KiloWatt-Hour meters

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.