Normally, I don't like to double post, but it was suggested that this forum may be a better place for my question, which was originally posted here.
I am experiencing some trouble with an ABB Mag Master, electromagnetic flow meter and I am hoping that someone with some experience might have some ideas as to what could be the trouble.
The meter is measuring the flow of water (ranging from 45-75 deg F - well within operating range) in the condenser side of a water chiller. On a couple of occasions over the last few months, the meter has started reporting strange values including the positive and negative rails and finally declares an "installation fault" asking if the coil is installed or something similar, but I forgot exactly what.
Prior to the fault condition, monitoring the 4-20mA output, with the connection to the DCS input open circuited, it shows about 30Vdc with a 1V pulse AC that I am reasonably certain is the HART signal. When the unit goes into failure mode, the HART signal all but disappears, though the 30Vdc remains.
We performed an experiment today where the meter was correctly reading zero flow and was reading correctly until the flow reached a certain level at which point the meter stopped reading and the HART signal disappeared. Stopping the flow and closing the valve did not cause the signal to return.
The only installation spec violation that I can see is that the meter was placed too close to a set of elbows / hard bends. Normally, you want 5x pipe diameter before and 2x after. What effect, if any would this violation cause and could it cause the problem seen?
Is there anything else that anyone can think of that could cause the described failure?
I am experiencing some trouble with an ABB Mag Master, electromagnetic flow meter and I am hoping that someone with some experience might have some ideas as to what could be the trouble.
The meter is measuring the flow of water (ranging from 45-75 deg F - well within operating range) in the condenser side of a water chiller. On a couple of occasions over the last few months, the meter has started reporting strange values including the positive and negative rails and finally declares an "installation fault" asking if the coil is installed or something similar, but I forgot exactly what.
Prior to the fault condition, monitoring the 4-20mA output, with the connection to the DCS input open circuited, it shows about 30Vdc with a 1V pulse AC that I am reasonably certain is the HART signal. When the unit goes into failure mode, the HART signal all but disappears, though the 30Vdc remains.
We performed an experiment today where the meter was correctly reading zero flow and was reading correctly until the flow reached a certain level at which point the meter stopped reading and the HART signal disappeared. Stopping the flow and closing the valve did not cause the signal to return.
The only installation spec violation that I can see is that the meter was placed too close to a set of elbows / hard bends. Normally, you want 5x pipe diameter before and 2x after. What effect, if any would this violation cause and could it cause the problem seen?
Is there anything else that anyone can think of that could cause the described failure?
