This test was done for Electrotech Forum where a LED circuit with capacitive voltage dropper was discussed.<br /><br />It shows the importance of having correctly rated mains Capacitors (X2 rated) or at least twice the peak rating of the mains voltage (1 kV in this case)<br /><br />Mains Voltage used was 240 Volts 50 Hz<br /><br />Initially three LED's were subjected to a test.<br /><br />LED-1 was connected to four 47nF 1kV rated caps ( in parrallel ) 188nF<br />LED-2 was connected to a 0.1uF 300V rms rated capacitor<br />LED-3 was connected via a resistive voltage divider consisting of two 27 k.ohm 1 Watt resistors.<br />All LED's have a 1N4448 blocking diode in parrallel with the led.<br />Also a current limit R of 680 ohm or 1 k.ohm ( 1 W ) was used to reduce inrush current destroying the led.<br />Parrallel cap discharge R's were fitted too 270 k.ohm or higher.<br /><br />Before I had my camera ready the first Cap had exploded at 92 events. I did not expect that cap to fail so early in the test.<br /><br />LED-2 was replaced with similar LED and same type capacitor. That one failed within about 200 minutes, the cap shorted internally and remained intact but the series R burnt out, LED and diode failed.<br /><br />LED-4 was added later with a X2 rated 275 V rms cap of 0.1 uF. that worked fine.<br /><br />Current measurements are shown of the circuits in use.<br /><br />The timing intervals were 57 seconds on 3 seconds off every minute.<br /><br />The survey was done over 17000 events<br /><br />I created this video with the YouTube Video Editor (http://www.youtube.com/editor)
