Positive Sequence Undervoltage Protection Psptuv - ABB REF615 Applications Manual

1MRS756378 D
5.5.5
5.5.5.1
5.5.5.2
5.5.5.3
REF615
Application Manual
This scheme also prevents connecting the machine to the network if the phase
sequence of the network is not correct.
An appropriate value for the setting parameter Voltage start value is approximately
3 percent of U . A suitable value for the setting parameter Operate delay time depends
n
on the application. If the NSPTOV operation is used as backup protection, the operate
time should be set in accordance with the operate time of NSPTOC1 or 2 used as
main protection. If the NSPTOV operation is used as main protection, the operate
time should be approximately one second.

Positive sequence undervoltage protection PSPTUV

Identification
Table 73: Function identification
IEC 61850 identification:
IEC 60617 identification:
ANSI/IEEE C37.2 device number:
Functionality
The positive-sequence undervoltage protection PSPTUV is used to detect positive
phase sequence undervoltage conditions. PSPTUV is used for protection of small
power generation plants. The function helps in isolating an embedded plant from a
fault line when the fault current fed by the plant is too low to start an overcurrent
function but high enough to maintain the arc. Fast isolation of all the fault-current
sources is necessary for a successful autoreclosure from the network-end circuit
breaker.
The function starts when the positive phase sequence voltage goes below the set limit.
PSPTUV operates with the definite time (DT) characteristics.
The function contains a blocking functionality. It is possible to block function outputs,
the definite timer or the function itself, if desired.
Application
PSPTUV is applied for protecting a power station used for embedded generation when
network faults like short circuits or phase-to-earth faults in a transmission or a
distribution line cause a potentially dangerous situations for the power station. A
network fault may be dangerous for the power station for various reasons. The
operation of the protection may cause an islanding condition, also called a loss-of-
mains condition, in which a part of the network, that is, an island fed by the power
station is isolated from the rest of the network. There is then a risk of an autoreclosure
taking place when the voltages of different parts of the network do not synchronize,
which is a straining incident for the power station. Another risk is that the generator
Protection functions
PSPTUV
U1<
47U+
Section 5
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