Hello Everyone,
I hope you are all very well at this moment, I am working on a ship as a marine electrician and I'm not really so much on electronics stuff so I hope you guys can help me with this little problem of mine. I have just replaced our main engine turbo charger tachometer with a new unit as previous unit was found to have a defective analogue output. 4-20mA output signal was not coming out from the unit as I measured it as zero (0mA) and the alarm keeps on coming on our alarm and monitoring system as sensor failed. This is clear to me that the alarm will come out since the issue is on a defective tachometer, so we purchased a new one and after I have installed it, I re-measured the output and it is giving me a 4mA since the turbo charger is not spinning and at 0 rpm. After a while the alarm came off again as sensor failed, so I measured the 4-20 mA output and I still measured 4 mA which is still fine. So I worried that the Analogue input board on that particular channel might be faulty. So I look for other sensors adjacent to it with the same 4 -20mA and then reconnect it to the channel that is in question. It seems like the channel is working fine that it gives a rpm reading with that temporary 4-20mA signal from the other sensors. So now, it is a bit confusing why the alarm is still coming on since the unit is giving a normal 4 mA input. I disconnect the two wires from the tachometer output and measured the voltage and it was 27.31VDC.. Now I'm a bit confused what is going on, why the Analogue input board doesn't want to accept the analogue signal from the tachometer. Is the 27.31 VDC measured is not too much although it is giving a correct mA signal. The analogue input module is set to accept current signals and no alterations made on the wirings and all the settings. I just reconnect the new unit as is but the issue is still there. What seems to be the problem here?
I hope you are all very well at this moment, I am working on a ship as a marine electrician and I'm not really so much on electronics stuff so I hope you guys can help me with this little problem of mine. I have just replaced our main engine turbo charger tachometer with a new unit as previous unit was found to have a defective analogue output. 4-20mA output signal was not coming out from the unit as I measured it as zero (0mA) and the alarm keeps on coming on our alarm and monitoring system as sensor failed. This is clear to me that the alarm will come out since the issue is on a defective tachometer, so we purchased a new one and after I have installed it, I re-measured the output and it is giving me a 4mA since the turbo charger is not spinning and at 0 rpm. After a while the alarm came off again as sensor failed, so I measured the 4-20 mA output and I still measured 4 mA which is still fine. So I worried that the Analogue input board on that particular channel might be faulty. So I look for other sensors adjacent to it with the same 4 -20mA and then reconnect it to the channel that is in question. It seems like the channel is working fine that it gives a rpm reading with that temporary 4-20mA signal from the other sensors. So now, it is a bit confusing why the alarm is still coming on since the unit is giving a normal 4 mA input. I disconnect the two wires from the tachometer output and measured the voltage and it was 27.31VDC.. Now I'm a bit confused what is going on, why the Analogue input board doesn't want to accept the analogue signal from the tachometer. Is the 27.31 VDC measured is not too much although it is giving a correct mA signal. The analogue input module is set to accept current signals and no alterations made on the wirings and all the settings. I just reconnect the new unit as is but the issue is still there. What seems to be the problem here?