7SR224 Argus Description of Operation
5.10 Power
Quality
(27S/59S)
Voltage sag (27S) and voltage swell (59S) elements monitor the power supply quality.
The elements monitor the deviation of the voltage from the nominal value and the duration of this under or over
voltage in accordance with IEEE 1159.
Figure 5.10-1 Sag and Swell Indices - IEEE 1159
5.11 Demand
Maximum, minimum and mean values of line currents and voltage (where applicable) are available as instruments
which can be read in the relay INSTRUMENTS MENU or via Reydisp.
The
Gn Demand Log Time Sync
when set as
ENABLED
configures the Demand Log Update Period (see
below) equal to the
DATA STORAGE > Data Log Period
setting.
The
Gn Demand Log Update Period
setting is used to define the time/duration after which the instrument is
updated. The updated value indicates the maximum, minimum and mean values for the defined period. Note that
this setting can be over-ridden by the
Gn Demand Log Time Sync
setting.
The
Gn Demand Window
setting defines the maximum period of time over which the demand values are valid. A
new set of demand values is established after expiry of the set time.
The
Gn Demand Window Type
can be set to
FIXED
or
PEAK
.
When set to
FIXED
the maximum, minimum and mean values demand statistics are calculated over
fixed Window duration. At the end of each window the internal statistics
are reset and a new window is started.
When set to
PEAK
the maximum and minimum values within the
Demand Window
time setting is
recorded.
©2010 Siemens Protection Devices Limited
Chapter 1 Page 64 of 70