Settings
User’sManual 19
Reactive power and energy calculation
Two different principles of reactive power and energy calculation are used:
Standard method:
With this method a reactive power and energy are calculated based on assumption that all power
(energy) that is not active is reactive.
Q
2
= S
2
– P
2
This means also that all higher harmonics will be measured as reactive power (energy).
Delayed current method:
With this method, reactive power (energy) is calculated by multiplication of voltage samples and
delayed current samples (see chapter Equations on page 53):
Q = U × I|
+90°
With this method, reactive power (energy) represents only true reactive component of apparent
power (energy).
4.5 Connection
Note
Settings of connections shall reflect actual state otherwise measurements
are not valid.
Connection
When connection is selected, load connection and the supported measurements are defined (see
chapter Survey of supported measurements regarding Connection mode on page 27).
Setting of current and voltage ratios
Before setting current and voltage ratios it is necessary to be familiar with the conditions in
which device will be used. All other measurements and calculations depend on these settings. Up
to five decimal places can be set.
Settings range VT primary VT secondary CT primary CT secondary
Maximal value 1638,3 kV 13383 V 1638,3 kA 13383 A
Minimal value 0,1 V 1 mV 0,1 A 1 mA
Used voltage and current range
Setting of the range is connected with all settings of alarms, analog outputs and a display
(calculation) of energy and measurements recording, where 100% represents 500 V 5A. In case
of subsequent change of the range, alarms settings shall be correspondingly changed, as well.
Nominal frequency
A valid frequency measurement is within the range of nominal frequency ±32 Hz. This setting is
used for alarms.
Energy flow direction
This setting allows manual change of energy flow direction (IMPORT to EXPORT or vice versa)
in readings tab. It has no influence on readings sent to communication.
CT connection
If this setting is set to REVERSED it has the same influence as if CT’s would be reversely
connected. All power readings will also change its sign.
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