Panametrics CTF878, Service Manual

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Chapter 1.
2 Model CTF878 Service Manual
3. he next prompt asks for the Zero Cutoff. Near “zero” flow, the CTF878 may have fluctuating readings due to
insufficient flow information. The zero cutoff causes velocity measurements less than the cutoff to be reported as
zero. To set the cutoff:
a.
Press
[ENTER]
to open the text box.
b. Use the numeric keys to enter the desired value.
c. Press [ENTER] to confirm your entry.
d. Press the [

] arrow key to enter the next prompt.
4. The next prompt asks for Velocity Averaging.
a. Press [ENTER] to open the drop-down list (from 2 to 100).
b. Use the [

] or [

] arrow keys to scroll to the desired number of velocity measurements to average
together to smooth out noise in the system.
c. Press [ENTER] to confirm your selection.
d. Press the [

] arrow key to enter the next prompt.
5. The final prompt, Errors Allowed, specifies the number of errors the meter can record before displaying an error
message. (The default is 2.)
a.
Press
[ENTER]
to open the text box.
b. Use the numeric keys to enter the desired value.
c. Press [ENTER] to confirm your entry.
You have finished entering data in the Signal Parameter window. To leave this window,
• Press the [

] key to return to the Signal Parameter tab, and the [

] arrow key to move to the other tabs. When
the desired tab is highlighted, press [
ENTER
] to view its contents.
• Or, press [F2] (Cancel) to return to Operate Mode without confirming the changes.
• Or, press [F3] (OK) to confirm the new data. The CTF878 returns to Operate Mode.
IMPORTANT: Do not change the remaining Signal Setup options:
AgcMgc
- Automatic or Manual Gain Control
CCorr Avg
- Cross Correlation Average
LP Filter
- Low Pass (Digital) Filter
They should be set up only by field service engineers.
1.1.5 Setting Error Limits
The Error Limits option enables you to set limits for the signals received from the transducers and the limits for some
outputs. When the parameter falls outside the programmed limits, an error indication appears. To enter this option,
scroll to the Error Limits entry on the Service Menu and press [ENTER] . The screen appears similar to
Figure 4 below.