There is no such thing as a free lunch!


Thread Starter

Stan Brown

I just felt that, as we are making some very basic design decisions for this project, we could all stand to be reminded that every decision is
a compromise, and carries with it it's own risks. These risks (no matter how small) need to be considered.

What drives me to talking about this? In short last night.

Heres what I mean. A UPS is a good thing, right, has lot's of benefits. Ever consider that it has risks? Well I can assure you it does. I spent all last night trying to recover from what happens when one mucks up.

Short version I have a large pile of dead hardware, 6 AB 177-IAD16 modules, 10 Foxboro power supplies, 2 Foxboro Fieldbus isolates, and a Nuclear gauge.

What happened? The UPS output stage failed in such a a way as to send out seriously asymmetrical current waveforms. The results very high voltage transients. Thus the dead hardware. Worse when we finally figured out what was roasting all this hardware, and tried to switch the UPS to bypass, it failed to do so, shutting down the entire woodyard, pulp mill, and washers.

So one more time. There is no free lunch!

Just thought you all would get a kick out of this.

Stan Brown [email protected] 843-745-3154
Charleston SC.
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