Siemens SIPROTEC 7UT613 series Manual page 19

Microcomputer
system
7UT613/63x Manual
C53000-G1176-C160-2
and earth, or other single-phase measuring currents. One or two additional inputs can
be designed for highly sensitive current detection, This, for example, allows the detec-
tion of small tank leakage currents of power transformers or - with an external series
resistor - the detection of a voltage (e.g. for high-impedance unit protection).
The versions 7UT613 and 7UT633 can be ordered with 4 additional voltage inputs. 3
of these inputs can be connected to the phase-to-earth voltages. Another voltage input
can be used for a single-phase voltage, such as a displacement voltage or any other
voltage. In principle, the differential protection is designed such that it can operate
without measured voltages. However, the integrated overexcitation protection uses
the measuring voltage to calculate the induction in transformers or shunt reactors. In
addition, the measuring voltages and the quantities derived from them (induction,
power, power factor) can be displayed, annunciated and/or monitored by the device if
the voltages are connected.
The analogue signals are then routed to the input amplifier group "IA".
The input amplifier group IA provides high-resistance termination for the analogue
input quantities and contains filters that are optimised for measured value processing
with regard to bandwidth and processing speed.
The analogue-to-digital (AD) stage consists of a multiplexor, an analogue-to-digital
(A/D) converter and memory components for the transmission of digital signals to the
microcomputer system.
In addition to the control of the measured values, the actual protection and control
functions are processed in the µC microcomputer system. In particular, the following
is included:
• filtering and conditioning of measured signals
• continuous monitoring of measured signals
• monitoring of the pickup conditions of the individual protective functions
• Conditioning of the measured signals: i.e. conversion of currents according to the
connection group of the protected transformer (when used for transformer differen-
tial protection) and matching of the current amplitudes.
• formation of the differential and restraint quantities
• calculation of the RMS values of the currents for overload detection and adjustment
of the temperature rise of the protected object
• retrieval of threshold values and time sequences
• processing of signals for the logic functions
• Processing User-defined Logic Functions
• reaching trip command decisions
• Check of control commands and output to switching devices
• storage of indications, fault data and fault values for fault analysis purposes
• Calculation and display/annunciation of measured values and the quantities
derived from them
• management of the operating system and its functions, e.g. data storage, real-time
clock, communication, interfaces, etc.
The information is provided via output amplifier OA.
1.1 Overall Operation
19