current limiting
current limiting
(OP)
I am having an issue with measuring voltage across an electrolyser cell in a Chlor-Alkali plant. We are just finishing start-up/performance tests and need to resolve this problem. First of all, we have 66 cells with a system voltage of 300V and 100KA which will allow us to have a voltage drop of 4.5V-5V across each cell. The circuit we are using to measure the voltage consists of a fuse and a 10K ohm resistor in series for both the positive and negative side, this is used as an input to an E/I. We are seeing a .1V-.3V voltage drop on the 10K resistor depending on the load, this produces an inaccurate measurment of actual voltage drop across the cell. Are these current limiting resistors absolutely necessary? Is there another way to measure this more accurately? Any help would be appreciated.





RE: current limiting
Ten or twenty kohms should not cause such a high voltage drop if you use a modern DMM. They usually have a 10 Mohms internal impedance, so you should only lose about 0.2 percent, i.e, 10 mV when you measure 5 V.
Of course, if you are lucky enough to have a Simpson or some other goodie, you can have that voltage drop - easily. Then I suggest that you get fused probes instead. They are available with different fuse ratings and have an internal resistance that is orders of magnitude lower.
But do not work without TWO current limiting probes - or fused probes!
Gunnar Englund
www.gke.org
RE: current limiting
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Sometimes I only open my mouth to swap feet...
RE: current limiting
Gunnar Englund
www.gke.org
RE: current limiting
----------------------------------
Sometimes I only open my mouth to swap feet...