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It is attached to a Keithey 2380 dc Electric load (the manual is ummmm... not that great)
I have the 2380 in "Constant Current" mode.
The display of the 2380 says 1.2v at 0A (this makes sense)
When I turn up the constant current to 1A the display says 1V 1A 1W... which I assumed meant that the output of the buck regulator was drooping...
The problem is that when I measure the output of the buck with a volt meter it is still 1.2v
Where did the 0.2V go?
The more I turn up the current the lower the voltage goes.
Obviously it is displaying some other voltage than the input to the 2380... but what it it?
Then things get even more confusing. When I put another meter in the current path I get exactly the same current measurement as the 2380 (that's good)... it reads 1A as well... BUT... the voltage displayed on the 2380 goes even lower.... 0.31v but still 1A
What is the display really telling me?
I am pretty sure that the impedance of the path is something like 0.1ohm... and that is where the voltage is going.
What I don't understand is:
#1 why not measure the voltage at the inputs?
#2 why bother to show the voltage and power if it is not the real power and voltage? (for me when I set the 2380 at CC=1A and the voltage at the terminals is 1.2v ... then the display should show 1.2W and 1.2V .... not whatever the lower voltage (and power) is.
- Keithley Applications
- Posts: 1576
- Joined: October 15th, 2010, 10:35 am
- Country: United States
When you inserted the amp meter, the load reports even lower voltage, because now the amp meter voltage burden drops part of the 1.2v too.
Sketch: By connecting and enabling use of the remote sense, the voltage measurement will be taken where you connect them. Similar to when you connected in and measured the buck converter voltage with a dmm volt meter.
https://iotexpert.com/2020/02/18/keithl ... e-sensing/
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