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| Unstable current measurements on PS w/KP184 DC Electronic Load |
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| LogicalDave:
I have a Tenma 72-8795 (Atten PPS3203) linear bench supply and the current metering is problematic (yes, I know the whole user interface is a disaster, but that's not what this post is about). When I connect the supply to a resistive load, the current meter is stable and correct (within 2mA). However, when I connect the supply to a Kunkin KP184 DC electronic load set for CC mode, the power supply current meter fluctuates wildly. The actual current being drawn by the DC load is correct (Brymen BM789 in series reports same current as the KP184). Are others seeing the same thing? Dueling control loops? Any ideas for how to fix this? |
| Hydron:
See what the Brymen says in AC current mode (should be ~0 if the load is working correctly). If it shows zero, double check with a scope + current shunt (to eliminate DMM analogue bandwidth from being an issue). I bet the control loops in the supply and load are interacting and oscillating like crazy around the setpoint, with the supply showing crazy numbers due to doing less smoothing than the load/meter. |
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