Siemens SIPROTEC 7UT613 series Manual page 22

1 Introduction
22
at the ends of the protected zone feed a common (external) high-ohmic resistor The
current in this resistor is measured using a high-sensitive current input 7UT613/63x.
The device provides backup time overcurrent protection functions for all types of pro-
tected objects. The functions can be enabled for any side or measuring location.
A thermal overload protection function is available for any type of machine. The func-
tions can be enabled for any side. External detectors account for the coolant temper-
ature (by means of an external RTD-box). This allows to calculate and output the hot-
spot temperature and the relative ageing rate.
An unbalanced load protection function is provided for the detection of unsymmetrical
currents. Phase failures and negative sequence currents, which are especially dan-
gerous for rotating machines, can thus be detected.
Performance functions allow devices with voltage measuring inputs to implement a
reverse power protection or monitor the forward power supply(in the power station
sector). In the system they can be used for network decoupling. Power results and
their components can be emitted as measured values.
The versions with voltage inputs are provided with an integrated overexcitation protec-
tion for the detection of excessive induction states in shunt reactions (transformers,
shunt reactors). This protection function monitors the ratio U/f, which is proportional to
the induction B in the iron core. An imminent iron core saturation, which can occur es-
pecially in power stations following (full) load shutdown and/or frequency reduction, is
thus detected.
An undervoltage and overvoltage protection is to be integrated into devices with
voltage measuring inputs. A 4-stage frequency protection monitors the frequency from
the measured voltages.
A version for two-phase application is available for traction supply (transformers or
generators) which provides all functions suited for this application (differential protec-
tion, restricted earth fault protection, overcurrent protection, overload protection).
With 7UT613/63x two circuit-breaker failure protection functions can be realised. A
circuit-breaker failure protection checks the reaction of one circuit breaker after a trip
command. It can be assigned to any of the sides of a protected object.
More protection, supervision and measuring functions can be configured with flexible
functions. Up to 12 of these functions can be specified; the measured quantities you
want to process and which reactions the device is to trigger when under/overshooting
adjustable limit values. With that you can create time overcurrent protection and
process voltages, power or symmetrical components of measured quantities.
One can configure the calculation of minimum, maximum and/or average values
and/or minimum, maximum of the average values of up to 20 selectable measured
quantities, thus receiving one's own statistical data.
7UT613/63x Manual
C53000-G1176-C160-2