Sensor failures

khalid4145 · #1 03-10-2010, 03:29 PM

Dear all,,,

What are the failure causes of the following:

1- Voltage sensors.

2- Current sensors of current transducers

how can the fault be detected in both types?.

KMoffett · #2 03-10-2010, 05:01 PM

Since there are different types of sensors for both voltage and current, you will have to be very specific to the sensor you're interested in: manufacturer/model.

Ken

ziouranio · #3 03-10-2010, 05:12 PM

it's quite a generic question....
smells like a school homework question I guess.

Voltage meters can be commonly damaged by applying overvoltages exceeding a certain tolerable limit. But they can die even when a test lead is interrupted (whoever owns a mutlimeter may have experienced that sometimes the test leads dies after many bends of the wires).

Galvanometers or current meters can be damaged by overcurrents, that generally happens with cheap multimeters when you forget that the leads are connected to current measure position and you try to read the voltage between the power supply rails. Test lead interruption is again another problem source. Usually multimeters have a cartidge fuse protection in series with the current measure shunt resistor, at least at lower current ranges.

When considering the current measure transformers (used on AC distribution networks) I remember that another safety problem could arise due to huge current glitches, since the transformer circuit turns the glith into a dangerous voltage pulse at its secondary side. Usually a spark gap or a transient suppressor is used to suppress it.

khalid4145 · #4 03-10-2010, 08:59 PM

Ken,,,

The current transducer which i used is from LEM company called LTS 15-NP. what are the common causes of failueres for this type of current transducer.

Ziouranio

Thanks for the detailed information but i am not talking about neither voltmeter nor current meter!!!! I am talking about sensors that can be feeded back to a microcontroller.

retched · #5 03-10-2010, 09:40 PM

Shock, temperature, Static electricity, and over current/voltage can all cause failure of these sensors .

KMoffett · #6 03-11-2010, 12:03 AM

http://www.lem.com/docs/products/lts%2015-np%20e.pdf gives you some maximum parameters that could cause failure if exceeded. A failure might be indicated by a full scale output or zero output if there was another parameter in your system that would indicate that those were not expected. You could email LEM and discuss your specific application and need with their engineers.

Ken