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HV using zener diode. Sales enquiries: esales 4qd. Technical support: esupport 4qd. Buyers: buyer 4qd. Webmaster: webmaster 4qd. Skip to content Current models. Symptom If the main power line zener has been damaged, the voltage on the pot will be lower than 8. Zener diode The power supply arrangement in almost all controllers made by 4QD is designed to fail safe in the event of a fault.
If you have found this article useful please share it to help others discover it Share on Facebook Share on Twitter Share on Linkedin. There will still be some voltage drop due to internal resistance. However in some circuits the current will rise to a very high level and then the diode will burn open from high power dissipation.
A diode is reverse-biased when the positive red test lead is on the cathode and the negative black test lead is on the anode. The reverse-biased resistance of a good diode displays OL on a multimeter. The diode is bad if readings are the same in both directions. The zener normally fails SHORT circuited in reverse bias, but before it get short circuited, its terminal voltage goes up, that is it behaves like open circuit for few seconds and then goes to short circuit permanently.
So using one zener will not protect the device always. Most of the zener diodes fail due to the excess power dissipation across it. Each zener has a rated power dissipation by manufacturer when the power dissipation is greater than the rated then it fails. The power dissipation is the product of voltage drop across the zener and the current flow through it.
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