Questions about inductive sensors and hall effect sensors

[cvinyas]

Hello,

I have 2 differents questions.

1. Inductive sensors with air core can accept higher excitation frequencies than iron-core sensors. Why?

2. (Just to verify or not) Sensors based on Hall effect can measure slow changes in magnetic fields but inductive sensors cannot. Why?

A. Hall Effect sensors are zero-order sensors (no element stores energy) and therefore its input has to be at low frequency, so they can measure slow changes. But in inductive sensors, there is at least one element that stores energy (change in reactance), so inductive sensors are able to measure only fast changes.

Please, help me to answer Q1 and verify that A2 is true or not.

Thanks so much for your answers!

Carlos.

 

[FvM]

It's not exactly clear what you mean with "inductive sensors". The most common common kind of inductive sensors are proximity sensors, but their purpose isn't detection of magnetical fields rather than presence of metallic objects.

 

[cvinyas]

Hello,

Yes you are right. Most common inductive sensors are proximity sensors. Varying magnetic fields induce eddy currents on a conductive materials -> Secondary opposing magnetic fields: L changes. So proximity sensors measure how does the impedance (L) change and then traslate that. But I don't know how to answer both questions above.

 

[FvM]

It's impossible to answer the questions without knowing which kind of "inductive sensors" is meant.