Schneider Electric PM820, PM870, PM810, PM850 manual Sliding Block, Fixed Block

63230-500-225A2	PowerLogicTM Series 800 Power Meter
3/2011	Chapter 4—Metering Capabilities

Block Interval Demand

In the block interval demand method, you select a “block” of time that the power meter uses for the demand calculation. You choose how the power meter handles that block of time (interval). Three different modes are possible:

•Sliding Block. In the sliding block interval, you select an interval from 1 to 60 minutes (in 1-minute increments). If the interval is between 1 and 15 minutes, the demand calculation updates every 15 seconds. If the interval is between 16 and 60 minutes, the demand calculation updates every 60 seconds. The power meter displays the demand value for the last completed interval.

•Fixed Block. In the fixed block interval, you select an interval from 1 to 60 minutes (in 1-minute increments). The power meter calculates and updates the demand at the end of each interval.

•Rolling Block. In the rolling block interval, you select an interval and a sub-interval. The sub-interval must divide evenly into the interval. For example, you might set three 5-minute sub-intervals for a 15-minute interval. Demand is updated at each sub- interval. The power meter displays the demand value for the last completed interval.

Figure 4–4below illustrates the three ways to calculate demand power using the block method. For illustration purposes, the interval is set to 15 minutes.

Figure 4–4: Block Interval Demand Examples

	Calculation updates		Demand value is the
	every 15 or 60		average for the last
	seconds	15-minute interval	completed interval
				Time
15 30 45 60 . . .				(sec)

Sliding Block

			Demand value is
	Calculation updates at		the average for
	the end of the interval		the last
			completed
			interval
15-minute interval	15-minute interval		15-min
			Time
15	30	45	(min)
	Fixed Block

Calculation updates at the end of	Demand value is
the sub-interval (5 minutes)	the average for
	the last
	completed
15-minute interval	interval

								Time
PLSD110131	15	20	25	30	35	40	45	(min)
					Rolling Block

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