The BEMS measurement and analysis of
electrical power is designed to be used with Kilowatt-Hour meters.
The BEMS takes a difference in readings every 5 to 15 minutes to
calculate the Kilowatts used over that period.

It is important that the Kilowatt-hour
meters do not “turnover”, resulting in negative energy use
calculated for that period.

There is no provision in the BEMS to
change the units or scaling.

However Calculation tags could rescale
the watt-hour meter to Kilowatt-hour and the Calculation block be
used for input to the BEMS.

Similarly, Accumulation tags could be
used to calculate Kilowatt-Hours from watts or kilowatts.

The drawback to using Accumulation Tags
or other software methods to calculate Kilowatt hours is if the PC
stops or is restarted. If the calculated kilowatts are set to
zero, then large negative values for Kilowatt-hour may be
calculated for the next 5 or 15 minute period.

Each SCADA node communicates to
kilowatt-hour meters either directly or indirectly through
automation equipment (PLCs, DCS, IO, etc) using the communication
drivers supplied with WebAccess.