Operating the Power System 4
Keysight 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 Keysight 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 Keysight 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
Keysight 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.
