Siemens siprotec 7SA522 User Manual

2.1 General
41
7SA522 Manual
C53000-G1176-C155-3
Voltage Connection The device features four voltage measuring inputs, three of which are connected to
the set of voltage transformers. Various possibilities exist for the fourth voltage input
U
4
:
• Connect the U
4
input to the open delta winding e–n of the voltage transformer set:
Address  is then set to: 8WUDQVIRUPHU = 8GHOWDWUDQVI.
When connected to the e-n winding of a set of voltage transformers, the voltage
transformation ratio of the voltage transformers is usually:
The factor Uph/Udelta (secondary voltage, address  8SK8GHOWD) must be
set to 3/√3
= √3 ≈ 1.73 . For other transformation ratios, i.e. the formation of the dis-
placement voltage via an interconnected transformer set, the factor must be cor-
rected accordingly. This factor is of importance if the 3U
0
>-protective element is
used and for the monitoring of the measured values and the scaling of the measure-
ment and disturbance recording signals.
• Connection of the U
4
input to the busbar voltage in order to perform the synchro-
nism check:
Address  is then set to: 8WUDQVIRUPHU = 8V\QFWUDQVI.
If the transformation ratio differs from that of the line voltage transformers, this can
be adapted with the setting in address  8OLQH8V\QF. In address 
8V\QFFRQQHFW, the busbar voltage used for synchronism check is configured.
The device then selects automatically the appropriate feeder voltage. If the two
measuring points used for synchronism check — i.e. feeder voltage transformer
and busbar voltage transformer — are not separated by devices that cause a rela-
tive phase shift, then the parameter in address  ϕ8V\QF8OLQH is not re-
quired. This setting is only possible via DIGSI
®
at "Additional Settings". If however
a power transformer is switched in between, its vector group must be considered.
The phase angle from U
line
to U
2bus
is evaluated positively.
Example
: (see also Figure 2-3)
Busbar 400 kV primary,
110 V secondary,
Feeder 220 kV primary,
100 V secondary,
Transformer 400 kV/220°kV,
Vector group Yd(n) 5
The transformer vector group is defined from the high side to the low side. In this
example, the feeder voltage is connected to the low voltage side of the transformer.
If Usync (busbar or high voltage side) is placed at zero degrees, then Uline is at 5
x 30° (according to the vector group) in the clockwise direction, i.e. at –150°. A pos-
itive angle is obtained by adding 360°:
Address : ϕ8V\QF8OLQH = 360° - 150° = 210°.
The busbar transformers supply 110 V secondary for primary operation at nominal
value while the feeder transformer supplies 100 V secondary. Therefore, this differ-
ence must be balanced:
Address : 8OLQH8V\QF = 100 V/110 V = 0.91.

Siemens siprotec 7SA522 Specifications

General

Brand	Siemens
Model	siprotec 7SA522
Category	Protection Device
Language	English