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Reference Designs

Zero drift PGA based Analog Front End Design for Circuit Breakers (ACB/MCCB-ETU)

Texas Instruments

This reference design is intended for use in molded case circuit breakers (MCCB) electronic trip units. The programmable gain amplifier based design acts as the current monitoring for over-current earth fault relays. Utilizing a zero drift programmable amplifier: this design provides a ±10 % pick-up (A) accuracy and time delay (s) accuracy of 0 to -20%. Additionally: this solution was designed to handle harsh environment conditions by including features such as ambient insensitivity from -10 to 70 ⁰C and high electromagnetic immunity. Finally the analog front end of this design interfaces seemlessly with the TI MSP430 MCU for quicker evaluation and faster time-to-market.

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Features

Architecture enables the customer to easily create multiple circuit breaker models with different current rangesUsing programmable gain control: fault current sensing range can be increased to > 10 times Ir and Lower total manufacturing cost with reduced component count and less calibration time vs. discrete opamp based electromechanical solutionRobust design with ambient insensitivity from -10 to +70 °C and better trip time repeatability vs. discrete opamp based electromechanical solutionWide input DC-DC converter with under voltage and overcurrent protectionSelf-power (CT powered) supply with reduced CT loading and lower power loss