question
- Thread starter ioanbz
- Start date
just the cowboy
Member
Is the 34 mA moving.
Does the 34mA move and it is just high at top end? There should be a zero and span pot on the unit to set min and max output if sensor output moves and is just out of calibration. If this is in a system that has been running the sensor is probaly bad.
Does the 34mA move and it is just high at top end? There should be a zero and span pot on the unit to set min and max output if sensor output moves and is just out of calibration. If this is in a system that has been running the sensor is probaly bad.
danw
Lifetime Supporting Member
Has the transmitter ever worked properly or are you trying to get it running the first time?
If it worked before and now outputs 34mA, then it is not regulating the loop current as it should. That's it's job, to regulate the loop current to a maximum of 20mA. If it doesn't do that, there is 99% probability that it is broken and that you need to replace it.
There is 1% probability that a ground loop has been created which adds current to the loop. That could be something like a loop wire with frayed (missing) insulation that touches an ungrounded motor with a winding touching the frame and the differing potentials puts current into the loop. Or water in a junction box, but injection molders typically do not have junction b boxes out in the weather.
The test is to substitute a 4-20mA source (calibrator) and see if the loop current is the same as the calibrator is sourcing.
If it worked before and now outputs 34mA, then it is not regulating the loop current as it should. That's it's job, to regulate the loop current to a maximum of 20mA. If it doesn't do that, there is 99% probability that it is broken and that you need to replace it.
There is 1% probability that a ground loop has been created which adds current to the loop. That could be something like a loop wire with frayed (missing) insulation that touches an ungrounded motor with a winding touching the frame and the differing potentials puts current into the loop. Or water in a junction box, but injection molders typically do not have junction b boxes out in the weather.
The test is to substitute a 4-20mA source (calibrator) and see if the loop current is the same as the calibrator is sourcing.
ndzied1
Lifetime Supporting Member
The inputs on your card can be configured for voltage or current operation. Have you set the card up properly?
If you disconnect the wires from the card and just connect them to a meter in current measurement mode, what do you read? If this reading is over 20mA then you sensor almost certainly damaged as Dan suggested.
If you disconnect the wires from the card and just connect them to a meter in current measurement mode, what do you read? If this reading is over 20mA then you sensor almost certainly damaged as Dan suggested.
shazad5444
Lifetime Supporting Member
Looks, you have voltages drop, you are not getting 24 volts (Suppose). There is no scaling between 4-34 MA.
possible is there or defective sensor
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