Induction oven loud buzzing

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Geoff23x

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Lake City, FL
Got stumped today. When the hot water is running and the induction cooktop is on the cooktop makes an extremely loud buzzing noise. You can hear buzzing also in the panel but its coming from the water heater circuit. The hot water heater is a booster heater located under the sink 11kw. Its not the breakers causing the buzzing. What yall think?
 
Voltage drop caused by the water heater coming on at the same time causes the induction cooktop to draw more current. Any kind of inductive device interacting with ferrous metals as an inductive cooktop does, makes noise from magnetostriction. That then is based on the magnetic field strength, which is related to current. Voltage drops, current raises, more magnetostriction, more audible noise. You can likely see it in a clamp-on ammeter if you want to test the theory.

Now, why is the voltage dropping so much? THAT might be something you can fix.
 
Jraef said:
Voltage drop caused by the water heater coming on at the same time causes the induction cooktop to draw more current. Any kind of inductive device interacting with ferrous metals as an inductive cooktop does, makes noise from magnetostriction. That then is based on the magnetic field strength, which is related to current. Voltage drops, current raises, more magnetostriction, more audible noise. You can likely see it in a clamp-on ammeter if you want to test the theory.

Now, why is the voltage dropping so much? THAT might be something you can fix.
Click to expand...

wow. Now THAT is a definitive answer.
 
I've seen an ecosmart tankless water heater make some other equipment wig out when it was running... if I had everything off and a completely silent room, I could hear the relay that controls the elements in the heater cycling on and off rapidly. I guess something like this could possibly be part of your issue.
 
wwhitney said:
Are induction cooktops constant power loads?

Cheers, Wayne
Click to expand...

I have serviced GE, Kenmore, Panasonic, Bosch, and Electrolux induction cooktops. Not sure about the Bosch and electrolux, but the models of the others I've worked on do not appear to be constant power loads.

Have seen similar buzzing problems on high current appliances (mostly heat pumps at startup). Buzzing easily eliminated by looking for where the power leads laying against a metal cabinet and simply holding the leads in one place with tie-wraps and stick on anchors -- keeps the wires from vibrating* against the cabinet. Saw one case where the vibration (buzz) wore thru the insulation of the wire and shorted.

*not magnetostriction in these cases, simply attraction of the wire to the ferrous cabinet due to 60 Hz magnetic field generated by high current, wire is 'springy[ so can 'buzz'. Strictly speaking, magnetostriction is the change in shape and size of a magnetic core due to flux changes.
 
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