Is the pressure regulator same as the pressure reducing valve
The pressure regulator is used for protecting the instruments(sov, positioner etc) from the instrument air(plant air).
A pressure relief valve (PRV) is used for protecting pipe lines from over pressure. It has set limits. When the pressure reached its set limits it will automatically open and release the excess pressure to protect the pipe lines from the over pressure. The regulator has its own outlet pressure setting. A pressure-reducing valve is a control valve and its outlet pressure can be changed remotely.