10.7 How Energy is Totalized in the Model 1133A
109
10.6.3
Sequence Values
Symbol
Description
Values Included
No.
VH, V2H
Sequence Voltages and Currents
0,1,2VH, 0,1,2V
2
H
0,1,2AH, 0,1,2A
2
H
12
10.6.4
Frequency Variation Values
Symbol
Description
Values Included
No.
Freq Var Ave Err
Freq. Variation Ave. Error
1
Sudden Freq Var
Sudden Frequency Variation
1
10.6.5
Flicker
Symbol
Description
Values Included
No.
Flicker AV
Voltage Flicker
A, B, C phase
3
Flicker BI
Current Flicker
A, B, C phase
3
10.6.6
Harmonics
Symbol
Description
Values Included
No.
AV 2
Voltage Harmonic
A, B, C phase, fund. - 50th
150
BI 3
Current Harmonic
A, B, C phase, fund. - 50th
150
AV RMS THD
Volt. Total Harm. Distortion
A, B, C phase
30
Total Values
330
10.7
How Energy is Totalized in the Model 1133A
When scheduled data are downloaded from the 1133A, it is organized according to individual
phase and also by the totals of all phases. Also, it is further divided according to its direction
of flow – whether delivered (DEL) or received REC) by the power company. Therefore, energy is
recognized as bi-directional as far as the 1133A is concerned and separated into those categories.
Lastly, there are two measurement times to consider: the instrument interval (20/second) and a
measurement period set by the user called Frequency. While the measurement interval was chosen to
provide accurate analysis of the power, the Frequency provides a period of time over which power is
measured and recorded, as energy accumulates in a register. At the end of the measurement period,
the accumulated values for scheduled energies are copied to the 1133A flash memory module. Also,
the registers are cleared to zero for the next cycle.
Suppose that the measurement period for a three-phase system is set to five minutes. During
the next five minutes, the 1133A will measure the active power for each phase and calculate totals
for all the phases. If the active power is negative, then it is regarded as received and added to the
REC register. If the active power is positive, then it is regarded as delivered and added to the DEL
register. For a three-phase system, all phases are added algebraically to produce the total. If the
total is positive, it is placed in the Total Wh DEL register. If the total is negative, it is placed in
the Total Wh REC register. When the timer reaches five minutes, the contents of each register is
copied into a flash memory location and cleared for the next scheduled period. When downloaded,
all energy is displayed as positive, but separated in to their respective REC or DEL columns.
