The circuit i have consists of one circuit which can carry anything up to
50Adc at 12vDC. A shunt resistor (60mV = 100A) is placed in series with this
circuit and thus produces a voltage drop between 0mV and 60mV depending on the current. Iam tyring to read this voltage into a PLC and i have placed an
op-amp circuit giving me a gain of 50. This op-amp circuit is supplied via a 24vDC supply and i have commoned the two power supplies. My problem is when i measure the voltage across the shunt i get for example 10mV however when i measure across the 4.7uf capacitor (see circuit) i end up getting something like 16mV. What i dont understand is that the + and - of the shunt and the + and - of the capcitor are effectively the same points in the circuit?
With the mV signal i would have expected a voltage drop due to maybe the wiring which i've shortened as much as i can but there still seems to be this error? if anyone knows of another way of acheiving the same thing with the shunt i would appreciate it?
Thanks
50Adc at 12vDC. A shunt resistor (60mV = 100A) is placed in series with this
circuit and thus produces a voltage drop between 0mV and 60mV depending on the current. Iam tyring to read this voltage into a PLC and i have placed an
op-amp circuit giving me a gain of 50. This op-amp circuit is supplied via a 24vDC supply and i have commoned the two power supplies. My problem is when i measure the voltage across the shunt i get for example 10mV however when i measure across the 4.7uf capacitor (see circuit) i end up getting something like 16mV. What i dont understand is that the + and - of the shunt and the + and - of the capcitor are effectively the same points in the circuit?
With the mV signal i would have expected a voltage drop due to maybe the wiring which i've shortened as much as i can but there still seems to be this error? if anyone knows of another way of acheiving the same thing with the shunt i would appreciate it?
Thanks
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