Encapsulated transformers instead of traditional switching power supplies like Hi-Link
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Isn't hi-link a little more efficient than a standard transformer? I mean it shouldn't get that warm
@gohan I don't know how to compare efficiency of such different devices.
According to http://lygte-info.dk/review/Power Mains to 5V 0.6A Hi-Link HLK-PM01 UK.html maximum efficiency of Hi-Link is about 70%, but efficiency decreases at low currents down to 40-50%.
If you want I can measure current in input winding (230V) of transformer with load and without load.
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@gohan 8.3 mA AC at no load, 8.4 mA AC at load (~40 mA DC at low-voltage side), 11.2 mA AC at secondary winding short circuit. 225 V AC mains voltage. About 1.87 VA (~1.35 kW*h per month?) according to my calculations for enviroment heating. Primary winding resistance 6.47 kOhm.
Also I have tried second (slightly bigger, but 3 times more powerful, green on my photos) 1.5VA transformer. 7.8 mA at no load, 30.0 mA at secondary winding short circuit. 13.1 V AC no load voltage at secondary winding. Primary winding resistance is 3.32 kOhm. After 10 minutes of work without load transformer is much colder than the smaller one. Fingers do not feel much difference in temperature between the table and the transformer.
I'm using cheap Chinese DT9208A multimeter.
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So basically the small transformer is pretty much a small heater since the energy absorbed with or without load is almost the same 😁
@gohan you are right, somebody can use such transformers as heaters 🔥
Yes, transformers are not very efficient, but overall power usage is acceptable at least for me. But what about other things such as safety, galvanic isolation, reliability, high frequency noise, Y-capacitors between high-voltage and low-voltage sides, the need to add external circuitry (varistors, fuses, etc) for switching PSUs and so on?
Somebody tried to measure no-load current at 230V side of switching PSUs like Hi-Link? And PSU temperature at low loads?
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@gohan you are right, somebody can use such transformers as heaters 🔥
Yes, transformers are not very efficient, but overall power usage is acceptable at least for me. But what about other things such as safety, galvanic isolation, reliability, high frequency noise, Y-capacitors between high-voltage and low-voltage sides, the need to add external circuitry (varistors, fuses, etc) for switching PSUs and so on?
Somebody tried to measure no-load current at 230V side of switching PSUs like Hi-Link? And PSU temperature at low loads?
@robosensor said in Encapsulated transformers instead of traditional switching power supplies like Hi-Link:
Somebody tried to measure no-load current at 230V side of switching PSUs like Hi-Link? And PSU temperature at low loads?
Maybe late to bring up an old thread but I couldn't resist.
I thinks it's a good idea to use the old school transformer-recitifier solution for the safety aspect. I do it in some cases (unless price, space or efficiency requirements). If you want some more reference data, I did a review of one SMPS I use, over here: https://forum.mysensors.org/topic/3428/my-look-at-a-cheap-12v-power-supply -
@robosensor said in Encapsulated transformers instead of traditional switching power supplies like Hi-Link:
Somebody tried to measure no-load current at 230V side of switching PSUs like Hi-Link? And PSU temperature at low loads?
Maybe late to bring up an old thread but I couldn't resist.
I thinks it's a good idea to use the old school transformer-recitifier solution for the safety aspect. I do it in some cases (unless price, space or efficiency requirements). If you want some more reference data, I did a review of one SMPS I use, over here: https://forum.mysensors.org/topic/3428/my-look-at-a-cheap-12v-power-supply@m26872 thank you, great review! As far as I understand, no-load power usage is 0.57W (or 1.05W?) vs 1.87W (for small) or 1.76W (for big transformer).
So up to three times more no-load power usage for regular transformers. But in any case overall power usage is still acceptable for me because I sleep better with such transformers :joy:
Now I'm moving to solar-powered sensor nodes where it's possible.
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@m26872 thank you, great review! As far as I understand, no-load power usage is 0.57W (or 1.05W?) vs 1.87W (for small) or 1.76W (for big transformer).
So up to three times more no-load power usage for regular transformers. But in any case overall power usage is still acceptable for me because I sleep better with such transformers :joy:
Now I'm moving to solar-powered sensor nodes where it's possible.
- If I remember 0.57W or 1.05W was unpredictable and depending on/off times.
- Your comparison with your transformers sounds realistic I think.
- Good for you if you can live on solar power, for me the sunny season is too short.
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- If I remember 0.57W or 1.05W was unpredictable and depending on/off times.
- Your comparison with your transformers sounds realistic I think.
- Good for you if you can live on solar power, for me the sunny season is too short.
@m26872 said in Encapsulated transformers instead of traditional switching power supplies like Hi-Link:
for me the sunny season is too short.
I havn't yet tried to use solar batteries in winter so maybe I have the same problems (despite the fact that I'm living 3 degrees south of you), but I have backup solution for very cloudy winter days - regular battery charger.
