7i76e burned - after setting up VFD
17 Jul 2020 19:19 #174955
by denhen89
Replied by denhen89 on topic 7i76e burned - after setting up VFD
Thank you guys.
Its sure that i will never ever again do that, not even on other electrical devices, but i would like to understand why that kind of ?voltage? peaks happening?
I have tried to google that, but i think i am entering the wrong keywords. I dont expect to get an explanation, but it would be if you could tell me how to find informations about that.
Thanks in advance.
Its sure that i will never ever again do that, not even on other electrical devices, but i would like to understand why that kind of ?voltage? peaks happening?
I have tried to google that, but i think i am entering the wrong keywords. I dont expect to get an explanation, but it would be if you could tell me how to find informations about that.
Thanks in advance.
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17 Jul 2020 19:48 - 17 Jul 2020 19:56 #174956
by PCW
Replied by PCW on topic 7i76e burned - after setting up VFD
Basically if you have electronic devices with DC power
(say a power supply and a motor drive) Both devices will have
likely have bypass capacitors. So if you connect one device that is charged
(say a power supply) to a device with 0 voltage across its
capacitors, a large surge current will flow between the capacitors
limited only by the capacitor internal resistance and wiring inductance.
This can cause current surges from the 10s to 1000s of Amps
depending on the capacitors, wiring and voltage difference.
The current surge can also cause a voltage surge because
of stored energy in the wiring inductance.
(say a power supply and a motor drive) Both devices will have
likely have bypass capacitors. So if you connect one device that is charged
(say a power supply) to a device with 0 voltage across its
capacitors, a large surge current will flow between the capacitors
limited only by the capacitor internal resistance and wiring inductance.
This can cause current surges from the 10s to 1000s of Amps
depending on the capacitors, wiring and voltage difference.
The current surge can also cause a voltage surge because
of stored energy in the wiring inductance.
Last edit: 17 Jul 2020 19:56 by PCW.
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17 Jul 2020 20:19 - 17 Jul 2020 20:21 #174960
by tommylight
Replied by tommylight on topic 7i76e burned - after setting up VFD
You would think that internet has answers to any question, then i can not find anything useful about this.
This has some info about not switching the DC side of electronics:
www.google.com/search?ei=fgUSX-udEO6Bk74...yjChMQ4dUDCAs&uact=5
The top 3 results and another lower link to Kollmorgen.
I am sure that is true for all the electronics that have inductive loads on them, any switching of the DC side will end up in smoke if they are powered and enabled. I am also sure all chips have a rate at what the voltage supplying them can rise, but i will leave this to PCW as he is the ultimate expert on these subjects.
Ha, to late, was searching and finding nothing useful.
Thank you PCW.
This has some info about not switching the DC side of electronics:
www.google.com/search?ei=fgUSX-udEO6Bk74...yjChMQ4dUDCAs&uact=5
The top 3 results and another lower link to Kollmorgen.
I am sure that is true for all the electronics that have inductive loads on them, any switching of the DC side will end up in smoke if they are powered and enabled. I am also sure all chips have a rate at what the voltage supplying them can rise, but i will leave this to PCW as he is the ultimate expert on these subjects.
Ha, to late, was searching and finding nothing useful.
Thank you PCW.
Last edit: 17 Jul 2020 20:21 by tommylight. Reason: More info
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17 Jul 2020 20:42 #174965
by denhen89
Replied by denhen89 on topic 7i76e burned - after setting up VFD
It makes totally sense for me. Especially after i have read about what are bypass capacitors 
Thanks!
Thanks!
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30 Jul 2020 17:18 #176545
by stefan63
Replied by stefan63 on topic 7i76e burned - after setting up VFD
Isn't this a sign of bad design, i mean most modern electronics have protection for about everything. A switching power supply for example doesn't simply go dead just because you short the outputs unless you get some really crappy stuff. MESA with their experience and reputation should now and do better than that.
Just a thought/Stefan
Just a thought/Stefan
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30 Jul 2020 17:54 - 30 Jul 2020 17:54 #176548
by PCW
Replied by PCW on topic 7i76e burned - after setting up VFD
In general you cannot switch the DC power to power electronics because of the surge currents involved. If you switch the DC power to a step motor drive or a DC powered servo drive you will have trouble. The 7I76e outputs are protected against overloads but you can still cause issues by live switching the field power.
Last edit: 30 Jul 2020 17:54 by PCW.
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30 Jul 2020 18:12 #176552
by stefan63
Replied by stefan63 on topic 7i76e burned - after setting up VFD
Yes but still..
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30 Jul 2020 18:15 #176553
by PCW
Replied by PCW on topic 7i76e burned - after setting up VFD
OK as an experiment, you might try say plugging in the DC power to your step motor drive live...
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30 Jul 2020 18:19 #176554
by stefan63
Replied by stefan63 on topic 7i76e burned - after setting up VFD
I'm actually using and tampering with a lot off electronics and up to now I have never had any issues switching dc side on any raspberry Pi, ESP8366, Arduino ....
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30 Jul 2020 18:22 #176555
by PCW
Replied by PCW on topic 7i76e burned - after setting up VFD
Yep those are 5V or lower voltage powered, not power electronics, big difference
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