Specifications

63230-507-201A1 Power Meter 750

03/2007 Section 4—Metering

Demand Current The power meter calculates demand current using the thermal demand

method. The default interval is 15 minutes, but you can set the demand

current interval between 1 and 60 minutes in 1-minute increments.

Peak Demand In nonvolatile memory, the power meter maintains a running maximum for

power demand values, called “peak demand.” The peak is the highest

average for each of these readings: kWD, kVARD, and kVAD since the last

reset. Table 4– 2 on page 16 lists the available peak demand readings from

the power meter.

You can reset peak demand values from the power meter display. From the

Main Menu, select MAINT > RESET > DMD.

You should reset peak demand after changes to basic meter setup, such as

CT ratio or system type.

ENERGY READINGS The power meter calculates and stores accumulated energy values for real,

reactive, and apparent energy.

You can view accumulated energy from the display. The resolution of the

energy value will automatically change through the range of 000.000 kWh

to 000,000 MWh (000.000 kVAh to 000,000 MVARh).

Energy values can be reported over communications in two formats: scaled

long integer and floating point. The units are always kWh, KVARh, or kVAh.

The long integer values are limited to 2,147,483,647 x the scale factor. The

floating point values are limited to 1.84 x 10

POWER ANALYSIS VALUES The power meter provides power analysis values for Total Harmonic

Distortion (THD). THD is a quick measure of the total distortion present in a

waveform and is the ratio of harmonic content to the fundamental. It

provides a general indication of the “quality” of a waveform. THD is

calculated for both voltage and current. The power meter uses the following

equation to calculate THD where H is the harmonic distortion:

Figure 4– 2: Thermal Demand Example

15-minute

interval

15-minute

interval

Time

(minutes)

Calculation u

dates at the end of each interval

The interval is a window of time that moves across the timeline.

Last completed

demand interval

99%

90%

% of Load

100%

THD =