Siemens siprotec 7SA522 User Manual

2 Functions
166
7SA522 Manual
C53000-G1176-C155-3
([WUHPHO\,QY,
'HILQLWH,QY.
The characteristics and equations they are based on are listed in the Technical Data.
The setting of the pickup threshold ,S3,&.83 (address ) is similar to the
setting of definite time stages (see above). In this case it must be noted that a safety
margin between the pickup threshold and the set value has already been incorporat-
ed. Pickup only occurs at a current which is approximately 10 % above the set value.
The time multiplier setting ,S7LPH'LDO (address ) is derived from the
grading coordination chart which was set up for earth faults in the system.
In addition to the inverse time delay, a constant (fixed length) time delay can also be
set if this is required. The setting $GG7'(/$< (address ) is added to the time
of the set curve.
During the selection of the current and time settings, regard must be taken as to
whether a stage should be direction dependent and whether it uses teleprotection.
Refer also to the margin headings “Determination of Direction” and “Teleprotection
with Earth Fault Protection”.
Inverse Time Stage
with Logarithmic
Inverse
Characteristic
If you have configured the inverse time overcurrent stage with logarithmic inverse
characteristic (address  (DUWK)DXOW2& = 72&/RJDULWKP), the operating
mode is initially set:: address  2SPRGH,S. The stage can be set to operate
)RUZDUG (usually towards line), 5HYHUVH (usually towards busbar) or 1RQ
'LUHFWLRQDO (in both directions). If the stage is not required, set its mode to
,QDFWLYH.
For the logarithmic inverse characteristic (address  (DUWK)DXOW2& = 72&
/RJDULWKP) the setting of address is  $16,&XUYH = /RJLQYHUVH.
The characteristics and equations they are based on are listed in the Technical Data.
Figure 2-72 illustrates the influence of the most important setting parameters on the
curve. ,S3,&.83 (address ) is the reference value for all current values,
while ,S6WDUWSRLQW (address ) determines the beginning of the curve, i.e.
the lowest operating range on the current axis (referred to ,S3,&.83). The timer
setting ,S0D[7'(/$< (address ) determines the starting point of the curve
(for 3I
0
= ,S3,&.83). The time factor ,S7LPH'LDO (address ) changes
the slope of the curve. For large currents, ,S0LQ7'(/$< (address ) deter-
mines the lower limit on the time axis. For currents larger than 30 · ,S3,&.83 the
operating time no longer decreases.
Finally in address  $GG7'(/$< a fixed time delay can be set as was done for
other curves.
During the selection of the current and time settings, regard must be taken as to
whether a stage should be direction dependent and whether it uses teleprotection.
Refer also to the margin headings “Determination of Direction” and “Teleprotection
with Earth Fault Protection”.

Siemens siprotec 7SA522 Specifications

General

Brand	Siemens
Model	siprotec 7SA522
Category	Protection Device
Language	English