PicoScope 7 Software
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Non intrusive 4-20mA loop monitoring
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Stephen.brownlees
- Newbie
- Posts: 0
- Joined: Mon May 11, 2020 10:39 am
Non intrusive 4-20mA loop monitoring
Hi, looking to monitor the demand and feedback signals (4-20mA) to a control valve in a process that can't be taken off-line. Can you suggest any accessories that would allow for acceptable resolution for this application. Current clamp with output 100mV/A is best I can find but that's 0.002mV @ 20mA...
Thanks in advance,
Stephen
Thanks in advance,
Stephen
Re: Non intrusive 4-20mA loop monitoring
What about measuring the voltage over both wires.
If you know the internal resistance of the PLC or measuring device. You can calculate the current.
It is relatieve simple to use a math channel for this.
Note: don't connect the ground clip of the scope to 1 of the wires.
Use 2 channels to measure the voltage of every wire and connect the ground clip to the -24V of the system.
Then use a math channel to subtract ch1 from ch2 and optional calculate the current from this value.
Benno
If you know the internal resistance of the PLC or measuring device. You can calculate the current.
It is relatieve simple to use a math channel for this.
Note: don't connect the ground clip of the scope to 1 of the wires.
Use 2 channels to measure the voltage of every wire and connect the ground clip to the -24V of the system.
Then use a math channel to subtract ch1 from ch2 and optional calculate the current from this value.
Benno