3x PT100 Motor Protection

danw said:

How is that useable? The sum of three resistances? I fail to see how that's useable.

Dividing the sum by 3 only gives an average resistance, and then the resistance value still needs a polynomial conversion or a look-up to convert it to temperature.

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It would catch a condition that affected all three windings, or have a tolerance so tight that is likely to cause nuisance alarms.

I complained about it, but the good old boys working for drilling companies aren't all very bright. At least the windings had some kind of monitoring. The bearing temperatures were disconnected on those.