Siemens 7UT51 User Manual

4
Transformer Differential Protection (87T and 87HS)
7UT51 v3
44 PRIM-2330C
4.2.1 Type of Transformer
The relay uses different addresses and algorithms for
different types of protected objects. Address 7801
specifies what type of device or equipment is being
protected.
Model 7UT513 is required if the protected transformer
has three windings, or if the application includes
measurement of a ground (or neutral) current. A
7UT513 can also be used to simultaneously protect
both a two-winding transformer and an additional
protected device.
4.2.2 Normal Operational Status
The differential functions (87 and 87HS) can be set
either to exist or not to exist in Address 7816.
Functions that are configured as NONEXISTENT (or
DISABLED) will not process annunciations and the
associated setting parameters will not be requested
during setting.
Once the 87T and 87HS functions exist, they can be
configured. Additionally, Address 7801 must be set as
a transformer. The function’s operational status is set
in Address 1601. If the status is set to OFF, it will have
no effect on the result of the protective process;
therefore, no tripping is initiated. If BLOCK TRIPPING
is chosen, all functions are active except the trip
contacts and signal contacts; therefore, no tripping is
initiated
Note that the default setting is OFF. Without correct
parameter settings the relay may show unexpected
reactions which include false tripping.
4.2.3 System Frequency
The rated nominal frequency of the protected
transformer is specified in Address 7899.
Note:
The choice of frequency affects the availability
the auxiliary protection functions. With rated
frequency 60Hz, the backup overcurrent time
protection or the restricted earth fault
protection/tank leakage protection (dependent
on the ordered model) can be used besides the
differential protection for transformers. If the
three-winding transformer protection is to be
used, only the backup overcurrent time
protection is available.
With rated frequency 50Hz, the backup overcurrent
time protection or the restricted earth fault protection/
tank leakage protection (dependent on the ordered
model) can be used in addition to differential
protection for transformers.
With rated frequency 16 2/3 Hz, no restriction
concerning the additional functions are present.
If, during configuration, more functions have been
selected than the device is able to process, the relays
will give a corresponding message after configuration
has been finished. These messages can be read out
in the operational annunciations.
7801 PROT.OBJ
Type of device or equipment the relay is protecting.
Option Description
2
-
WIND
-
TRANSF
two
-
winding transformer (default)
3
-
WIND
-
TRANSF
three
-
winding transformer
(7UT513 only)
MOTOR/GENERA-
TOR
motor or generator (see Chapter 5)
2 ENDED TIE PT.
two
-
branch bus (see Chapter 6)
3 ENDEDTIE PT.
three
-
branch bus (see Chapter 6)
1Ph.
-
TRANSF
single
-
phase transformer
7816 87 STATUS
Choice of whether transformer differential
protection functions (87T and 87HS) exist.
Option Description
EXISTENT/
ENABLED
87T and 87HS functions
exist (default).
NONEXISTENT/
DISABLED
87T and 87HS functions do
not exist.
1601 87 STATUS
Operational status of transformer differential protection
(87T and 87HS).
Option Description
OFF
87T and 87HS functions are inactive (default).
ON
87T and 87HS functions are active.
BLOCK
TRIPPING
87T and 87HS functions are active except that
trip contacts and signal contacts will not
respond to 87T and 87HS events.
7899 FREQUENCY
Rated nominal frequency of the protected transformer.
Option Description
FREQ 50 Hz
50 Hertz
FREQ 60 Hz
60 Hertz (default)
FREQ 16 2/3 Hz
16
-
2/3 Hertz

Siemens 7UT51 Specifications

General

Brand	Siemens
Model	7UT51
Category	Relays
Language	English