rear panel digital connector can be programmed to act
as an external shutdown signal. Refer to Appendix B for further information.
Set the Over-Voltage Protection
The over-voltage protection function turns off the affected output if
the output voltage reaches the programmed over-voltage limit. The
OVP circuit monitors the voltage at the + and – output terminals.
However, on Agilent Models N678xA SMU and units with Option J01,
the voltage is monitored at the + and – sense terminals. This allows
for more precise over-voltage monitoring directly at the load.
Units with Option J01 have tracking OVP in addition to the standard
overvoltage protection. It lets you set an overvoltage protection limit
that is offset from the programmed voltage. The tracking OVP
threshold automatically tracks the real time programmed settings.
Option J01 is only available on models N6752A, N6754A and N6762A.