
transformer cores with the neutral point current on a
separate input taken from another set of cores on the
current transformer.
A detection of a difference indicates a fault in the circuit
and is used as alarm or to block protection functions
expected to give inadvertent tripping.
Fuse failure supervision FUFSPVC
SEMOD113820-4 v11
The aim of the fuse failure supervision function
FUFSPVC is to block voltage measuring functions at
failures in the secondary circuits between the voltage
transformer and the IED in order to avoid inadvertent
operations that otherwise might occur.
The fuse failure supervision function basically has three
different detection methods, negative sequence and
zero sequence based detection and an additional delta
voltage and delta current detection.
The negative sequence detection algorithm is
recommended for IEDs used in isolated or high-
impedance earthed networks. It is based on the
negative-sequence quantities.
The zero sequence detection is recommended for IEDs
used in directly or low impedance earthed networks. It is
based on the zero sequence measuring quantities.
The selection of different operation modes is possible
by a setting parameter in order to take into account the
particular earthing of the network.
A criterion based on delta current and delta voltage
measurements can be added to the fuse failure
supervision function in order to detect a three phase
fuse failure, which in practice is more associated with
voltage transformer switching during station
operations.
Fuse failure supervision VDSPVC
GUID-6AF2219A-264F-4971-8D03-3B8A9D0CB284 v4
Different protection functions within the protection IED
operates on the basis of measured voltage at the relay
point. Some example of protection functions are:
• Distance protection function.
• Undervoltage function.
• Energisation function and voltage check for the weak
infeed logic.
These functions can operate unintentionally, if a fault
occurs in the secondary circuits between voltage
instrument transformers and the IED. These
unintentional operations can be prevented by VDSPVC.
VDSPVC is designed to detect fuse failures or faults in
voltage measurement circuit, based on phase wise
comparison of voltages of main and pilot fused circuits.
VDSPVC blocking output can be configured to block
functions that need to be blocked in case of faults in the
voltage circuit.
Multipurpose filter SMAIHPAC
GUID-EB0B11C3-FF79-4B8D-A335-649623E832F9 v2
The multi-purpose filter function block, SMAIHPAC, is
arranged as a three-phase filter. It has very much the
same user interface (e.g. inputs and outputs) as the
standard pre-processing function block SMAI. However
the main difference is that it can be used to extract any
frequency component from the input signal. Thus it can,
for example, be used to build sub-synchronous
resonance protection for synchronous generator.
10. Control
Synchrocheck, energizing check, and synchronizing
SESRSYN
M12480-3 v15
The Synchronizing function allows closing of
asynchronous networks at the correct moment including
the breaker closing time, which improves the network
stability.
Synchrocheck, energizing check, and synchronizing
SESRSYN function checks that the voltages on both
sides of the circuit breaker are in synchronism, or with
at least one side dead to ensure that closing can be
done safely.
SESRSYN function includes a built-in voltage selection
scheme for double bus and 1½ breaker or ring busbar
arrangements.
Manual closing as well as automatic reclosing can be
checked by the function and can have different settings.
For systems, which are running asynchronous, a
synchronizing function is provided. The main purpose of
the synchronizing function is to provide controlled
closing of circuit breakers when two asynchronous
systems are going to be connected. The synchronizing
function evaluates voltage difference, phase angle
difference, slip frequency and frequency rate of change
before issuing a controlled closing of the circuit breaker.
Breaker closing time is a parameter setting.
Apparatus control APC
M13444-3 v13
The apparatus control functions are used for control and
supervision of circuit breakers, disconnectors and
earthing switches within a bay. Permission to operate is
given after evaluation of conditions from other
functions such as interlocking, synchrocheck, operator
place selection and external or internal blockings.
Apparatus control features:
• Select-Execute principle to give high reliability
• Selection function to prevent simultaneous operation
• Selection and supervision of operator place
1MRK 504 155-BEN F
Transformer protection RET670 2.1 IEC
36
ABB
Содержание Relion 670 series
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