Operating instructions

14
transmitter’s analog output to a selected upper and lower range
and can be done with or without an applied pressure. 4-20mA
configuration does not change the factory characterization curve
stored in the microprocessor. Sensor trimming requires an accu-
rate pressure input and adds additional compensation that
a
djusts the factory characterization curve to optimize transmitter
performance over a specific pressure range. 4-20mA configura-
t
ion provides the ability to readjust the 4~20mA sensor inputs
without an applied pressure. Reranging does not change the fac-
t
ory or characterization curve stored in the microprocessor.
Sensor trimming requires an accurate pressure input and adds addi-
t
ional compensation to the factory characterization curve to optimize
transmitter performance over a specific pressure range. Rerange
p
rovides ability to readjust the 4~20 mA points sensor inputs.
5.9.1 Sensor Trim:
The Sensor trim function adjusts the A/D signal conversion within
the transmitter sensor electronics and determines how it digitally
interprets any pressure changes applied to the sensor inputs. It is
highly recommended to perform a sensor trim when first commis-
sioning the transmitter on site. There are three ways to trim the
sensor: Sensor zero trim, full trim and zero adjustment. Sensor
zero trim is a one-point adjustment typically used to compensate
for the mounting position. Two point trim is a full sensor trim, in
which two accurate pressures are applied (equal to or greater than
the range values), and the output is linear. You should always
adjust the low trim value first to establish the correct offset.
5.9.2 D/A (Digital to Analog) Trim:
The D/A trim function makes minor adjustments to the analog
(4- 20mA) output scaling from the transmitter. It is recommended
to do a D/A trim on both hi (20mA) & low (4mA) values for best
results. This function corrects any minuscule offsets within the
D/A conversion of the transmitter.
6. MAINTENANCE:
6.1 Overview:
This chapter describes diagnostic and maintenance.
6.2 Safety Messages:
When the transmitter is in operation, operators should follow all
safety messages. Potential safety issues are indicated by a safety
alert symbol ( ). Refer to the following safety messages before
performing any operation proceeded by a ( ) symbol.
6.2.1 Warning:
6.3 Hardware Diagnostics:
If there is a failure despite a diagnostic message on the HHT, Table
6.1 can help troubleshoot the problem.
DANGER: Electrical shock can result in serious
injury. When installing transmitters in close proximi-
ty of high voltage sources (near power lines) the
transmitter leads can be subject to high voltages.
Avoid contact with the leads and terminals.
DANGER: Explosion can result in death or serious
injury. Do not remove the transmitter covers in
explosion-proof environments when the circuit is
powered. Both transmitter covers must be fully
engaged to meet explosion-proof requirements.
WARNING: Electrical shock can result in death or
serious injury. Only qualified personnel can config-
ure and wire the 3100 Smart Pressure Transmitter.
TABLE 8.1
SYMPTOM
POTENTIAL
SOURCE
CORRECTIVE ACTION
Transmitter
does not
Communicate
with HART
®
Communicator
Loop
Wiring
Check for a 250-550 ohm resistance
between the power supply and HHT.
Check for adequate voltage to the
transmitter (the transmitter requires
11.9-45 VDC).
Check for intermittent shorts, open cir-
cuits and multiple grounds.
High Output
Sensor
Input
Failure
Connect HHT and enter the transmitter
test mode to isolate a sensor failure.
Loop
Wiring
Check for dirty or defective terminals,
interconnecting pins or receptacles.
Power
Supply
Check the output voltage of the power
supply at the transmitter terminals. It
should be 11.9 to 45 VDC.
Electronics
Module
Connect HHT and enter the transmitter
test mode to isolate module failure.
Check the sensor limits to ensure the
calibration adjustments are within the
sensor range.
Erratic Output
Loop
Wiring
Check the output voltage of the power
supply at the transmitter terminals. It
should be 11.9 to 45 VDC.
Check for intermittent shorts, open cir-
cuits and multiple grounds.
Check for proper polarity at the signal
terminals.
Electronics
Module
Connect HHT and enter the transmitter
test mode to isolate an electronics
mode failure.
Low Output
or No Signal
Sensor
Element
Connect HHT and enter the transmitter
test mode to isolate a sensor failure.
Is the PV out of range?
Loop
Wiring
Check for adequate voltage to the
transmitter (the transmitter requires
11.9-45 VDC).
Check for intermittent shorts, open cir-
cuits and multiple grounds.
Check polarity of signal terminal.
Check the loop impedence.
Electronics
Module
Connect HHT and check the sensor
limits to ensure the calibration adjust-
ments are within the sensor range.