GPI GM001, Руководство пользователя, Страница: 12 / 20

12
Changing Response Time
The 4-20 mA with Display comes from the factory with a
default 0.7 seconds response time.
If you reset the response time (procedure detailed be-
low) you MUST then reset the 4-20 mA endpoints.
To give good performance with a variety of sensor types,
many frequency-to-analog converters, including the GPI
4-20 mA Out with Display, offer two or more settings for
“response time” (sometimes referred to as “settling time” or
“averaging time”).
• Longer (slower) response times are needed for sensor
types that generate very low frequency outputs (like
GM Series oval gear flowmeters).
• Operating a meter at high flowrates may require a
shorter (faster) response time to achieve the best
transmitter performance.
• Shorter (faster) response times are preferable for sen-
sors that generate higher frequency outputs (GPI turbine
meters, for example).
• Longer (slower) response times are also appropriate in
situations where sensor-output frequency fluctuates or
wobbles substantially.
The GPI 4-20 mA Out with Display offers a choice of five re-
sponse-time settings, selectable by the unit’s pushbuttons.
Procedure
1. Start with the unit unpowered. If the unit is presently
operating, temporarily disable its external power supply.
Be sure to allow at least 30 seconds to elapse with unit
unpowered.
2. Press and hold the “4” button. While holding, watch
the indicator light and power up the 4-20 mA Out with
Display.
3. Shortly after power is applied, the light will blink one or
more times. Count the number of blinks (from 1 to 5 blinks)
and release the button after the blinking has finished.
NOTE: If necessary, repeat steps 1 through 3 to get the
number of blinks corresponding to the response time
you want.
Blinks Response Time
1 blink 0.3 second
2 blinks 0.7 second
3 blinks 1.3 second
4 blinks 2.6 second
5 blinks 5.2 second
In normal operation, the 4-20 mA Out with Display always av-
erages two sequential input readings. The time delay from an
abrupt change in input frequency to a final, stabilized output
reading is always twice that shown in the above table.
MAINTENANCE
Check cable-entry seals periodically. Tighten and/or apply
sealant if needed. This is especially important in environ-
ments containing heavy concentrations of dust, oil mist, or
other residue.
Check all wiring connections occasionally for oxidation or
corrosion. Clean and re-seat if such conditions are noted.
If necessary, check and re-seat any connections that may
have been subjected to strain (during rework or construction,
for example).
WARNING