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| TRIAC based on/off circuit showing flash problem with LED lamp |
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| getfast_kiran:
Yes I wanted to use Triac expecting it to deliver more life than the HIGH current mechanical relays. Do you think it justifies the cause. |
| capt bullshot:
--- Quote from: getfast_kiran on March 01, 2017, 06:30:21 am ---Yes I wanted to use Triac expecting it to deliver more life than the HIGH current mechanical relays. Do you think it justifies the cause. --- End quote --- Can't tell that without knowing your constraints. In general - it depends. Mechanical relays are quite often used for such purposes, if chosen correctly I'd expect a life of >= 20 years and >= 100000 switching cycles for a standard power relay. For example - the relays controlling the gas furnace and water pumps in my home heating system are switching on and off 10 ... 100 times per day and is expected to do this for more than 20 years. If handled incorrectly, the relay may fail at first turn-on. A too large inrush current can weld the relay contacts together, exceeding the max. specified load may burn the contact at turn-off. |
| Zero999:
--- Quote from: getfast_kiran on March 01, 2017, 06:30:21 am ---Yes I wanted to use Triac expecting it to deliver more life than the HIGH current mechanical relays. Do you think it justifies the cause. --- End quote --- As stated above, a TRIAC isn't guaranteed to last longer than a mechanical relay. Mechanical relays are expected to last a certain number of cycles before the contacts wear out. Semiconductor switches, such as TRIACs don't have that limitation, which makes them attractive in applications with more frequent switching than relays. Semiconductors are also more resistant to mechanical shock and vibration than mechanical switches. On the other hand, mechanical switches, such as relays, can be electrically more robust than semiconductors. They wont be destroyed by ESD and can withstand over voltage and over current for longer than semiconductors. It's also possible to build relays which work at higher temperatures and are more resistant to ionising radiation than semiconductors. |
| getfast_kiran:
Thank you both for that huge helpful info on mechanical relays. I forgot to mention the requirement of low height clearance of the circuit and space requirements. So could you guys please help with the same without the need to replace the Triac ?? |
| getfast_kiran:
--- Quote from: madires on February 28, 2017, 12:56:58 pm ---You can get snubberless TRIACs and snubberless TRIAC driver optocouplers: - http://www.st.com/content/ccc/resource/technical/document/application_note/ca/ef/9d/1e/4a/9f/47/69/CD00003865.pdf/files/CD00003865.pdf/jcr:content/translations/en.CD00003865.pdf - https://www.fairchildsemi.com/collateral/Snubberless-TRIAC-Drive-Optocouplers.pdf --- End quote --- I am using a snubberless TRIAC but the optocoupler is not snubberless will try it with a snubberless optocoupler in the future. For the time being please do help me with solution confined to snubberless TRIAC BTA16 and non snubberless optocoupler 3021. |
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