BK9103 Remote Sense

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tindel

Joined Sep 16, 2012
780
Recently purchased a BK9103 (42V, 20A, 320W). One of the selling points was the remote sense ability. After reading the manual more closely, I see that there are bunch of warnings saying that you will damage the supply if you turn the supply on or off while using the sense lines. Further, if you short them or reverse the polarity you'll also damage the supply. So I start digging and testing the supply.

I found that the sense circuit is as follows.
1612127871176.png

The green is somewhat conjecture from years of designing supplies myself, but I have never seen remote sense done like this in a bench supply. I have used this architecture in supplies I've designed, but have never considered startup/shutdown to be a realistic failure mode. I agree that shorting the sense lines or reversing them will likely result in a very bad day (and time spent replacing the 10 ohm resistors - and perhaps more), but not turning on/off the power supply while the sense lines are connected to the circuit is a bit far fetched to me. Sure, you can have big current draws during startup / shutdown, but I would think the voltage drop would be reasonable (200mV, max) with adequately sized cables. It seems to me that there's also more risk of damaging the supply due to human error while connecting/disconnecting the sense line after power supply is up and running than connecting the remote sense lines to the load and turning on the power supply.

Am I being too paranoid? What am I missing? Is this just CYA (cover your arse)?

Remote Sense instructions for reference:
9103_9104_series_manual.pdf
1612126819117.png
 
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