Voltage Protection - ABB REG670 Product Manual

Generator protection REG670 2.2 and Injection equipment REX060,
REX061, REX062
Product version: 2.2.1
side. AEGPVOC is enabled when the terminal voltage drops
below the specified voltage level for the preset time.
Stator overload protection GSPTTR
The generator overload function, (GSPTTR) is used to protect
the stator winding against excessive temperature as a result
of overcurrents. The functions operating characteristic is
designed in accordance with the American standard IEEE-
C50.13.
If internal generator components exceed its design
temperature limit, damage can be the result. Damage to
generator insulation can range from minor loss of life to
complete failure, depending on the severity and duration of
the temperature excursion. Excess temperature can also
cause mechanical damage due to thermal expansion. Since
temperature increases with current, it is logical to apply
overcurrent elements with inverse time characteristics.
For its operation the function either measures the true RMS
current of the stator winding or waited sum of the positive
and negative sequence components in the stator winding.
The function is designed to work on 50/60 Hz systems.
Rotor overload protection GRPTTR
The generator overload function, (GRPTTR) is used to protect
the rotor winding against excessive temperature as a result of
overcurrents. The functions operating characteristic is
designed in accordance with the American standard IEEE-
C50.13.
If internal generator components exceed its design
temperature limit, damage can be the result. Damage to
generator insulation can range from minor loss of life to
complete failure, depending on the severity and duration of
the temperature excursion. Excess temperature can also
cause mechanical damage due to thermal expansion. Rotor
components such as bars and end rings are vulnerable to this
damage. Since temperature increases with current, it is
logical to apply overcurrent elements with inverse time
characteristics.
For its operation the function either measures the true RMS
current of the excitation transformer or calculates the DC
current in the rotor winding. The rotor winding DC current can
be calculated from the AC currents measured on either high
voltage side (HV) or low voltage side (LV) side of the
excitation transformer. For the HV side measurement ratings
of the excitation transformer shall be given. The use of the DC
current is default (i.e. recommended) measurement for
generators with static excitation system. When the DC current
is used, the function can provide a DC current ripple alarm,
due to possible problem with the static excitation equipment.
The rotor DC current can be also sent to the plant supervisory
system via communication channel or displayed on the IED
built-in HMI.
ABB
GUID-A416C856-E438-4ED4-A43D-D05F718D6A41 v6
GUID-E3AE6200-DB8D-4C49-A740-09366A333B4F v5
The function can also detect undercurrent condition in the
rotor winding which indicates either under-excitation or loss
of excitation condition of the generator.
The function is designed to work on 50/60 Hz systems.

7. Voltage protection

Two-step undervoltage protection UV2PTUV
Undervoltages can occur in the power system during faults or
abnormal conditions. The two-step undervoltage protection
function (UV2PTUV) can be used to open circuit breakers to
prepare for system restoration at power outages or as a long-
time delayed back-up to the primary protection.
UV2PTUV has two voltage steps, each with inverse or definite
time delay.
It has a high reset ratio to allow settings close to the system
service voltage.
Two step overvoltage protection OV2PTOV
Overvoltages may occur in the power system during abnormal
conditions such as sudden power loss, tap changer
regulating failures, and open line ends on long lines.
OV2PTOV has two voltage steps, each of them with inverse
or definite time delayed.
OV2PTOV has a high reset ratio to allow settings close to
system service voltage.
Two step residual overvoltage protection ROV2PTOV
Residual voltages may occur in the power system during
earth faults.
Two step residual overvoltage protection (ROV2PTOV)
function calculates the residual voltage from the three-phase
voltage input transformers or measures it from a single
voltage input transformer fed from an open delta or neutral
point voltage transformer.
ROV2PTOV has two voltage steps, each with inverse or
definite time delay.
A reset delay ensures operation for intermittent earth faults.
Overexcitation protection OEXPVPH
When the laminated core of a power transformer or generator
is subjected to a magnetic flux density beyond its design
limits, stray flux will flow into non-laminated components that
are not designed to carry flux. This will cause eddy currents
to flow. These eddy currents can cause excessive heating
and severe damage to insulation and adjacent parts in a
relatively short time. The function has settable inverse
operating curves and independent alarm stages.
Voltage differential protection VDCPTOV
A voltage differential monitoring function is available. It
compares the voltages from two three phase sets of voltage
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