Power Quality or Power Protection meters are common in many industrial environment. Small units are now available for home use as well. They give operators the ability to monitor the both perturbations on the power line, as well as power used within a building, or by a single machine or appliance. In some situations, equipment function and operation is monitored and controlled from a remote location where communication is via modem, or high-speed communication lines
Various sensors collect performance and condition information on essential station equipment, such as transformers and circuit breakers, and data is stored for future reference. This time-based data will be used to perform specialized functions and provide decision-making guidance to operators, maintenance planners, and engineering.
There are various signal-chain approaches to sample and measure high-voltage power data using TI signal chain solutions:
Using a unipolar analog-to-digital converter (ADC) input, a resistor divider and level shifter is very common for the high input impedance of ADS8364 or ADS8365. The voltage reference in this circuit is 2.5V normally. INA159 is specifically designed for this type of application - To attenuate the signal with only a unipolar power supply. Attempting to build the same circuit with external components could cost more and reduce performance.
Alternatively, TI plans the bipolar input analog-to-digital converters, ADS8556 or ADS8557, which have +/-10V inputs with high impedance and can be used with OPA2211, OPA827, or OPA4277 for signal conditioning and to drive the ADC. This approach will reduce the need for level-shifting circuitry and simplify design.
Designers could save cost by replacing a power module with a TPS65130. This DC/DC converter will generate up to +/-15 supply for bipolar signal conditioning and ADC input requirements.
TI's OMAP-L137 and TMS320C6745 digital signal processors and TMS320F2833 microcontrollers are ideal for processing sampled data and performing FFT type calculations efficiently in power monitoring and control applications, which require a large amount of data sampling and processing to detect the RMS’s of current and voltage, real power, reactive power, harmonics, and high order harmonics. These processors are capable of reacting quickly to overload/over-current, over-voltage, and surge and sag conditions. The C2000 ('F2833x) family of processors are optimized for fast and efficient real-time control; whereas OMAP_L1xx and C674x are optimized for maximum data processing. Finally, the OMAP_L1xx and C674x have operating system support and ENET ports which are often desired by this application space.
The F2833 has on-chip flash and a 12-bit ADC. The integrated 12-bit ADC will not be used in power line current and voltage sensing, but it is perfectly suited to sense environmental and other operation variables.
Interface circuit between boards typically includes CAN, RS485, or M-LVDS with high-speed clock. The advantage of M-LVDS is for high speed data.