T
treez
Guest
Hello
We were measuring the temperature of the tab of a TO220 FET (dissipating 3W) in an 60W offline flyback SMPS.
We glued the the k type thermocouple end to a small piece of kapton tape which was covering a small bit of the tab. However, the high dv/dt switching voltage coupled through to the thermocouple and afflicted the reading. Therefore we solved the problem by using 2 layers of kapton tape instead of one.
We would like to know how far off our temperature measurement of the tab is? …. given that there are 2 layers of kapton tape between tab and thermocouple
We know the formula for heat transfer….
Q/t = k.A.[delta(T)] /d
Where:-
A = 6 e-6
K = 0.12
Q/t is a variable which we cant find
Delta(T) is what we want.
We were measuring the temperature of the tab of a TO220 FET (dissipating 3W) in an 60W offline flyback SMPS.
We glued the the k type thermocouple end to a small piece of kapton tape which was covering a small bit of the tab. However, the high dv/dt switching voltage coupled through to the thermocouple and afflicted the reading. Therefore we solved the problem by using 2 layers of kapton tape instead of one.
We would like to know how far off our temperature measurement of the tab is? …. given that there are 2 layers of kapton tape between tab and thermocouple
We know the formula for heat transfer….
Q/t = k.A.[delta(T)] /d
Where:-
A = 6 e-6
K = 0.12
Q/t is a variable which we cant find
Delta(T) is what we want.