C
Appendix
EPQ DataNode Series User’s Guide
C-1
Glossary
Angle between Phases
The phase angle between the Phase Fundamental Voltage
and Current at power line Frequency.
Apparent Phase Power
RMS voltage * RMS current on per phase basis.
Average DPF
Arithmetic average of individual phase displacement
power factors (DPF).
Deadband or Sensitivity
An value programmed as an incremental/decremental
threshold from the last deadband value that would be
recorded as an event, making it the new value to be com-
pared with.
Demand Interval
Time interval used for the power demand values to be cal-
culated. The values are updated every subinterval.
Demand Subinterval
An interval less than the demand interval, equal to the
demand interval divided by an integer value. Demand cal-
culations are made every subinterval, on the values that
occured during the most recent Demand Interval. Values
become valid after the first Demand Interval has expired.
Fixed Base
A fixed nominal value that is used with the limits in per-
cent.
Floating Base
The nominal value is the average value over the specified
update interval.
Hi Limit
Set point or threshold above the normal range.
Hi-Hi or Very High Limit
Set point or threshold above the high limit.
Instantaneous or Crest Transient
The largest magnitude value in a cycle.
Line-to-Line values for wye circuits
Vab = Van - Vbn; Vbc = Vbn - Vcn; Vca = Vcn - Van
Low Limit
Set point or threshold below the normal range.
Lo-Lo or Very Low Limit
Set point or threshold below the low limit.
Negative Sequence
The three phase vectors that would make a motor rotate
in the reverse direction. U2a = 1/3 (Ua + a
2
*Ub + a*Uc),
where a* is the 120 degree vector operator, a
2
* is the 240
degree vector operator.
Net Current
Vector sum of all phase currents, including neutral
Peak Detected Transient
High frequency deviation from low frequency or normal
sine wave value in either the positive or negative direc-
tion that exceeds programmed limits.
Periodic Reading Interval
Time interval used to periodically record the parameter
for trending or time plots.
Positive Sequence
The three phase vectors that would make a motor rotate
in the positive direction. U1a = 1/3 (Ua + a*Ub + a
2
*Uc),
where a* is the 120 degree vector operator, a
2
* is the 240
degree vector operator.
Power Factor - (true PF)
Watts divided by Volt-amperes on per phase basis (except
delta) and total values.
Reactive Phase Power
Volt ampere reactive power for indiividual phases.
Residual Current
Vector sum of phase currents (not including neutral)
RMS Variation
A change in square root of the sum of samples squared
divided by number of samples (128) that crosses limit
Sequence Imbalance
Negative sequence component divided by positive
sequence.
Total
The phases used in computing the totals depend on the
wiring configuration and parameter. Typically, wye and
delta configurations use the three individual phases,
except for power related, which use the IEEE 1459
equivalent wye method.
