ABB ret650, Applications Manual

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There are two specific application areas for SAPTUF:
1. to protect equipment against damage due to low frequency, such as generators,
transformers, and motors. Overexcitation is also related to low frequency
2. to protect a power system, or a part of a power system, against breakdown, by
shedding load, in generation deficit situations.
The under frequency start value is set in Hz. All voltage magnitude related settings
are made as a percentage of a global base voltage parameter. The UBase value
should be set as a primary phase-to-phase value.
Some applications and related setting guidelines for the frequency level are given
below:
Equipment protection, such as for motors and generators
The setting has to be well below the lowest occurring "normal" frequency and well
above the lowest acceptable frequency for the equipment.
Power system protection, by load shedding
The setting has to be below the lowest occurring "normal" frequency and well
above the lowest acceptable frequency for power stations, or sensitive loads. The
setting level, the number of levels and the distance between two levels (in time
and/or in frequency) depends very much on the characteristics of the power system
under consideration. The size of the "largest loss of production" compared to "the
size of the power system" is a critical parameter. In large systems, the load
shedding can be set at a fairly high frequency level, and the time delay is normally
not critical. In smaller systems the frequency start level has to be set at a lower
value, and the time delay must be rather short.
The voltage related time delay is used for load shedding. The settings of SAPTUF
could be the same all over the power system. The load shedding is then performed
firstly in areas with low voltage magnitude, which normally are the most
problematic areas, where the load shedding also is most efficient.
9.2 Overfrequency protection SAPTOF
IP15747-1 v3
9.2.1 Identification
M14866-1 v4
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Overfrequency protection SAPTOF
f >
SYMBOL-O V1 EN-US
81
Section 9
1MRK 504 169-UEN A
Frequency protection
164 Transformer protection RET650 2.2 IEC
Application manual