Measurement During Operation; Description - Siemens SIPROTEC 7SD80 Manual

2.17.3

Measurement During Operation

2.17.3.1 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
rated values of the instrument transformers and the power system as well as the transformation ratio of the
current and voltage transformers in the ground paths.
Display of Measured Values
Operational measured values and metered values are determined in the background by the processor system.
They can be called up on the front of the device, read out via the operator interface using a PC with DIGSI, or
transferred to a control center via the system interface.
Table 2-10 shows a survey of the measured values of the local device. Depending on the version ordered, the
connection of the device, and the configured protection functions, only a part of the listed measured values is
available.
The displacement voltage 3V
3V = |V + V + V
0 A B
The two devices connected via the protection interface(s) form a joint frequency value (constellation frequen-
cy). 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 possible. The constellation frequency is also used
by the differential protection for synchronizing the measured values. Locally operating functions always use the
locally measured frequency.
For the thermal overload protection, the calculated overtemperatures are indicated in relation to the trip over-
temperature. Overload measured values can appear only if the overload protection was configured Enabled.
The power and operating values upon delivery are set such that power in line direction is positive. Active com-
ponents in line direction and inductive reactive components in line direction are also positive. The same applies
for the power factor cosϕ.
It is occasionally desired to define the power drawn from the line (e.g. as seen from the consumer) positively.
Using parameter 1107 P,Q sign the signs for these components can be inverted.
The computation of the operational measured values is also executed during an existent system fault in inter-
vals of approx. 0.5s.
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
is calculated from the connected phase-to-ground voltages
0
|.
C
Functions
2.17 Additional Functions
203