Steven Mark incorrect use of clamp-on meter on 17 inch TPU

[kames]

Additional clues from the 17 inch TPU are available. Consider the switches on the lower left of the TPU. The big one is clearly a three position, double pole, double throw switch. Center position is always "off." What did SM do in the video? He clicked the large switch twice and the smaller one once.
How can one make sense of this?

Simple. He just didn?t have the right switches at the tpu assembly time and was lazy to search for another one because it didn?t make any difference. 

Kames.

[wattsup]

On the LTPU the highest amperage seen near the left center toroid was 0.64 amps and at the rear output 1.24 amps.

The minimal amps seen when he scooped around the outer rings as 0.03 amps, but  his meter was not properly set when he did this. He then fixed the settings and tested the center toroid, then the rear but he never went back over the rings with the meter properly set. Too bad.

.64 amps in one toroid times two toroids makes 1.28 amps, close enough to the output amps.

Also, everyone must have noticed the left switch also had a volume type control with three wires hooked up. Could be a simple balance control.

@EM

I also have been slacking off somewhat. The video obs just drained me and I needed a change of pace. lol
Hope JD finds that Beta copy.

[BEP]

@Folks

One thing to be aware of is that the majority of modern digital clampprobes (AC/DC w/polarized Hall Effects) have a magnetic field shunt designed clamp. The purpose is to shunt unwanted magnetic fields (those not travelling through the center and the correct axis) away from or redirected from the sensing area. This is true for the ones I use at work.

I can't be 100% sure but the one used in the video appears to be that type and design. So, I'm fairly sure any current displayed would be travelling as if he had clamped around a wire.

As an example I have measured current to an exciter of a 2 megawatt generator - under full load - and had no extra readings of the main stator on a couple of inches away. Neither could I measure current in that environment unless the clamp was around a current carrying wire.
Granted, this is a fairly good meter of Fluke origin.

[ErichTesla]

@Kames
Yes, the lazy-man corollary to Occam's razor. Maybe, but another "simple" reason for the triple position DPDT is that it was needed for the LTPU.
Perhaps Jack Durban can provide us more insight into SM's "junk box." I have seen no such switch on the other TPUs.

@wattsup
I have spent way too much time lately looking at the "left" switch, but somehow I missed the "volume control." You have a good frame number?

@BEP
Do you know about what year magnetic field shunt designed clamps became available?

@all
Do any of you recognize what make of meter SM is using in the video?

ET

[BEP]

@BEP
Do you know about what year magnetic field shunt designed clamps became available?

Sorry, recent to me was about the first time I used one. It was an attachment for my 8060A. I think it was in 83 or 84. I'm aware the military used them in the mid to late 70's but they were 7 segment LED readouts. Even in 83/84 the attachment was over a grand - if memory serves.

I doubt anyone calls them by 'shunt designed' as the shunting of magnetic fields was surely just a way to make it more accurate.