Keysight Technologies N69100 Series, Руководство по эксплуатации и обслуживанию

Страница: 111 / 260

Front Panel Menu Reference SCPI Command
Select Protect\OCP
Enter a delay value. Then press Select .
By default, the delay timer will be started by an
output "Settings Change".
Check "CC Transition" to start the delay timer by
ANY output transition into CL mode.
To specify a 10 millisecond delay:
CURR:PROT:DEL 0.01
To start the delay timer by an output settings change:
CURR:PROT:DEL:STAR SCH
To start the delay timer by ANY output transition into
CL mode:
CURR:PROT:DEL:STAR CCTR
Delay considerations
Factors that influence how long the settings or load change may last include: difference between old
output value and new output value, the current limit setting, and the load capacitance in voltage
priority mode or load inductance in current priority mode. The delay required must be determined
empirically; the output programming-response time characteristics may be used as guidelines.
Also note that the time it takes the output to go into current limit (CL) varies - depending on the
magnitude of the over-current condition compared to the current limit setting. For example, if the
over-current is only slightly greater than the current limit setting, it may take several tens of
milliseconds for the output to set the CC status bit. If the over-current is significantly greater than the
current limit setting, it may only take a few hundred microseconds or less for the output to set the CL
status bit. To determine when the output will shut down, you must add the time it takes for the CL
status bit to the over-current protection delay time. If the over-current persists beyond the sum of
both time intervals, the output will shut down.
Primary/Secondary considerations
In primary/secondary operation, current sharing during fast load current transitions could lead to false
protection tripping if OCP is programmed independently on each unit. It is recommended that OCP is
only programmed for the primary unit. The primary/secondary OCP is implemented by the primary
unit's firmware polling the status of each secondary unit. Note however, that this may result in delay
timing to be off by a factor of up to 0.5 seconds.
Output Watchdog Timer
When enabled, the output watchdog timer causes the output to go into protection mode if there is no
SCPI I/O activity on the remote interfaces (USB, LAN, GPIB) within the user-specified time period. Note
that the watchdog timer function is NOT reset by activity on the front panel – the output will still shut
down after the time period has elapsed.
After the time period has expired, the output will be disabled, but the programmed output state is not
changed. The Prot bit in the status questionable register as well as the Prot indicator on the front
panel will be set. A watchdog protect can be cleared as described under Clear Output Protection.
The watchdog delay can be programmed from 1 to 3600 seconds in 1-second increments. To enable
the watchdog timer and specify a delay value, proceed as follows:
Keysight N69100 Series Operating and Service Guide 111
4 Using the DC Power System