NIALMS is an acronym for Non-Intrusive Appliance Load Monitoring. By using this tool in an energy meter a profile of energy (including reactive) used by each appliance can be drawn up. By monitoring fourteen characteristics of each load, the appliances can be identified as well without the meter having to be trained.
The NIALMS is installed within an energy meter, and monitors the power consumed cycle by cycle as well as over longer periods. The abrupt change of power consumed when a new appliance is switched on or off causes a measurement point to be recorded. When plotted in a two-dimensional space we see groups of measurement points which correspond to the same appliance.
By calculating fourteen different parameters associated with each group of points it is possible to separate two similar appliances and calculate the absorbed energy. Even two appliances which occasionally switch simultaneously can be resolved.