Page 15
5.9 Calibration
The scale is implemented by calibrating the transmitter. Trim function
has several calibration functions. Smart transmitters operate
differently than analog transmitter. A smart transmitter uses a
microprocessor that contains information about the sensor's specific
characteristics in response to pressure and temperature for
calculating the process variable. 4-20mA configuration sets the
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 accurate
pressure input and adds additional compensation that adjusts the
factory characterization curve to optimize transmitter performance
over a specific pressure range. 4-20mA configuration provides the
ability to readjust the 4~20mA sensor inputs without an applied
pressure. Reranging does not change the factory or characterization
curve stored in the microprocessor. Sensor trimming requires an
accurate pressure input and adds additional compensation to the
factory characterization curve to optimize transmitter performance
over a specific pressure range. Rerange provides 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
commissioning 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
Chapter 6 Maintenance
6.1 Overview
This chapter describes diagnostic and maintenance.
6.2 Safety Message
When the transmitter is in operation, operators should follow all
safety messages. Potential safety issues are indicated by a warning
symbol (▲). Refer to the following safety messages before
performing any operation proceeded by a (▲) symbol.
6.2.1 Warning
Warning
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 serious injury:
• When installing transmitters in close proximity of high
voltage sources (near power lines) the transmitter
leads can be subject to high voltages.
• Avoid contact with the leads and terminals.
Warning
Electrical shock can result in death or serious injury:
• Only qualified personnel can configure and wire the
3100 Smart Pressure Transmitter.
P-3100:TEMPLATE 3/1/10 11:28 AM Page 16
