Before we go into pulling the 43B to shreds, it must be said that Fluke are the first company after RPM to have their instrument put through its paces.

Take a digital multimeter - not just any multimeter, but one that does voltage, current, resistance, diodes, and capacitance - and mate this with a dual channel digital storage oscilloscope with spectrum analysis capabilities, this done in the hands of a bonsai expert, and you have the Fluke 43B.

Although we deal with the realm of measurements later, it would not go amiss to briefly cover how each of the 43's capabilities (apart from voltage, current, etc.) could be handy to the power quality investigator.

Resistance: A comparable range of 50W to 30MW full-scale, including an audible continuity tester. A test voltage of 1.5V ensures diodes don't hide a potential short.
Diodes: Testing is done at 0.5mA up to 3.5V making it fairly reliable for 'in-circuit' diode testing.
Capacitance: An impressive range of 50nF to 500µF full scale making testing of EMC capacitors through to motor start and power factor correction capacitors possible (please note that this cannot test for breakdown!).
Harmonics: To see what every one else is talking about. Current or power harmonics can be done simultaneously allowing for easy tracing of resonance.
Oscilloscope Functions: The 43B excels in this area. The power of any decent storage 'scope is the ability to be set to capture events as they happen. Although not much can be adjusted (although this can be a good thing!), one can select from transient and inrush, the latter allowing various recording periods to be selected. It also has a standard two-channel 20MHz scope function with all the usual trigger modes for the very fast events that need capturing or viewing (see here).
Transients: Based on good digital storage oscilloscope principles, the transient capture is just a breeze to use. Tested on a real-life case of tracing 150V N-E transients, yet the Neutral-Earth bond proved solid, the source of the <20µs pulses was found in less than 1 hour. The resolution, even at spikes of this speed, was so good it allows the user to apply 'signature analysis' techniques.
Inrush: Available in time spans from 1 second to 5 minutes in 6 steps, and in 7 current ranges (and I would think sensitivity) from 1A to 1000A. The voltage is not recorded during the inrush capture. Whether this is a good or bad point, I am not sure. Yet, it was the only instrument that captures the weird inrush of a microwave oven! (see here)
Screen Capture: A maximum of 20 screens can be ‘captured’. The capture places the instrument on brief hold, records all the parameters, and then continues as normal. Replay allows the screen to be displayed as when it was captured, but also allows a ‘restore’ which places all the captured parameters back into the active function for modification if required (as though one had just pressed 'Hold').
Limited Logging: A limited logging capability allowing the logging of two parameters from the screen that is active at the time. There are a few limitations, but I'm not going to emphasize them now - they really are unimportant. I mean it!

Although the software is a little 'old' looking, it runs perfectly on WinXP - this proved a good start! The comms are 100% successfully through an economical USB to Serial Converter, and also over a 20 metre comms extension cable at 19200 Baud (most modern RS232 ports don't like this).

What I found brilliant was the second channel (usually dedicated to current) was completely disabled when the BNC adapter was removed. I like this as other makes of instruments tend to show fictitious harmonics when nothing is connected (and usually confuses a user or client when viewing the screen). Lest we forget, yes, they adopt the principle of shrouded 4mm for high voltage, and BNC for low voltage (current). This fits in with my preferred 'standard' connectors.

The input impedance stays at a constant 1MW allowing tricks such as external voltage dividers to be used when the input voltage exceeds its input range. The current input is fixed at 0-5Vpk input with an input impedance fixed at 1MW. This makes it ideal for voltage divider probes and to use the current channel as a 2nd voltage channel. This opens up a huge array of "enhanced uses" such as simultaneous L-N and N-E recording on a single phase supply, and 'phasing sticks' on multi-transformer HV/LV subs.

One main thing I did not like was no ability (at the time of writing) to pop in a multiplier. Using the instrument in both domestic and HV substations on 110V metering circuits keeps one having to use mental arithmetic to get to the real voltage. At 11kV this is not too bad, but try 6.6kV or even 415V. This is missing on the current channel too when using non-Fluke current clamps with strange ratios. It really would do the instrument's reputation a lot of good if the software boffs could put in a multiplier on the 'probes' menu.

Another enhancement would have been an ability to turn off the backlighting on the screen (I found no means to be able to do this). Two immediate advantages jump out being longer battery life (yip, lighting up such screens takes quite a bit of power), and the instrument becomes less 'inviting' when doing a recording as the screen isn't advertising its location in the form of a mini lighthouse.

I would have liked a facility to see the transients as they were being captured, but realize that the processing power required to update the screen may 'distract' the instrument from the main function and miss a subsequent transient following on close behind the one it is busy displaying.

All in all, I have managed to prove the 43B's full worth as a PQ-DSO. It truly does perform well, and has done so on a good few cases. It perfectly complements a full disclosure recorder as the follow-up to a diagnostic recording (i.e. now that one knows what to look for, the 43B is used to trace the source).

Oh, I nearly forgot, all of the above was accomplished without the need to look at the manual. As is, the unit I was given was an ex demo model and the manual and other good things were missing. Sure, I could have downloaded a new copy from Fluke's website, but was never compelled to. It truly is a "fly by the seat of your trousers" instrument - more than I can say for the other instruments in the PQ bag!

"There are very few PQ issues a customer may be having that a good multimeter and well-trained tech can not locate and repair".

True! And we all know the saying about tools and bad workmen! But, no matter how well trained a tech is, a multimeter takes longer and there are just some things you cannot find with a multimeter!

I don't even take a 'normal' multimeter to site as the 43B is my multimeter. And when I want more out of the multimeter, I just select the appropriate function without having to do anything more than punch a few buttons - beats the heck out of going back to the car (or even the workshop) to get the proper tool I should have had in the first place!

Now if this has whet your appetite, do look at Fluke's website... the 43B may just be on special offer (again!).

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© 07.10.03 / 04.11.04