Hardy HI 2204LT Weight Transmitter - Manual (Page 5)

HI 2201LT/HI 2204LT
1
Overview The model HI 2204LT Loop Powered Level Weight
Transmitter and model HI 2201LT Loop Powered
Level Weight Transmitter for Hazardous Areas fur-
nish power to strain gage transducers, measure the
return voltage, and adjust the 4-20 milli amp loop cur-
rent to be proportional to the transducer signal.
The HI 2201LT is Factory Mutual approved and safe
to use in hazardous operating environments. The HI
2204LT IS NOT Factory Mutual approved and
should not be used in a hazardous environment.
The HI 2201LT/HI 2204LT can be used to transmit
any strain gage signal with a bridge resistance of more
than 88 ohms. This allows transmission of pressure,
load, weight, force and torque signals including up to
four 350 ohm, full bridge, load cells.
The HI 2201LT/HI 2204LT powers itself and the
attached strain gage transducers from the 4-20 ma
loop power. This allows sensitive strain gage signals
to be transmitted over long distances without the
expense of installing additional power to remote loca-
tions. A common, low-cost power supply can be
placed anywhere in the 4-20 ma loop.
As the power supply provides loop power, the HI
2201LT/HI 2204LT controls the current flow (4-20
ma) representing the strain gage signal and receiving
devices can be placed anywhere along the loop to
monitor current flow. Typical receiving devices
include:
• Chart Records
• Panel Meters
• Bar Graphs
• Programmable Controllers
• Computers
• Relay Set Point Modules
Most receiving devices may be characterized as a load
resistor allowing the 4-20 ma signal to cause a propor-
tional voltage drop across it. Multiple receivers may
be placed on the loop provided the loop power supply
can drive the combined loads. this can be calculated
by adding the voltage requirements of the HI 2201LT/