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4-20mA Output Information
Description - The CTM-530 provides wo 4-20mA outputs that allow for monitoring of the module status
and active alarm point location reading. These outputs are intended for annunciation purposes only. Module
monitoring is intended to be accomplished using the on board supplied dry contacts connected to a listed or
approved fi re detection control panel initiation deice circuit.
For Class “A” wiring confi guration the status output will also indicate which detector input is currently being
measured by the alarm point location meter. The measurement is alternated between inputs approximately
every 3 seconds with the status output indication which input is currently being read.
The output levels are detailed below.
Status Output - 4-20mA Output Loop 1:
Loop Fault - 4mA or less
Open - 6mA
Normal - 10mA
Initiating Device Circuit Out Short Fault - 13mA
Initiating Device Circuit Return Short Fault - 15mA
Initiating Device Circuit Out Alarm - 17mA
Initiating Device Circuit Return Alarm - 19mA
Note: For systems employing an isolated power source for the 4-20mA loops; Module Power Failure will
report at greater than or equal to 20mA.
Alarm Point Location Output - 4-20mA Output Loop 2:
4-20mA Full Scale corresponds to 0-8000 Feet
4mA = 0 Feet -20mA = 8000 Feet.
To calculate current to distance in feet use the following formula:
Current in mA = (I)
(I-4) / 0.002 = Distance in Feet
To convert to Meters:
Distance in Feet x 0.3048
Note: To insure status levels the total 4-20mA measurement loop resistance including feed cable, measurement device
and load resistor must not exceed the values below.
Supply Voltage @ 12VDC - Total loop resistance not to exceed 300 Ohms
Supply Voltage @ 24VDC - Total loop resistance not to exceed 800 Ohms
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