Power Outage then Induction Hob – Problem Detecting Pans

[robsterid]

Here’s another weird one.. putting it out there in case it helps someone else..

We recently had a few power cuts. When the power came back, we found that our fancy induction hob was having problem detecting pans – aka ‘pot detection’.

For reference, our hob is the Siemens freeInduction / freeInduktion EH801KU11E iQ700 which detects up to four pots placed anywhere on the surface. This is similar to the Siemens EH875KU12E and I believe is actually manufactured by Gaggenau for which their model is CX480.

After power was restored, it would correctly detect pots, but then started to identify additional non-existent pots elsewhere, switching power relays in and out seemingly at random.

Firstly we thought it had been damaged by a power spike. It looked like the calibration was all wrong. When the engineers attended they also thought the same. Fixing it would involve very complicated activity to remove the hob, dismantle it and change a number of boards, which (even with the hob costing EUR2600+) would simply be uneconomic. :eeek:
Before finalising the conclusion that the boards had been fried by a power surge, the engineers arranged to get specialist gear shipped from Germany to 1) reflash the hob software to an updated version, and 2) recalibrate the pot detection system.

Meanwhile, I had become suspicious about the quality of the reconnected power supply. The built in clock on both integrated ovens was running very slow (potentially suggesting another power surge fault) but, weirdly, completely in synch with each other Speaking to the electricity people it turned out we were actually reconnected to a temporary generator. Reading around, it turns out that supply on the main grid is carefully managed to a 50Hz average in order to support appliances which use the mains frequency for keeping time. Clearly, on the generator it wasn’t being so accurately managed.

All of which led me (somewhat in desperation to be honest) to hope that maybe the induction pot detection system might potentially rely on interruption in circulation of alternating magnetic fields to identify the pot. Maybe inaccuracy in frequency of the generated power supply would interfere with the sensitive, factory calibration of the hob??

Sure enough, now we are connected back on the main grid – both ovens are now keeping time again perfectly and, incredibly, it seems my theory was right.. the induction hob pot detection / pan detection is now working correctly again. No flash software update needed. No recalibration. No replacement boards. No trying to lever a hugely expensive glass induction hob out from it’s flush mounting into a very expensive and (no doubt) delicate granite surface.

So the lesson is, before rushing out to repair or replace ANY faulty kitchen appliances after a power cut / power outage, always check first that you are getting a proper mains supply and are not on a generator. A temporary mains supply frequency could be your issue. It affected 3x kitchen appliances of mine.

This knowledge has saved me thousands upon thousands of pounds. I hope it helps someone else.

[robsterid]

Re: Power Outage then Induction Hob – Problem Detecting Pans

Thinking about it further, BEWARE running high-end electrical appliances – particularly induction cooking – on generated power full stop. For example if you live in the middle of nowhere, or on an island and rely on a local power generator, or perhaps if you run a commercial outlet and intend to rely on generated power in event of a power outage.

I believe that accurately managing the frequency of the supply isn’t an easy thing to do, and therefore I doubt this issue will be unique to our situation.

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