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Turn off a hotplate permanently (Permanently change a variable)

Bjarne Christian Hagen

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Hi
I have a hotplate that I want to turn off permanently when it reaches 230 °C, and I need some help. I have a heat input of 285 W and a Domain Point Probe ppb1 that measure temperature.
I have tried q = 285*(ppb1<=230 [degC]) …. This works fine and turn the hotplate off at 230 °C, BUT as the hotplates cools and gets a temperature below 230 °C the hotplate turns on again.

What I need is an expression saying:
a = 1
if ppb1>230[degC]
a=0
end
q = 285*(ppb1<=230 [degC])*a

Can someone help me? Point me in the right direction?

Best regards
Bjarne

1 Reply Last Post 10.03.2015, 08:54 GMT-4
COMSOL Moderator

Hello Bjarne Christian Hagen

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Walter Frei COMSOL Employee

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Posted: 10 years ago 10.03.2015, 08:54 GMT-4
Dear Bjarne,

You will find the approach outlined here helpful:
www.comsol.com/blogs/implementing-a-thermostat-with-the-events-interface/

Best,
Dear Bjarne, You will find the approach outlined here helpful: http://www.comsol.com/blogs/implementing-a-thermostat-with-the-events-interface/ Best,

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