Electronics > Beginners
power input for small transformer, good practice
Karlo_Moharic:
In case of HV surge , easily blows up , sending glass everywhere and damaging nearby components
ejeffrey:
--- Quote from: exe on June 27, 2018, 08:52:41 am ---I'd put a fuse :). Also EMI filter of lowest current rating possible as those have bigger inductance and, presumably, filter better. They also come at least in two flavors: normal and medical. I don't remember the difference, but you can google it.
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Medical has less or no capacitance to ground (class Y capacitors). This increases EMI or requires a more complicated filter to reach the same EMI suppression. The tradeoff is that it has less leakage to chassis/signal ground. Low leakage current is good when you are powering something with electrodes that might be attached to someone or even inserted into someone.
ejeffrey:
--- Quote from: Karlo_Moharic on June 29, 2018, 11:32:15 pm ---Don't use glass fuses , instead use either resettable fuse or HRC fuse , which ever you can get cheaper , the minimum voltage rating of a fuse needs to be 300V.
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HRC fuses are total overkill in a plug-in instrument with a 10 W transformer. Standard glass fuses in a holder are totally appropriate here, and almost universally used in such situations.
FlyingHacker:
If you want to explore transient suppression, depending on your environment and type of loads, etc., have a look at this article from ON Semi:
http://www.industrologic.com/transient.pdf
exe:
--- Quote from: Karlo_Moharic on June 30, 2018, 09:38:13 pm ---In case of HV surge , easily blows up , sending glass everywhere and damaging nearby components
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I use EMI filters with built-in fuse holders. Fuse slots are contained, so in case of explosion glass won't be spread (no sure about damage to the filter). There are also fully enclosured fuse holders. Like this one: https://www.tme.eu/en/details/0031.3501/pcb-fuseholders/schurter/ . There are also covers available: https://www.tme.eu/en/details/keys4245c/pcb-fuseholders/keystone/4245c/ . Cable fuses are also often fully enclosured: https://www.tme.eu/en/details/8601.2001.08/fuseholders-for-cable/schurter/ .
I wonder if ceramic fuses would be better in this regard. Like this one: https://www.tme.eu/en/details/0001.2501/fuses-5x20mm-time-lag/schurter/ . But, of course, the physical size limits maximum voltage it can withstand. So, if a surge in the order of kV it won't help.
I mean, HRC would be event better, but they are expensive :/ . On the other side, I read transformers (due to implicit high inductance) are quite robust to surges.
Anyway, I don't want to make any suggestions, just offering alternatives to a classic open fuse holder and a glass fuse.
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