4-20 mA output in IRD8800 Series Modules
IRD8800 Series Modules provide a 4-20 mA DC Output proportional to set full scale range (programmable via front panel). 4 mA corresponds to 0 of the Full Scale and 20 mA corresponds to Full Scale Vibration.
The Optically Isolated 4-20 mA output for Channel A is made available at backplane terminal 5 (+) and 6 (Ground) and the Optically Isolated 4-20 mA output for Channel B is made available at the backplane terminal 29 (+) and 30 (Ground).
Connected Load should be less than 600 Ohms max across each Channel. If connected load is more than 600 Ohms across each channel - then the 4-20 mA output may get subdued.
Contacts receiving the 4-20 mA output should be potential free
When the vibration exceeds Full Scale Range - the front of the card displays Over Range and it drops the 4-20 mA of the corresponding channel to below 2.8 mA. Similarly, when the channel has some fault in signal line - the card indicates TX FAIL and it drops the 4-20 mA of the corresponding channel to below 2.8 mA. Also, when the card is in Start-Up mode (Start-up Protection Enabled and Contacts shorted to initiate Startup), the card drops the 4-20 mA of the corresponding channel to below 2.8 mA.
In the event of less than 4 mA when there is 0 vibration - the card has a facility to adjust the 4 mA and bring it to desired level.