I am on the ground...U guys really crack me
What happened to the OP

 

Humour me. The stage is yours.

You are still getting confused between a protective earth point and a reference point. They are not necessarily the same point nor do they need to be.

 

You are still getting confused between a protective earth point and a reference point. They are not necessarily the same point nor do they need to be.

This is an explanation?

I agree that a protective or any other sort of earth is not the same thing as a reference point. A circuit can have one or both or neither. An earth can be used as a reference.

In other words an earth and a reference are different things.

The OP inquired about the difference and there were several fuzzy replies so why the smart alec comments?

I also suggested a forums earch as this subject has been raised and debated many times. Did you do this?

I think (lots of) examples help in this situation.

For the record

I identify three uses of earths in general viz

Protective earth
Screening/shielding earth
Voltage reference earth


You can spend lots of time dreaming up examples, mine are meant to be thought provocative. Here are a few more.

A power supply reference voltage provide by zener or reference IC may have one end connected to zero, but the reference voltage is definitely not earthed.

Zero volts may be used a a 'signal earth'. Then the signal is 'earth referenced'

Alternatively the signal may be floating (perhaps from a transformer) although the circuit itself may possess an earthed zero rail.

Again the floating signal above may use an isolated chassis as a 'chassis or frame earth'.

Neither terminal of an automotive vehicle is earthed. One terminal is often connencted to chassis and called chassis ground.

Two 'earths' may be at different potentials. Suppose we have a signal source and an amplifier, both with zero referenced signals. If we connect these via a screened cable we do not connect the screen at both ends to zero in case the 'zeros' are at different potentials. Another reason is to prevent a hum loop.

 

This is an explanation?

I agree that a protective or any other sort of earth is not the same thing as a reference point. A circuit can have one or both or neither. An earth can be used as a reference.

In other words an earth and a reference are different things. So you agree with me at last.

The OP inquired about the difference.

Did he/she? If you can understand the English and what was really meant by "Why we consider ground or reference point in electronic circuit. " you're a better man than me Gungadin.

The only point I made was that an earth is not necessarily the same thing as a reference point.