ABB Relion 670 Series Technical Reference Manual page 169

1MRK 505 208-UEN B
ISI
I3P
IEC06000141 V1 EN
Figure 75: Functional overview of PH4SPTOC
Technical reference manual
Harmonic
Restraint
harmRestrBlock
Element
The sampled analogue phase currents are pre-processed in a discrete Fourier filter
(DFT) block. The RMS value of the phase current is derived. The phase current
value is fed to the PH4SPTOC function. In a comparator the RMS value is
compared to the set operation current value of the function (I1>, I2>, I3> or I4>).
If the phase current is larger than the set operation current a signal from the
comparator is set to true. This signal will, without delay, activate the output signal
Start for this step and a common Start signal.
A harmonic restrain of the function can be chosen. A set 2
relation to the fundamental current is used. The 2
the pre-processing of the phase current and compared to a set restrain current level.
If no blockings are given the start signals will start the timers of the step. The time
characteristic for each step can be chosen as definite time delay or some type of
inverse time characteristic. A wide range of standardized inverse time
characteristics is available. It is also possible to create a tailor made time
characteristic. The possibilities for inverse time characteristics are described in
chapter "Inverse time
Different types of reset time can be selected as described in chapter
characteristics".
There is also a possibility to activate a preset change (IxMult, x= 1, 2, 3 or 4) of the
set operation current via a binary input (enable multiplier). In some applications the
operation value needs to be changed, for example due to changed network
switching state. The function can be blocked from the binary input BLOCK. The
start signals from the function can be blocked from the binary input BLKST. The
trip signals from the function can be blocked from the binary input BLKTR.
One element for each
characteristics".
Current protection
4 step overcurrent
element
step
nd
harmonic current in
nd
harmonic current is taken from
"Inverse time
Section 6
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