Schneider Electric 4000

Chapter 4—Metering Capabilities 63230-300-212

Min/Max Values for Real-time Readings Ap ril 2001

instructionson working with logs using SMS, referto the SMS online help file

includedw iththe software.

All runningmin/max values, except for powerfactor, are arithmetic minimum

and maximum values.For example, the minimum phase A–Bvoltageisthe

lowestvalue in the range 0 to 1200 kV that has occurred since the

min/maxvalues were last reset. In contrast, because the power factor’s

midpointis unity (equal to one), the power factormin/max values are not true

arithmeticminimums and maximums.Instead, the minimum value represents

the measurementclosest to –0 on a continuous scale for all real-time

readings –0to 1.00 to +0. The maximum value is the measurement closest

to+0onthesamescale.

Figure 4–1 below shows the min/max values in a typicalenvironment in

which a positivepower flow is assumed. In the figure, the minimum power

factor is –.7 (lagging) and the maximum is .8 (leading). Note that the

minimumpower factor need not be lagging, and the maximum powerfactor

need not be leading.For example, if the power factor valuesranged from

–.75to –.95, then the minimum power factorwould be –.75 (lagging) and the

maximum power fact or would be –.95 (lagging). Bothwould be negative.

Likewise,if the power factor ranged from +.9 to +.95, the minimumwould be

+.95 (leading)and the maximum would be +.90 (leading). Both would be

positivein this case.

Figure 4–1: Power factor min/max example

An alternate powerfactor storage method is also available foruse with

analog outputsand trending. See the footnotes in Appendix A—

Abbreviated Register Listing on page 127 for the applicable registers.

PowerFactor Min/Max Conventions

Unity

1.00

Lag

(–)

Lead

(+)

–0+0

.2 .2

Minimum

Power Factor

–.7 (lagging)

Maximum

Power Factor

.8 (leading)

Range of

Power Factor

Values

Note: Assumes a positive power flow