3. OPERATION
Page 49
© 2008 DH Instruments, a Fluke Company
3.8.4
<4UL> (UPPER LIMIT)
PURPOSE
To set the upper pressure limit value for a pressure range and measurement mode.
PRINCIPLE
The UPPER LIMIT function provides the user with a settable pressure limit at which an alarm
sounds.
When the limit is reached, RPM4-E-DWT’s beeper sounds intermittently as long as pressure
is above the limit.
The UPPER LIMIT function has two purposes. First, when UL is set to its default value, it serves
as a warning that the maximum pressure of the active range is about to be exceeded.
Second, UL can be set by the user to a value other than the default value to provide an alarm
that a specific pressure limit has been exceeded. This feature is often used to help protect a
system to which RPM4-E-DWT is connected. For example, it might be set just over the full
scale of a device under test (DUT) that is being calibrated. Note that using AutoRange or
AutoTest automatically sets the UL to just above the AutoRange full scale (see Sections
3.7.5, 3.7.11).
The default upper limit is 105 % of AutoRange span or 102 % of Q-RPT default (maximum)
range when AutoTest is used, whichever is lower.
OPERATION
To view or edit upper limit of the active range press
[SETUP]
,
<4UL>
.
The display is:
1. Entry field for upper limit value in active pressure unit of
measure and measurement mode.
Upper limit: Hi
10200 psi g
Edit the upper limit value as desired. The maximum upper limit is 105 % of span in an
AutoRange range or 102 % of default Q-RPT full scale, whichever is smaller. Press
[ENT]
to
return to the MAIN RUN screen with the new upper limit active. Press
[ESC]
to return to the
MAIN RUN screen with no change to the upper limit.
When the upper limit has been exceeded, the display of current pressure flashes and a beep
sounds for 3 seconds on/2 seconds off intervals. Reduce the pressure applied to
RPM4-E-DWT so that it is below the upper limit to return to normal operation.
Upper limit values are specific to each range and measurement mode.
3.8.4.1
OVER PRESSURE FUNCTION
In addition to the UL function, RPM4-E-DWT has an over pressure function.
The over pressure function executes when a Q-RPT measures a pressure that is
greater than 110% of the Q-RPT’s default span. This is 1100 psi (7.56 MPa) for
the A7M Q-RPT and 11000 psi (75.6 MPa) for the A70M Q-RPT.
The over pressure function causes the measured pressure display to flash. The
overpressure function also logs the time and date of the overpressure condition
in both user and factory logs to assist in incident diagnosis (see Section 3.9.7.5).
