Siemens siprotec 7SD5 User Manual

2.24 Ancillary Functions
423
7SD5 Manual
C53000-G1176-C169-1
2.24.4 Measurement During Operation
2.24.4.1 Functional Description
A series of measured values and the values derived from them are available for on-
site retrieval or for data transfer.
A precondition for a correct display of primary and percentage values is the complete
and correct entry of the nominal values of the instrument transformers and the power
system as well as the transformation ratio of the current and voltage transformers in
the earth paths.
Display and Trans-
mission of Mea-
sured Values
Operational measured values and metered values are determined in the background
by the processor system. They can be called up at the front of the device, read out via
the operator interface using a PC with DIGSI
®
, or transferred to a central master
station via the system interface.
Depending on the ordering code, connection type to the device and the configured
protection function, only some of the listed operational measured values in Table 2-20
may be available. Of the current values I
EE
, I
Y
and I
P
only the one which is connected
to the current measuring input I
4
can apply. Phase-to-earth voltages can only be mea-
sured if the phase-to-earth voltage inputs are connected. The displacement voltage
3U
0
is e-n-voltage multiplied by √3 — if U
en
is connected — or calculated from the
phase-to-earth voltages 3U
0
=|U
L1
+U
L2
+U
L3
|. All three voltage inputs must be
phase-earth connected for this.
If multiple devices are interconnected via their protection data interfaces, a common
frequency value is calculated across the whole constellation (constellation frequency).
This value is displayed as the operational measured value „Frequency“. It allows to
display a frequency even in devices in which local frequency measurement is not pos-
sible. The constellation frequency is also used by the differential protection for syn-
chronizing the measured values. Locally operating functions such as frequency pro-
tection always use the locally measured frequency.
If the device operates in a local mode (device is logged off, in test mode, or protection
data interface is not connected), the locally measured frequency is displayed.
For the thermal overload protection, the calculated overtemperatures are indicated in
relation to the trip overtemperature. Overload measured values can appear only if the
overload protection was configured Enabled.
If the device features a synchronism and voltage check function, and provided that
these features have been set to 135 during configuration of the scope of the device
(address Enabled), and that the parameter U4 transformer (address 210) has
been set to Usync transf., the characteristic values (voltages, frequencies, differ-
ences) can be read out.
The power components P, Q are positive, when real power or inductive reactive power
are flowing into the protected object, assuming that this direction has been parameter-
ized as forward.
The sign of the power factor cos ϕ corresponds to the sign of the real power.
The operational measured values are also calculated in the event of a running fault in
intervals of approximately 0.5 s.
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Siemens siprotec 7SD5 Specifications

General

Brand	Siemens
Model	siprotec 7SD5
Category	Relays
Language	English