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
To Next Page
Loading...
