Instruction Manual
D102797X012
Fisher™ LC340 Line Conditioner
LC340 Line Conditioner
May 2017
This instruction manual includes installation and
maintenance information for the Fisher LC340 line
conditioner (figure 1). This line conditioner is used
with FIELDVUE
™
instruments in Safety Instrumented
Figure 1. Fisher LC340 Line Conditioner
FIELD INSTRUMENT
CONNECTIONS (FLD)
Systems (SIS) in de-energize to trip (DETT)
applications. Refer to separate manuals for additional
information on other FIELDVUE products used with the
HART COMMUNICATION
CONNECTIONS (COMM)
line conditioner, such as the FIELDVUE DVC6200 SIS
digital valve controller.
Do not install, operate, or maintain an LC340 line
conditioner without being fully trained and qualified in
valve, actuator, and accessory installation, operation,
CONTROL SYSTEM
CONNECTIONS (SYS)
and maintenance. To avoid personal injury or property
damage, it is important to carefully read, understand,
and follow all of the contents of this manual, including
all safety cautions and warnings. If you have any
questions about these instructions, contact your
Emerson sales office
proceeding.
or Local Business Partner before
W8302
Description
The LC340 line conditioner is used with HARTr communicating FIELDVUE instrumentation, such as the DVC6200 SIS
digital valve controller. The line conditioner is used when this instrumentation is configured for multi‐drop operation
and is connected to a 24 volt DC logic solver output. A 24 volt DC low‐power solenoid valve may also be powered on
the same pair of wires. Although the line conditioner may mount near the logic solver, it is part of the field system just
as the field wiring is part of the field system.
The LC340 line conditioner is a passive device that is inserted in‐line with both wires of a discrete output loop. The
purpose of the line conditioner is to boost the impedance of the logic solver output to facilitate HART communication.
The line conditioner receives a 24 volt DC signal from the logic solver, which it passes through a thermal limiter and an
inductor. The high AC impedance of the inductor “conditions” the loop to meet the impedance requirements for HART
communication. The line conditioner introduces a maximum end‐to‐end resistance of 30 ohms (2 volt drop at 66 mA)
as long as the output load current is less than 100 mA. In an over‐current condition, a thermal limiting device raises the
end‐to‐end resistance until the fault is removed.
CAUTION
The LC340 is not rated for use in the process environment. Using the LC340 in the process environment may cause the line
conditioner to malfunction, resulting in damage to the product.
www.Fisher.com
LC340 Line Conditioner
May 2017
Table 1. Specifications
Instruction Manual
D102797X012
Mounting
Mounts on standard 35 mm DIN rail with other
filtering components.
Connections
Three 2‐pin Cage‐clamp style connectors accept up
to 12 AWG wire
Power Requirements
Input Current: equal to load requirements, not to
exceed 100 mA
Input Voltage: load voltage + (30 ohms x load
current); nominally 24 volts DC
1. The line conditioner requires no power to operate; its input requirements are driven entirely by its output load requirements.
The line conditioner is normally installed near the field wiring terminals of the logic solver I/O. HART communication is
only possible between the line conditioner and the field instrument and at the line conditioner COMM terminals, but
not on the logic solver side of the line conditioner. The line conditioner is not designed or intended for use in the
process environment. Neither the line conditioner nor its outputs are approved for hazardous areas. However, a
recommended intrinsic safety (IS) barrier can be connected between the FIELDVUE instrument and the line
conditioner in intrinsically safe installations. In most cases, if an IS barrier is used, the line conditioner is not needed.
(1)
Ambient Operating Temperature
-40 to 85_C (-40 to 185_F)
Ambient Relative Humidity
5 to 95%
Electrical Classification
Per IEC 61326-1
Complies with test requirements for I/O
Signal/Control ports on equipment intended for use
in industrial environments.
Dimensions
75 mm (3 inches) long by 12.5 mm (0.5 inches) wide
by 60 mm (2.4 inches) deep
Specifications
Typical specifications for the LC340 line conditioner are shown in table 1.
Installation
Refer to figure 2 for a typical installation. The LC340 line conditioner mounts on a type 35 DIN rail. Install the line
conditioner on the DIN rail. Disconnect the wires from the logic solver output side of the interconnect blocks and
connect them to the line conditioner SYS terminals, taking care to maintain correct polarity. Disconnect the wires
from the field device side of the interconnect blocks and connect them to the line conditioner FLD terminals, taking
care to maintain correct polarity.
Shields
If using shielded wiring on both sides of the line conditioner, the shield should connect across the line conditioner. If
the line conditioner connects directly to the logic solver output and shielded loop wiring is being used, connect the
shield to system ground on the instrument side of the line conditioner.
HART Wiring Connection
The COMM terminals on the line conditioner provide a convenient means to tap into the loop wiring for HART
communication. The COMM terminals can be connected to a HART Interchange multiplexer, temporarily connected to
a Field Communicator, or left unconnected.
2
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