Advanced Measurement Technology 273A, Руководство пользователя

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Chapter 5—Operating Instructions 27
5.2.2. I Overload and E Overload
These two indicators are located between the Scan Status and Alphanumeric Displays. The I
OVERLOAD indicator lights if the cell current exceeds two times the selected Current Range.
Because it is impossible to reach currents of 2 A, this lamp cannot light when the current range is
"1 A." However, currents greater than 1 A will cause the E OVERLOAD indicator to light.
The E OVERLOAD indicator lights if the control amplifier output is at its limit (I > 1A or E >
control
100 V) and the control loop is not controlling the cell potential or current. This can happen in
either Potentiostatic or Galvanostatic operation and normally indicates either a cell-setup
problem or an extremely high resistance solution. Whenever E OVERLOAD lights, the problem
must be located and corrected before valid measurements can be made. A common cause in
potentiostatic operation is a disconnected reference electrode. Note that this can cause damage
to the working electrode if it occurs.
5.2.3. Scan Status Display
The Scan Status Display, located at the upper left of the front panel, consists of a symbolized
scan waveform divided into sections marked by LED's (light emitting diodes) that correspond to
the different stages of a scan. As a scan progresses, the LED corresponding to the scan stage in
progress lights, informing the user of the scan's status at a glance. There are seven LED's on the
Scan Status Display waveform. A brief discussion of each follows.
1. E/I 1: When a scan is initiated (START key), this indicator lights for 1/4 second to advise the
operator that the scan sequence has started. This may or may not correspond to actually
applying E/I 1 to the cell. For example, if the scan program includes a DELAY 1 interval, the
delay could be done with the cell ON or OFF. If the delay is done with the cell ON, the
lighting of the E/I 1 indicator marks the moment when E/I 1 is applied. If the delay is done
with the cell OFF, the lighting of the E/I 1 indicator means that the programmed scan
sequence has been initiated and nothing more.
2. DELAY 1: Scans typically (but not necessarily) begin with a delay interval, and the DELAY 1
indicator lights while the delay is in progress. If Delay 1 is PASS'ed, the DELAY 1 indicator
doesn't light. If the Delay 1 interval is 1/4 second or less, the indicator lights for 1/4 second.
See the description of the E/I 1 key for a discussion of the Delay Options.
3. SCAN 1: This indicator lights as soon as the scan waveform is applied and remains lighted
while it is in progress. If the scan is 1/4 second or less, the light remains on for 1/4 second. If
a STEP is applied instead of a ramp, the SCAN 1 indicator doesn't light at all.
4. E/I 2: This indicator lights for 1/4 second when the scan (or step) reaches the vertex potential
(current), E/I 2.
5. DELAY 2: This indicator lights during the Delay 2 interval. If this second delay is PASS'ed,
DELAY 2 doesn't light at all. If the delay lasts 1/4 second or less, the light remains on for 1/4
second.
6. SCAN 2: This indicator lights during the second leg of the scan. If the scan is 1/4 second or
less, the ight remains on for 1/4 second. If a STEP is applied instead of a ramp, SCAN 2
doesn't light.
7. E/I 3: This indicator lights for 1/4 second at the end of the scan, indicating that the
programmed sequence has been completed.
Note: If the entire scan is too quick to be displayed in real time by the LED's, the LED's that
correspond to the selected states light in sequence to show the operations performed. The timing
of this display sequence is not linked with that of the scan.