Any Fluke 434 veterans out there?

[toygasm4u]

Hello,
I will be traveling to a customer location on Wednesday to investigate the failure of some of our products. We strongly believe that it's power quality related; it seems that a brown-out keeps killing said product. Upon initial startup, the device has a pre-charge circuit with a varistor to control currents into the DC buss. The varistor is then bypassed upon successful pre-charge. We suspect that a brown out is killing the buss voltage while the load runs. Recovery of the brown out is then spiking the DC buss capacitors, causing a high inrush situation, and blowing input fuses. Underlying problem is that the precharge circuit won't reactive on a low voltage threshold, but we've made adjustments to the firmware to hopefully address this. Strangely though, an identical product in the same facility has survived through the death of three others. I have no doubt that it is an in house condition.

I have rented a Fluke 434, but I'm not sure which operating mode will be more beneficial. Do I let the meter record V/A/Hz for a period of hours? Or do I try to set it up for a transient capture? Or do I just go with the Monitor button, which takes a look at everything? I'm hoping to determine duration and level of a number of events on the circuit that's killing our product, and the same on the circuit that's not killing our product for comparison.

I've never used a PQ analyzer beyond the Fluke 43B, and am hoping for some insight.

 

[Skogsgurra]

It is a thermistor - isn't it?

I would use the monitor function. Simply because you would miss transients in the V/A/Hz mode and because you would miss slow voltage variations in the transient mode. If you do not know exactly what you are looking for, then it is better to be open for all possibilities.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[catserveng]

The 434 is a good tool but as it described it's a Power Quality Analyzer, it is great for real time monitoring and display and I have found it to be a very good tool. But I don't think it's a very good PQ Logger.

I carry a 435 in my truck, use it alot. But when I'm looking for the kind of problems you're describing, I usually use a Fluke 1750.

I would agree with Gunner that the Monitor function is likely your best start.

You'll need to go into the setup parameters and review them, the default parameters can be a bit wide when looking for problems like yours.

 

[PQ101]

Power quality investigation is what I do, and see these type of problems all the time. Best method is to set your PQ monitor on the motor terminal or panelboard that serves the affected load equipment.

Collecting data is all you need, plus facilty inspecting i.e. for visuals, bad-lose connections, etc. You already know only one particular unit is affected, so the problem is limited to one area. Make sure there are no voltage sags at the panel serving the load equipment. Sags, swells, transients are the killers. Another area you want to check is the equipment-system grounding. Make sure there are no multiple ground rods (on main panel and at the subpanel), and all neutral-bonding connection are tight and in compliance with NEC Article 250. Typically bad or lose connection will cause havoc in the system.

Also, if you can elaborate on actual type of problem that equipment is experiencing it would be good, and I will lead you in right direction.