Any suggestions/experience for including circuit breaker analyzer (Megger EGIL) in Medium Voltage Circuit Breakers preventive maintenance plan.( Rated:6.3kV)?

I believe that the best preventive maintenance to do for medium voltage circuit breakers is to diligently follow the operations and maintenance manual that is provided by the manufacturer.

Most important also is to follow the field testing requirement when the new breakers are installed (pre-operation and commisioning tests)

The most qualified people to do the analysis of your circuit breakers are the service technicians / engineers of your breaker manufacturer or supplier. They know their equipment. You can use an analyzer but you may not accurately provide the correct prognosis. Even if you get a diagnostic result I recommend that you do not tinker or play with your circuit breaker mechanisms. Let the service engineers / technicians of your circuit breaker manufacturer / supplier do it for you, because circuit breakers are fault rated and its mechanisms are engineered precisely to react with time (speed) and force (strenght) to interrupt fault currents (interrupting capacity) that it was designed for.

There are many types of CBS viz,ACB,VCB and SF6.Each type will have its own mechanism for closing,opening and spring charging.It is always recommended that major overhauls be entrusted to Original equipment supplier. In the manuals the manufacturer would indicate user serviceable parts and a list of mandatory spare would also be available.The primary preventive maintenance shall be the premises shall be devoid of dust and moisture..An annual test of IR values,contact resistance and operating time would be least necessary.

just to add... regularly check the gas decomposition test for SF6, moisture test for ACB and vacuum integrity test for VCB (at least once per 2 years)... always refer and contact your OEMs or to competent specialty contractors...

You have indicated that your circuit breaker is a medium voltage circuit breaker 6.3 KV. Mostly at this voltage the circuit breakers are draw-out type. Draw it out and do your regular PM. If it is an old ACB you can see and clean your contacts. If it is vacuum then you can test your vacuum bottles. I do not think your CB is SF6 because it is only 6.3 KV.

CB analyser is mostly not needed for MV switchgears.
This is mostly neded and applicable for EHV applications.

I agree with SEKHARS opinion.

Shahzad , you don't need breaker analysis in your regular PM, it is required during first commissioning or after major overhaul, major overhauling generally depends on certain number of operations or years as instructed by OEM