Siemens SIPROTEC 4 7UT6 Series Manual page 231

with
P
sec
U
Nprim
U
Nsec
I
Nprim
I
Nsec
P
prim
Example:
Transformer
(Winding)
Current transformer
Voltage transformer
Switching off during P<
Connecting a parallel transformer
Parallel transformer during P>
In case of reference setting (with reference to the sides = winding data)
Address 5112 P< fwd = 0.10
Address 5115 P> fwd = 0.90
When setting in watt secondary, this has the following effect
P< =
P> =
the setting values
Address 5111 Pf< = 80 W
Address 5114 Pf> = 720 W
Delay Times
The setting of the delay times depend on the application. In the example of transformer switchover or also in
case of generator switchover, a long delay (up to one minute = 60 s) will be set so that short-term load fluctu-
ations do not result in repeated switchover. In case of network splitting, short delays are permitted, which,
amongst others, must conform with the time grading of the short-circuit protective relays.
For undershooting of active power, address 5113 T-Pf< applies and for the exceeding of active power
address 5116 T-Pf> applies.
The set times are additional time delays that do not include the operating times (measuring time, dropout
time) of the monitoring function. Please note that averaging over 16 periods is executed during "precise"
measuring procedures; the operating time is thus respectively higher. If a delay time is set to , this does not
result in a trip, however, the pickup will be indicated.
Measuring Procedure
The measuring procedure can be set at address 5117 MEAS. METHOD. This parameter can only be set with
DIGSI under Additional Settings. The option MEAS. METHOD = accurate is mainly required if also small
active power from great apparent power must be calculated precisely, e.g. in generator range or in protected
objects with high reactive power. Please also note that the operating time in this option is higher due to aver-
aging over 16 periods. A precise measurement requires that the angle errors of the current and voltage trans-
formers are compensated by means of a respective setting of the fault angle in address 803 CORRECT. U
SIPROTEC 4, 7UT6x, Manual
C53000-G1176-C230-5, Edition 09.2016
secondary power
primary rated voltage of the voltage transformer (interlinked)
secondary rated current of the voltage transformer (interlinked)
primary rated current of the current transformer
secondary rated current of the current transformer
primary power
16 MVA
20 kV
500 A/5 A
20 kV/100 V
10 % = 0.1
90 % = 0.9
Functions
2.13 Forward Power Supervision
231