I’ve been having an odd issue. I work in a steel manufacturing business and we have recently been installing iotawatts onto CNC machines. Installed multiple of them and I only have an issue with one. The problem is that when I view the status window, it shows no wattage for the input associated to the CT installed. It also shows a small amp usage ( < .5). However, if I view the data through the graph function, then it shows recorded values. Anyone have any ideas on what might be happening? If I can provide more information, please let me know, I wasn’t sure how deep I should describe my issue. I can also provide photos of the install and whatever else is necessary.
Thank you for any and all help!
Could you post the status display, with the “Data Logs” tab expanded as well as the inputs/outputs and statistics for the Last 10 Minutes and check the Refresh button so that it refreshes every 5 seconds.
A CNC machine is typically three-phase, so please post your inputs setup setup display as well.
Graph+ is showing about 100mW-200mW at 11:46, which is basically noise or perhaps an electronic control, definitely not a running CNC machine. The status display will not show less than 2 Watts. Assuming the machine didn’t change state between 11:46 and 11:47 they are consistent.
If the machine was actually running, there is a configuration problem. You are measuring with one 200A CT. Is this atwo-wire (no neutral) 240V, single-phase machine with no neutral? Maybe a picture of the CT as installed and the wiring to the machine would provide a better context.
I’ve learned more information about the machine. It is a universal robot welder, not a CNC machine. It is 480 - 3 phase and draws a max load of or 22.1 amps.
Here is the install of the CT. Is it a problem that the CT is loose like that? You can move it up and down along the line.
That’s part of the problem. The voltage reference would need to be a 277V transformer. But also, that cable probably contains all of the three-phase L1, L2 and L3. CTs can only be placed around one conductor. To measure three-phase, you would need to place one on each conductor and then define an IoTaWatt Output to add them together for total power.
For a machine with three wires (n neutral) you would need to put CTs on two of the wires. For four wires (with neutral) you would need to put CTs on three of the wires.
Getting a 277V reference and placing two or three CTs at the machine would be difficult, but if the equipment is installed at the panel where the cables originate, it’s easy to place them on the conductors where they connect to the breakers. Since it’s only 22 Amps, you can use three 50A CTs, not much more costly than the single 200A.
When you do it at the panel, you can also monitor as many as 3 four-wire machines or 7 three-wire machines with one IoTaWatt.
Here is a 277V/480V three phase installation with three reference transformers, one for each phase. You can get pretty accurate results with just one transformer as well.
Awesome, Im glad its not a mysterious problem. Thank you for the reference. Ill pass this along to our maintenance guys and hopefully get it working correctly.
Again, thanks a lot for the help, it would’ve taken forever to find that information on my own.