Dear Sir, Thank you for your interest in our product lines. Your design is probably getting too close to saturation. We recommend designing the burden resistor such that the voltage across the CT is 100 mV. So for a full scale of 15 amps, output is 65 mA, and the burden resistor should be .1/.065 = 1.5 ohms. Then gain up the op amp for the required output voltage. Thank you for your business.
