Monitor the cost of running your mains electrical appliances

PIC-Electric Mk2 is a considerably more sophisticated version of a design published in EPE about nine years ago. Whereas the original basically monitored the cost of running a single mains a.c. electrical appliance in realtime, the Mk2 provides data logging facilities for two appliances, each independently connected to its own logging path.

As with the original PIC-Electric, Hall-Effect current transducers are used in this design. This project supports the following features:

• PIC16F876 microcontrolled
• 230V/110V 50Hz/60Hz compatible
• 2-channel monitoring – second channel optional
• L.C.D. display of real-time values for:
• • Mains a.c. voltage, up to 250V a.c., including 110V a.c.
• Appliance load current, up to 25A per channel
• Appliance power consumption, up to 6kW per channel
• Cumulative cost since start of monitoring, to 999.99 units
• User selected cost per kWh value, any decimal currency
• Elapsed time since unit's power-up

• Optional on-board serial logging memory for:

• Mains a.c. voltage
• Appliance load current, 2 channels

• Logging capacity approximately 68 hours at 1-minute sampling rate
• Cyclic recording, 0 to maximum memory, roll-over to 0, continue, etc
• Output of recorded data to PC-compatible computer, Windows 95 upwards
• Specially written PC program for data storage to disk for subsequent display and analysis
• Stand-alone program written in Visual Basic 6 (does not need VB6 to be installed on PC)
• Data files compatible with Windows Excel graphing and analysis software

It must be noted that this design should only be built by those who are suitably qualified or supervised. Mains electricity can kill!