| Products > Test Equipment |
| E36300 Series Programmable DC Power Supplies (E36311A, E36312A, E36313A) |
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| nctnico:
And the spike on channel 1 when the mains power is connected hasn't been fixed either :'( I've still got the box! |
| LaurentR:
Got one of these puppies yesterday (E36313A), updated firmware, started using it and... I noticed that the Series mode current is off by (exactly) 10% under some circumstances. E.g. I set (any sufficient voltage), current = 1.000A, the supply reads back 1.000A and my DMM reads back 1.100A. I can set current to pretty much any value and it's exactly 10% off. I did some more experiments with different meters in different modes (e.g. the 34465A exhibits the problem on the 10A range and not the 3A range) and long wires in series... and it seems that it's 10% off under a certain burden voltage (experimentally 200mV) and then gradually becomes correct above that burden voltage. Has this already been reported? Is anyone else seeing this? I did notice this line in the firmware notes "Fixed incorrect configuration on series mode". I am wondering if it's related. It's possible they are compensating for something like internal relay or trace resistance in sw and the sw is confused by the very low voltage. |
| nctnico:
I'm pretty sure it is oscillating. Probably a design trade-off to measure low currents which prohibits using large electrolytics on the output due to their large and time dependant leakage current. Edit: just tried it myself. No oscillations but it only seems to occur when you connect a dead short in series mode. |
| LaurentR:
It turns out that the set Voltage (!) is what makes the issue appear or disappear as shown on the video below. Basically, if the set voltage is below a small multiplier (3-4 in this case) of the burden voltage, it's all fine. But if the set voltage is higher, the burden voltage increases and so does the current until current reaches 1.1x, then both stabilize. In the video, I go up then back down in voltage. As the set voltage crosses 2.5-3V, the transition occurs. The top DMM is showing actual voltage (matches the power supply's voltage readout and the bottom DMM is showing current). |
| nctnico:
Daniel!!!!!! :wtf: :scared: |
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