Superb Power Controller BTA41-600B

The Triac BTA41-600B is so powerful that, it can handle up to 41 amperes AC, which makes controlling more powered AC equipment.  So, the project described here is to control high power electrical gadgets, like heaters, motors etc.


The naming of Triac BTA41-600B is self explanatory as shown here.  Heat sink has to provided to the triac for high value of power control.  A cooling fan is to heat sink is to be provided for higher power control. Its metal tab is insulated, so no need to use mica insulation between the triac and heat sink.  

The circuit diagram for dimmer -cum- power control is shown below. For high power motors (above 2KW), 47 ohm 5W resistor has to be used, instead of 100 ohm 2W.


Basic Working Principle:

The terminals of triac (pins 1 and 2) starts conducting, when the voltage at gate (pin 3) reaches the threshold voltage.  So, the threshold voltage is controlled by the variable resistor (470K) and 10K series resistors with 0.1 micro-Farad disc capacitor.  The diac DB3 swtiches on, when its threshold voltage (controlled by the variable resistor), which appears at the gate pin of triac.  Then, the triac starts conducting for the half-cycle of sinusoidal wave of AC input.  This process continues for every half-cycle of the sine wave.

Due to delay in charging of the 0.1uF, through variable resistor, the initial voltage required for diac to start (threshold voltage) is also delayed.  So, the triac also starts conducting after some time, which reduces the power transmitted through the terminals of triac also.

The series connected 100 ohm resistor and 0.1uF capacitor works as snubber, which is required while connecting inductance load like motor, transformer etc.