Current waveform in transformer of FLUKE 8846A

[Kiriakos GR]

I am again practicing at making electrical measurements due my oscilloscope and current probe.

By using my AC bench-top power meter, as reference for low current measurements, now I am testing the potentials of my oscilloscope and precision current probe.
I am using my FLUKE 8846A as DUT.
55mA this is it consumption at Display OFF mode.
PF 0.700 / 240V

What puzzling my head now, this is the shape of the captured current waveform.
In comparison to AC resistive loads (almost clean sine-wave), this screen-shot this looking as very peculiar to me.
----------------------------------------------------------------------------------------------------------
In the language of electrical engineering, this is named as core saturation.
The coupling between primary and secondary is not much affected by core saturation.
However, during saturation, the dc resistance of the primary suddenly appears in parallel.

Core saturation happens when the magnetic field in the core reaches its maximum possible density, which is what happens when the applied voltage polarity re-
mains the same for too long.
Note: Saturation has nothing to do with power delivery:
the onset of saturation depends only on the voltage waveform applied to the primary.

----------------------------------------------------------------------------------------------------------

The point is that voltage waveform this is good and clear.
And therefore, what is visualized this is core saturation phenomenon at it best. 

[Kiriakos GR]

In theory, this is of how an unloaded (open circuit) secondary (looks like).
The current waveform stays near zero until the volt-seconds limit of the primary is reached.

If there is any learning from all that, this is if FLUKE 8846A transformer input, this is set at 220V, and this operates with 240V, then this core saturation, this will be greater.
Since using 240V input at my DMM, consumption this reduced, and it transformer temperature also this reduced.     

[overvolt]

So, DCUU PM9913, this now used as test device for performance inspection, of current clamp probes, at mA quantities. 
This is a very smart idea !!

Now I got the idea, of what these two red banana plugs they serve.
   Topic: DIY Breakout Box EU Receptacle - AC Standby Power measurements 6-2025




 

[Kiriakos GR]

Now I got the idea, of what these two red banana plugs they serve.
   Topic: DIY Breakout Box EU Receptacle - AC Standby Power measurements 6-2025

AC Current by-pass, for direct connection to DMM, and or for a external wire loop for the probes at 1x or 2x or 10x. 

[Kiriakos GR]

I did run one last test today, I made one 5X coil booster.
I wanted to see the differences of probe alone 100mv/A VS 500mV/A.

Indeed, now the scope has more information to capture, but the coil booster this elevated the entire pack of measured current along power line noise.
In other words, at the level of 50mA AC, I do not need any booster. 

But with this 5X coil now, I can measure with confidence since 10mA and higher at 50Hz power line (TA189).
Before (probe alone) I could not go below 40mA at AC, while the low limit at DC this is confirmed at 10mA or higher.