Voltage Divider

Thread Starter

jons

Joined Feb 17, 2012
2
Hi,

I need to monitor a DC charging voltage and have a 4-20ma and a 0-10V input available on my PLC. The charging voltage will flucuate but I'm mainly interested in between 20 and 30 Vdc.

My question is would a simple voltage divider with a pair of resistors to drop the max 30v down to max 10v (I calculated 10K and 5K would take me there abouts) or would these resistors just sit and get excessivly hot?

Any other suggestions?

Cheers

Jon
 

Brownout

Joined Jan 10, 2012
2,390
My question is would a simple voltage divider with a pair of resistors to drop the max 30v down to max 10v (I calculated 10K and 5K would take me there abouts) or would these resistors just sit and get excessivly hot?
P=V^2/R = 30^2/15,000 = 60mW. That's not much power. You only need to make sure that the pin your reading from has much higher resistance. A typical input pin should by > 1M ohm, so usually that's not a problem either.
 
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