Power Quality (27S/59S); Demand; Figure 5.9-1 Sag And Swell Indices - Ieee 1159 - Siemens 7SR224 Description & Operation

(1) Description of Operation 7SR224
5.9 P Q
OWER UALITY
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.
5.10 D
EMAND
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.
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(27S/59S)

Figure 5.9-1 Sag and Swell Indices - IEEE 1159

©2009 Siemens Protection Devices Limited