How to Re-transmit and Isolate 4-20mA Signals from Remotely-Mounted 3-Wire Gas Detection Sensors – 8400957
Defining the Problem:
Signals from 3-wire remote sensors that monitor combustible and toxic gases are typically transmitted directly to the remote gas monitor or controller. However, in some cases, it’s desirable to send the signal to more than one destination. This can either be accomplished by re-transmitting the existing signal to additional locations; or by completely isolating the signal and then sending it to multiple locations.
System Requirements to Re-transmit and Isolate 4-20mA Signals from Remotely-Mounted 3-Wire Gas Detection Sensors:
A 3-wire remotely-mounted gas detection sensor, which transmits a 4-20mA signal. It’s important to note that a 3-wire loop is where the sensor and receiver share a ground connection with power; and the sensor uses a third wire to connect to power outside the current loop. You can use either a 2-wire (or 4-wire) isolator to re-transmit and isolate a loop to a single location. You can use a 2-wire (or 4-wire) splitter to re-transmit the loop to the two separate locations and maintain isolation on all three loops.
Implementing the Solution:
- Acromag’s signal isolators will take a 4-20mA field input and provide isolated 4-20mA output signals. Each channel (splitter units) operates independently and is isolated from the others to prevent interaction between channels.
- 600T Series isolators and splitters are field-adjustable; with zero and span trim pots located on the front of the units.
- TT Series isolators are factory calibrated for 4-20mA in-out.
- Re-calibration can be performed using either our windows software or the Acromag Agility™ mobile application for Android®.
- Follow the proper wiring practices as detailed in the user manual. Connect earth ground as indicated.
Click on the link below to download the How to Re-transmit and Isolate 4-20mA Signals from Remotely-Mounted 3-Wire Gas Detection Sensors application note.
Why Acromag to Re-transmit and Isolate 4-20mA Signals from Remotely-Mounted 3-Wire Gas Detection Sensors:
Gas detectors are usually installed in hazardous areas. These isolators and splitters are designed for UL/cUL Class 1 Division 2 safety rating for hazardous environments. The default configuration for these transmitters is for 4-20mA input and output; making installation simple and with up to 1500V of isolation, the protection is excellent.
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Watch the video version of this application note here.