Tektronix Keithley 2268 Series, Справочное руководство

Страница: 53 / 253

Series 2268 850 Watt DC Power Supplies Reference Manual Local Operation
2268S-901-01 Rev. A / January 2015 51
USING UNDER VOLTAGE PROTECTION (UVP)
Important:
UVP will not be active for voltage set points that are less than 1%
of model voltage.
The UVP prevents voltage settings below a set value. The UVP lets you create a voltage
window of operation when used in conjunction with the OVP setting. The UVP range is
variable from 0 V to OVP
SET
-10%.
The UVP is a protection that becomes active after the output is enabled and a period of time
has passed to allow the output to reach its set point value before the UVP protection begins
monitoring. As with OVP if the voltage set point is determined by analog control (VAP) and
the voltage strays to within 5% of the UVP set point then UVP Safe will trigger to warn the
user that they are about to trigger the UVP alarm.
The period of time before the UVP monitoring is active after the output is enabled is
determined by the rise-time delay for the model. Since the rise time is based on a purely
resistive load the user should be aware that UVP triggering might be possible in capacitive or
rectifier loads due to the rise time being longer. In these cases it is recommended that the user
mask the UVP alarm until the rise time has elapsed and then unmask the alarm to allow UVP
protection to be enabled during operation.
Defining the UVP Set Point
To define the UVP set point:
1. Turn the power supply On.
2. Set the output to the desired voltage.
3. Turn the 9-position mode control to the PRT position. is displayed.
4. Turn the rotary Adjust/Enter control until is displayed.
5. Press the rotary Adjust/Enter control to select the UVP for setting up.
6. Set up the lower limit protection using the rotary Adjust/Enter control.
Important:
The UVP range is variable from 0 volts to OVP
SET
-10%.
7. Once the desired value has been set, press the rotary Adjust/Enter control to
commit the setting.
See “Coarse and Fine Adjustment Modes” on page 31.
The SCPI command (s) for these instructions are:
[[:]SOURce[<channel>]]:VOLTage:PROTection:UNDer[:LEVel]
OVER CURRENT PROTECTION (OCP)
The OCP alarm is a firmware alarm that is only configurable using the SCPI interface. The
OCP triggers if the output current exceeds the OCP set point. Because the OCP alarm is a
firmware based alarm it has a latency before detection of the condition can occur. The user
should be aware of this latency and take this into consideration when relying on OCP to
protect a sensitive load. The maximum period for detecting an OCP condition is 300 ms.
OCP is fixed at 110% of rated current.