Setting Guidelines - ABB REC650 Applications Manual

Section 7
Voltage protection
7.1.3
7.1.3.1
7.1.3.2
7.1.3.3
152
1. Malfunctioning of a voltage regulator or wrong settings under manual control
(symmetrical voltage decrease).
2. Overload (symmetrical voltage decrease).
3. Short circuits, often as phase-to-ground faults (unsymmetrical voltage decrease).
UV2PTUV (27) prevents sensitive equipment from running under conditions that could
cause their overheating and thus shorten their life time expectancy. In many cases, it is a
useful function in circuits for local or remote automation processes in the power system.

Setting guidelines

All the voltage conditions in the system where UV2PTUV (27) performs its functions
should be considered. The same also applies to the associated equipment, its voltage and
time characteristic.
There is a very wide application area where general undervoltage functions are used. All
voltage related settings are made as a percentage of the global settings base voltage
VBase, which normally is set to the primary rated voltage level (phase-to-phase) of the
power system or the high voltage equipment under consideration.
The setting for UV2PTUV (27) is normally not critical, since there must be enough time
available for the main protection to clear short circuits andground faults.
Some applications and related setting guidelines for the voltage level are described in the
following sections.
Equipment protection, such as for motors and generators
The setting must be below the lowest occurring "normal" voltage and above the lowest
acceptable voltage for the equipment.
Disconnected equipment detection
The setting must be below the lowest occurring "normal" voltage and above the highest
occurring voltage, caused by inductive or capacitive coupling, when the equipment is
disconnected.
Power supply quality
The setting must be below the lowest occurring "normal" voltage and above the lowest
acceptable voltage, due to regulation, good practice or other agreements.
1MRK 511 286-UUS A
Application manual