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Diodes connected to 110VDC Positive & negative supply.... two 110vDC power supply's are connected in parallel.

Rohit Sharma

Dear Team,

We have two power supply's 110VDC connected in parallel to each other. Power diodes are being used in both 110VDC power supply's. I can understand the use of diode in Positive supply, it can block the reverse current flow in other power source if one of Power supply voltage get drop or failed. But what is the sue of diode in negative supply of 110vdc. Pl refer the attached screen shot & share your valuable comments. 

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    The idea that the two diodes in the positive lines prevent feedback from one supply to the other, works only when the negative rails are common, as which ever supply is more positive the diode to the other supply is reverse biased (indeed no current can flow either way through  an anti- series pair of diodes which is in effect what D1 and D2 are)

    But as Graham notes, there may be a very good reason NOT to have the negative rails in common, either to break an earth loop, or to avoid problems during a fault to ground from one line or the other or indeed from the middle of the battery pack. And as a catch-all for this another pair of anti-series diodes, from the lower halves of D1/D2 is a cheap and easy solution.

    It is also the sort of thing we do with electronics that takes shore power and vehicle battery power when we are not too sure what the vehicle is going to be and if there is an earth path or not. (along with protecting against a whole load of other things like over voltage and reverse polarity sudden shut off and a really nasty surge test.)
    Mike

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  • 0

    The idea that the two diodes in the positive lines prevent feedback from one supply to the other, works only when the negative rails are common, as which ever supply is more positive the diode to the other supply is reverse biased (indeed no current can flow either way through  an anti- series pair of diodes which is in effect what D1 and D2 are)

    But as Graham notes, there may be a very good reason NOT to have the negative rails in common, either to break an earth loop, or to avoid problems during a fault to ground from one line or the other or indeed from the middle of the battery pack. And as a catch-all for this another pair of anti-series diodes, from the lower halves of D1/D2 is a cheap and easy solution.

    It is also the sort of thing we do with electronics that takes shore power and vehicle battery power when we are not too sure what the vehicle is going to be and if there is an earth path or not. (along with protecting against a whole load of other things like over voltage and reverse polarity sudden shut off and a really nasty surge test.)
    Mike

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