A. Electrical Demand metered by a utility is the average kW demand over a discrete interval such as 15 or 30 minutes. The utility meter will average the kW for the time interval, reset to zero and start reading the next interval. The highest average interval value will be billed as a "Demand Charge." On the other hand, one of the 4-20 mA outputs on the new PowerTrak PT-9000 can be set to represent a 15-minute sliding window demand. On thirty second intervals, the KW data from the oldest interval is replaced by the KW data from the most recent interval. This constant updating of the kW usage every scan is called a "Sliding Window Demand Value." The highest "Sliding Window" demand reading may be higher than the utility demand as the PowerTrak updates average demand every 30 seconds and the utility meter may be resetting every 15 or 30 minutes.