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2 - Querying and Clearing Output Protection
The dc source will disable its output if it detects an overvoltage or overcurrent fault condition. Other
automatic fault conditions (such as overtemperature) also will disable the output.
Query and clear the dc source overcurrent protection feature as follows:
Action
1.
On the Function keypad, press Protect. In this example, OC indicates that an
overcurrent condition has occurred. Other protection indicators are: OT
(overtemperature), OV (overvoltage), RI (remote inhibit), and FS (internal
fuse is open).
2.
On the Function keypad, press Current. This displays the present output
current limit. (10% of the maximum rating is the default current limit setting).
3.
To restore normal operation after the cause of the overcurrent condition has
been removed, press Shift, Prot Clr. The OCP annunciator then will go off.
3 - Making Front Panel Measurements
When the dc source is operating in front panel meter mode, all front panel measurements are calculated
from a total of 2048 readings taken at a 46.8 microsecond sampling rate. The unit alternates between
voltage and current measurements. Therefore, the data acquisition time for a single front panel voltage or
current measurement is about 100 milliseconds. The sample rate and number of data points are fixed, and
there are no trigger controls for front panel measurements. This fixed sampling rate and data acquisition
time combined with a built-in windowing function, reduces errors due to sampling a non-integral number
of cycles of a waveform for frequencies of 25 Hz or greater. Note that the windowing function is less
accurate when measuring output waveforms for frequencies less than 25 Hz, causing the front panel
meter to jitter.
When controlling the unit over the GPIB interface, you can vary both the sampling rate and the number
of data points in each measurement. If you are using the Agilent 66332A dc source to measure waveform
data, the GPIB interface also lets you qualify the triggers that initiate the measurements. With this
flexibility, measurement accuracy can be improved for waveforms with frequencies as low as several
Hertz. Refer to chapter 3 in the Programming Guide for more information.
Two current measurement ranges can be selected in the Input menu. A high current range is available for
measuring output currents up to the 30% higher than the maximum rating of the dc source. A low current
range is available for improved resolution when measuring output currents below 20 milliamperes. The
low current measurement range is accurate to 0.1% of the reading ±2.5 microamperes. When the current
Range is set to AUTO, the unit automatically selects the range that provides the best measurement
resolution.
NOTE:
If the front panel display indicates OVLD, the output has exceeded the measurement
capability of the instrument. If the front panel display indicates
-- -- -- -- -- -- , an GPIB measurement is in progress.
As previously mentioned, the Agilent 66332A dc source has the capability of measuring output
waveform parameters such as peak, minimum, high level, and low level as illustrated in the following
figure.
Front Panel Operation - 5
Display
OC -- -- -- --
CURR 0.2045
(2 amp unit)
43
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