Hallo Prahlad,

as you have difficulties to get certain little used and exotic components in your region, I have designed a circuit only containing components, which should be easily available for you.

Have look at this:



Instead of TLC277, which shows very low offset voltage you can also use TLC272. But select a type showing little offset voltage then.
This circuit can work with your earlier shown +8V/-7V power supply. In order to decrease influence of power supply fluctuations on signal integritiy, 100Ohm plus 100µF/16V filters should be used. A 16V zenerdiode is connected across supply pins, preventing that supply voltage can rise to dangerous levels. Normally no relevant current should flow through the zener.

A circuit, which is connected to current transformer must be very well protected against surges and EMI. Unfortunately this increases number of components a bit. At input you see a heavy duty transzorb, with a threshold voltage of 24V. Under normal condition this transzorb is far away from being turned-on. Signal degradation due to reverse leakage current of this transzorb is negligible.
What follows is a 101Ohm resistance. Why not 100Ohm?
Because input impedance of rectifier section adds a load of 11kOhm. Without increasing 100Ohm resistor to 101Ohm, you would suffer a signal loss of about 1%. 11kOhm in parallel to 101Ohm just makes 100Ohm, what is needed for your CT.
Input impedance of rectifier is splitted. This allows us to insert low pass filter consisting of 1kOhm plus 1nF. Corner frequency of this low pass filter is 160kHz and decreases EMI. It's important that such an input low pass filter is located BEFORE any active signal stage. At this location efficiency of filtering is much better, than any filter in feedback loop of following OPamp!
As rectifier uses an inverting technique, a very efficient protection scheme can be build to protect inputs of OPamp! This is done by antiparallel diodes from inverting input to ground. Input impedance of rectifier, more concretely the two 20kOhm resistors, serve as current limiters.
It's important to note, that this protection scheme does also work, when power supply is turned-off! Also, this protection scheme does not shunt overvoltages to power supply, where additional circuitry would be necessary to prevent further damage.
Keep in mind, that LinCMOS OPamps are always prone to show latch-up without proper protection schemes! So, added transzorb, RC low pass filter and protection diodes are very helpful.
In the feedback loop 33pF capacitors can be seen. These compensate a bit the phase lag introduced by stray capacitance at inverting input and by capactive load at output. For this, 33pF capacitors provide some phase lead and prevent unsane phase shifts.
Output of rectifier should be connected directly to input of ADC, with shortest connection. This, in order to minimize any capacitive loading at output.
Use fast small signal diodes in this circuit. Something like 1N4151, or similar. Do NOT use 1N400X! Take care that no heavy ambient light can fall onto glass bodies of these diodes. Otherwise leakage current can drastically increase!
In order to keep voltage drops of diodes' leakage current small, which otherwise would introduce additional offset voltages, resistor values are choosen rather low ohmically, in the 10...20kOhm range. Then, influence of leakage currents is negligible. Of course, there are diodes, like FDH300, which show much lower leakage currents and which would allow much higher resistor values. But these diodes aren't easily available...
Resistors' tolerances are critical. You should select resistors by the help of a precise Ohmmeter. With a bit luck, values will differ less than about 0.1% from nominal values. This allows you to avoid these sometimes annoying trimmers.

If you use shielded current transformer and shielded cable, then also circuitry should be shielded. All these shields must connected in such a way, that a continuous Faraday cage whithout any gaps is built. Circuit ground should be connected to the Faraday cage, where the 100Ohm resistor has its connection to signal ground. This should make your circuit work reliably...

Good luck,
Kai