TELL ME THE EFFECT ON CURRENT IN VFD MOTORS.

A motor connected to a VFD does not need an overload relay, the VFD provides the motor overload protection (that's part of its job, and it does it better than a standard overload relay too). All you need to do is provide suitable protection (circuit breaker or fuse) on the primary side of the VFD.

For more information consult your VFD manual, wikipedia (or the rest of the internet) and you local electrical standards. Also please don't shout in capital letters (I just got out of bed).

WHAT IS THE EFFECT ON MOTOR'S CURRENT IF IT IS CONNECTED TO V.F.D.& WHAT WILL BE ITS O/L RELAY RANGE?

Are you doing a project-work? If you bought a VFD now, your VFD manual will tell you how to set the O/L tripping in VFD. Any how here are answers.

Output of a VFD will be in PWM (Pulse Width Modulated) form. This PWM Current will get converted into Sine Wave (not in its pure form but with some sawtooth edges) inthe motor itself. The quality of this sinewave depends on the Switching Frequency set in VFD - higher the switching frequency higher the quality and lower the noise made by motor. The equivalent RMS value of this motor current can be seen in the VFD display.

Overload relay function in a VFD is given in % of motor rated Full load current which is to be set during initial set up (see your VFD manual for this). VFD can monitor both Thermal and Rate of rise characteristics of motor current.

Hope your queries are answered.

Finally, my suggestion to you is "read your VFD's Manual completely & patiently first".