Specifications

PowerLogic:
Glossary of terms
68
Accumulated energy
Energy can accumulate in either signed or unsigned
(absolute) mode. In signed mode, the direction of power
flow is considered and the accumulated energy
magnitude may increase and decrease. In absolute
mode, energy accumulates as a positive regardless of
the power flow direction.
Active (or real or Resistive) current and power
Only the component of the current that is in-phase with
the voltage can be used to supply real energy e.g. heat
or mechanical work. This component is produced by the
resistance of the load.
Active Power (W) = Voltage (V) x In-phase Current (A).
ANSI
American National Standards Institute.
Baud rate
Specifies how fast data is transmitted across a network
point.
Billing point (Billing date)
A billing action can occur on a billing date. Billing dates
can be hard coded or can be programmed by a tariff
(see below). The billing action occurs just after midnight
on the billing date i.e. at the start of the day, not the end.
Block interval demand
Power demand calculation method for a block of time
and includes three ways to apply calculating to that
block of time using the sliding block, fixed block or
rolling block method.
Circuit monitor
An advanced power metering and analysis instrument.
Conditional energy
Energy accumulates only when a certain condition
occurs.
Crest factor (CF)
Crest factor of voltage or current is the ratio of peak
values to rms values.
Cumulative maximum demand
In order to help detect any attempt at fraud, when an MD
reset occurs the values in one or more MD registers are
added into a cumulative MD register. The supplier should
then be able to detect an unexpected (and possibly
fraudulent) MD reset by an unexpected increase in the
cumulative value.
Current transformer (CT)
A transformer used to convert a current in a circuit to a
measureable value, usually 5A or 1A. Special precautions
must be taken when connecting and disconnecting these
devices.
Current unbalance
Percentage difference between each phase voltage with
respect to the average of all phase currents.
Demand
Average value of a quantity, such as power, over a
specified interval of time.
Device address
Defines where the circuit monitor (or other devices)
reside in the power monitoring system.
Displacement power factor (dPF)
Cosine of the angle between the fundamental
components of current and voltage, which represents the
time lag between fundamental voltage and current.
Ethernet
Media for fast, cost effective open networking.
Ethernet address
A unique number that identifies the device in the
Ethernet network and is always written as a combination
of eleven or twelve numbers such as 199.186.195.23.
Event
The occurrence of a condition such as an alarm.
Fundamental (a term used in harmonic analysis)
Value of voltage or current corresponding to the portion
of the signal at the supply frequency (50, 60 or 400Hz).
Harmonic
An integer multiple of the fundamental frequency in an
a.c. network.
Harmonic power
Difference between total power and fundamental power.
A negative value indicates harmonic power flow out of
the load. A positive value indicates harmonic power flow
into the load.
IEC
International Electrotechnical Commission.
Import, Export
Changing the phase angle of a current by 180 degrees is
equivalent to negating its value. It is therefore possible to
consider a current to be positive or negative depending
on its phase angle. A positive current is said to be
importing or consuming power and a negative current is
exporting or generating power.
Incremental energy
Accumulates energy during a user-defined timed interval.
K-Factor
This relates the heating effect of a distorted current in a
transformer to a sinusoidal current with the same r.m.s
magnitude.
Lag and lead
The current is "lagging" behind the voltage when the
power factor is positive. i.e. when the phase angle is 0
degrees to 90 degrees or 180 degrees to 270 degrees. At
other phase angles the power factor is negative and the
current is "leading" the voltage.
Logging
Recording data at user-defined intervals in the meter’s
nonvolatile memory.
Maximum demand
Electricity bills frequently have a component, which
depends on the maximum demand over the billing period
(typically a month). A maximum demand register records
the maximum value of demand over the billing period. A
meter may have more than one maximum demand
register: each register will be "active" at particular times
of the day, or when a particular rate register is active.
Maximum demand reset
At the end of a billing period the maximum demand
registers are reset to zero so that they can start
recording another maximum in the new billing period.
Maximum value
Highest value recorded of an instantaneous quantity
since the last reset of the minimum and maximum.
Minimum value
Lowest value recorded of an instantaneous quantity
since the last reset of the minimum and maximum.
Modbus
Industrial standard serial communications protocol.
Overvoltage
Increase in effective voltage to greater than 100 percent
for longer than one minute. See also voltage swell.