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5
Reading and Interpreting MJ-5 Control Panel Data
kWhr F and kWhr R (Forward and Reverse Real
Energy)
The Forward and Reverse kWhr data items display
Kilowatt Hour values. They are accumulated separately for
forward and reverse power flow conditions. kWhr is
updated once per second, using the formula:
kVARhr F and kVARhr R (Forward and Reverse
Reactive Energy)
The kVARhr F and kVARhr R data items display Kilovar
Hour values. They are accumulated separately for forward
and reverse power flow conditions. The kVARhr is updated
once per second, using the formula:
The microprocessor computes and accumulates kVARhr
values for each of the four quadrants of the voltage/current
phase-angle relationships. These parameters are presented
as shown in Figure 5.1.
Figure 5.1 Power Quadrant Conventions
5.4 Demand Data—
The <DEMAND> Menu
Demand measurements are time integration functions of the
metered values. The MJ-5 Control Panel performs demand
calculations for the following data items: voltage, current,
power factor and power.
Demand data is maintained separately for forward and
reverse power flow conditions (see Table 5.4). During
forward power flow conditions, the microprocessor does
not accumulate reverse measurements. During reverse
power flow conditions, the microprocessor does not
accumulate forward measurements.
You can select one of two methods of measuring demand:
the Sliding Window method and the Thermal Averaging
method. See DmdType in Section 4.3.23.
Siemens Industry, Inc.
Table 5.4 Demand Data Items
1.
Instantaneous, min and max data available
2.
For each Forward Demand Data Item there is a
corresponding Reverse Demand Data Item. For example,
Rdmd Vld.
To retrieve Demand data, select the appropriate, <FW
DEMAND> or <REV DEMAND>, menu. Then, use the
▲ and ▼ keys to sequence through the Demand data items.
To view the minimum and maximum values for a given
Demand data item, first view the present value; then use the
Max/Min key to display the respective maximum and
minimum values recorded since the last reset.
Demand calculations are initialized at the time of system
power up, when configuration items are changed, and on
any power flow reversal. Un-initialized data items are
presented as dashes (—) on the display screen. Demand
values remain un-initialized until completion of the first
subperiod. Power factor is stored whenever a new kVA
maximum or minimum demand value is reached. These
Power Factor values are reset when kVA max or kVA min
values are reset.
5.5 Event Log - The <EVENT LOG>
Menu
The MJ-5 can be set up to record meter data at the time of
an "Event." Events can include: power up, parameter
changes, tap changes, etc. Use the <LOG SETUP> menu
to enable the Events you want logged (see Section 4.5).
Table 5.5 describes the data that is to be logged whenever
an Event occurs.
Table 5.5 <EVENT LOG> Data Items
1.
The Event number is a sequential number used for
maintaining and referencing the <EVENT LOG>
39
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