Problem Encountered During Measurement of Energy by a Energy Meter

As a quick fix you could stick a fixed value in the voltage column... dunno if a mill is going to really pull the voltage down much unless you have a dodgy supply...
Del
(Not my field so I reserve the right to be wrong... any how I jus a cat)

If the energy meter is not faulty, then there will always be a good chance in wrong connection and also in settings.

look into it...

As others have already mentioned, you most likely have a bad voltage connection somewhere. You're Current Transformer and Phase Transform (CT and PT) ratios are not a capricious value that one can select to fudge a measurement. They are determined by the transformer and attenuation network you are using in this setup. I highly recommend that you use an oscilloscope to measure the voltages entering the energy meter to verify that things are wired correctly and that Phase A gets Current A to measure the correct phase angle.

There is a possibility that you exceeded the input voltage capability of your instrument and damaged circuitry in the energy meter. If the voltage range for the instrument without an attenuator is ±48V and you fed it directly 480 VAC RMS then you have a dead energy meter. This type of mistake can produce exactly the symptoms you've presented.

It's likely simpler than all that.

If you have ONE clamp meter and you are clampping it around ALL THREE conductors at the same time, the values will sum to zero!

This is already answerd by the original poster: The current is measured. it is the voltage which is not measured.

What is the actual current reading and voltage? Get you volt meter and see if the recorder is seeing a voltage reading. Do you actually clamp the voltage jaws around the conductor? Why not make a direct connection?

Don't know the specific meter, but is there a DC/AC option?

If it's set on DC, then the average observed voltage in line should be zero. As someone else has suggested, probably a meter setting.

A quick look at the manual for the Nanovip meter tells me that for a balanced 3 phase measurement, one clamps the current meter to one of the conductors (let us designate that as L1), and measure voltage across the other two conductors (let us call these L2 and L3). This confuses me, but I don't know what sort of algorithm the meter is using internally to calculate watts. Anyway, there is also a switch on the front of the meter that selects either single phase or three phase- check that this switch is in the correct position.

The manual does not talk about using a Potential Transformer- their diagrams show direct connection to lines L2 and L3 with standard probes. Maybe you are using a different version of the meter than the manual I am looking at?

Clamping an ammeter around one phase is pretty standard, as is using probes on any two wires to measure voltage. I think the OP will need to supply additional details. Seems odd to use a potential transformer on something as small as a drilling machine.

I agree that most drilling machines do not draw much power. Most drilling machines do not draw a significant amount of power unless something is about to break. There are a few notable exceptions though.

But once again we know next to nothing about the drill or anything that the OP is trying to measure. I have more hope that the 7 train will be extended by this tunnel boring machine than I do that the East Side access will ever be complete. I have more hope that the East Side access will be completed before we find out what the OP is actually doing.