Chapter 4—Metering Capabilities

63230-300-212

Min/Max Values for Real-time Readings

April 2001

 

 

 

instructions on working with logs using SMS, refer to the SMS online help file

 

included with the software.

Power Factor Min/Max Conventions

All running min/max values, except for power factor, are arithmetic minimum

 

and maximum values. For example, the minimum phase A–B voltage is the

 

lowest value in the range 0 to 1200 kV that has occurred since the

 

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

 

midpoint is unity (equal to one), the power factor min/max values are not true

 

arithmetic minimums and maximums. Instead, the minimum value represents

 

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

 

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

 

to +0 on the same scale.

 

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

 

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

 

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

 

minimum power factor need not be lagging, and the maximum power factor

 

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

 

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

 

maximum power factor would be –.95 (lagging). Both would be negative.

 

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

 

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

 

positive in this case.

Minimum

 

Range of

Maximum

 

Power Factor

Power Factor

Power Factor

–.7 (lagging)

Values

.8 (leading)

 

 

 

Unity

 

 

 

 

1.00

.8

 

 

 

.8

 

 

 

.6

.6

 

Lag

.4

 

.4

Lead

(–)

 

(+)

 

 

 

 

.2

 

.2

 

 

 

–0

+0

 

 

 

Note: Assumes a positive power flow

 

Figure 4–1: Power factor min/max example

An alternate power factor storage method is also available for use with analog outputs and trending. See the footnotes in Appendix A— Abbreviated Register Listing on page 127 for the applicable registers.

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© 2001 Schneider Electric All Rights Reserved

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Image 66
Schneider Electric 4000 manual Included with the software, Power Factor Min/Max Conventions, To +0 on the same scale