CHAPTER 2: ELECTRICAL BACKGROUND

The following figure illustrates another example of energy and demand. In this case, each bar represents the energy consumed in a 15-minute interval. The energy use in each interval typically falls between 50 and 70 kWh. However, during two intervals the energy rises sharply and peaks at 100 kWh in interval #7. This peak of usage will result in setting a high demand reading. For each interval shown the demand value would be four times the indicated energy reading. So interval 1 would have an associated demand of 240 kWh/hr. Interval #7 will have a demand value of 400 kWh/hr. In the data shown, this is the peak demand value and would be the number that would set the demand charge on the utility bill.

 

100

 

 

 

 

 

 

 

 

80

 

 

 

 

 

 

 

hours

60

 

 

 

 

 

 

 

kilowatt-

40

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

20

 

 

 

 

 

 

 

 

0

2

3

4

5

6

7

8

 

1

 

 

 

 

Intervals (15 mins.)

 

 

FIGURE 2–8: Energy Use and Demand Intervals

As seen in this example, it is important to recognize the relationships between power, energy and demand in order to effectively control loads or to correctly monitor use.

EPM 6000 MULTI-FUNCTION POWER METERING SYSTEM – USER GUIDE

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GE EPM 6000 Multi-function Power Metering System instruction manual Energy Use and Demand Intervals