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  • Single-Phase Power Monitor Circuit

  • Created: Mar 24, 2017

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Residential devices are mostly in single-phase power that suits to the demand of devices used in this area. The active and reactive power are important parameters that needs to be considered as part of power management and efficient power usage. This design feature power monitoring circuit that can calculates active power, reactive power, RMS current, RMS voltage, power factor, line frequency and other typical power quantities.

This circuit is comprised of several components that will be used in power monitoring and calibration. Since this circuit is an MCP39F501 Power Monitor PICtail evaluation board, it make use of MCP39F501 single-phase, power-monitoring IC with calculation and event detection and serves as the main component. The USB port is for the connection between the board and PC with installed in “MCP39F501 Power Monitor Utility” software. The D+ and D- pin of the USB is connected to MCP2200 IC that handles the USB 2.0 to UART protocol in which it transmit and receive data between USB port and IL721-3E IC isolation barrier. This isolation barrier IC secures data transmission and reception between UART and MPU. The IEC inlet is for the line connection while the IEC outlet is for the load connection. The line input passes through a power supply circuit with MCP1754 IC LDO voltage regulator with an output of 3.3D and 3.3A voltages that correspond to analog and digital supply requirement. The MCP39F501 IC circuit with its external components has the line-neutral connections to the load with inverting (CH0-) and non-inverting (CH0+) pins for current channel. The voltage IN of the load line-neutral is connected to inverting (CHI-) pin for voltage channel while its non-inverting (CHI+) pin is grounded with RC circuit. The configurable digital IOs is connected to OC pins in PICtail connector with Optoisolator or photocoupler that has low input current and darlington phototransistor output. The MCP9700 is a low-power linear active thermistor which is used to measure a relative change of temperature of the system.

The power monitor PICtail evaluation board is suitable in power calibration and monitoring in which in this design it is for single-phase, but few modifications can used for three-phase considering the external components needed. It can also be used in developing devices or applications that requires power data of the systems while in operation.