On Fri, 26 Jan 2001 10:44:09 +0200 Francois Robbertze writes: > Sorry this is off-topic! > > My pic is connected to a triac optocoupler(MOC3041) that drives a > bigger triac (IT615) which is rated at 600V 15Amperes. > > When I switch 2.5KW heater element on at 220Volt the triac(IT615) > with heatsink becomes very-very hot. Must I get a higer rated triac > or must I look for some other problems? > > I am sure that the pic software don't switch the triac on/off the > whole time..It switch on at a certain time and off after a 5minute > delay. > You just need a larger heatsink. The heater is drawing 11.4 amps. The triac has a voltage drop of 1.2 volts (typical of a triac at 15A, see http://www.teccor.com/thyristor/triac.pdf) . So, you're dissipating 13.68W. You can calculate temperature rise by multiplying this 13.68W times the degree C/ watt rating of your heat sink. If you're running without a heat sink, the Teccor datasheet shows you can run only about 2A with an ambient of 25C. Harold FCC Rules Online at http://hallikainen.com/FccRules Lighting control for theatre and television at http://www.dovesystems.com ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu