Underfrequency Protection Saptuf; General Current And Voltage Protection Cvgapc; Overfrequency Protection Saptof; Loss Of Voltage Check Lovptuv - ABB RET670 Product Manual

Transformer protection RET670 2.0
Product version: 2.0
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
transformers and has one sensitive alarm step and one trip
step.

Loss of voltage check LOVPTUV

Loss of voltage check LOVPTUV is suitable for use in networks
with an automatic system restoration function. LOVPTUV
issues a three-pole trip command to the circuit breaker, if all
three phase voltages fall below the set value for a time longer
than the set time and the circuit breaker remains closed.
The operation of LOVPTUV is supervised by the fuse failure
supervision FUFSPVC.
7. Frequency protection

Underfrequency protection SAPTUF

Underfrequency occurs as a result of a lack of generation in the
network.
Underfrequency protection SAPTUF measures frequency with
high accuracy, and is used for load shedding systems, remedial
action schemes, gas turbine startup and so on. Separate
definite time delays are provided for operate and restore.
SAPTUF is provided with undervoltage blocking.
The operation is based on positive sequence voltage
measurement and requires two phase-phase or three phase-
neutral voltages to be connected. For information about how to
connect analog inputs, refer to Application manual/IED
application/Analog inputs/Setting guidelines

Overfrequency protection SAPTOF

Overfrequency protection function SAPTOF is applicable in all
situations, where reliable detection of high fundamental power
system frequency is needed.
Overfrequency occurs because of sudden load drops or shunt
faults in the power network. Close to the generating plant,
generator governor problems can also cause over frequency.
SAPTOF measures frequency with high accuracy, and is used
mainly for generation shedding and remedial action schemes. It
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is also used as a frequency stage initiating load restoring. A
definite time delay is provided for operate.
SAPTOF is provided with an undervoltage blocking.
The operation is based on positive sequence voltage
measurement and requires two phase-phase or three phase-
neutral voltages to be connected. For information about how to
connect analog inputs, refer to Application manual/IED
application/Analog inputs/Setting guidelines
Rate-of-change frequency protection SAPFRC
The rate-of-change frequency protection function SAPFRC
gives an early indication of a main disturbance in the system.
SAPFRC measures frequency with high accuracy, and can be
used for generation shedding, load shedding and remedial
action schemes. SAPFRC can discriminate between a positive
or negative change of frequency. A definite time delay is
provided for operate.
SAPFRC is provided with an undervoltage blocking. The
operation is based on positive sequence voltage measurement
and requires two phase-phase or three phase-neutral voltages
to be connected. For information about how to connect analog
inputs, refer to Application manual/IED application/Analog
inputs/Setting guidelines.
8. Multipurpose protection

General current and voltage protection CVGAPC

The protection module is recommended as a general backup
protection with many possible application areas due to its
flexible measuring and setting facilities.
The built-in overcurrent protection feature has two settable
current levels. Both of them can be used either with definite
time or inverse time characteristic. The overcurrent protection
steps can be made directional with selectable voltage polarizing
quantity. Additionally they can be voltage and/or current
controlled/restrained. 2nd harmonic restraining facility is
available as well. At too low polarizing voltage the overcurrent
feature can be either blocked, made non directional or ordered
to use voltage memory in accordance with a parameter setting.
Additionally two overvoltage and two undervoltage steps, either
with definite time or inverse time characteristic, are available
within each function.
The general function suits applications with underimpedance
and voltage controlled overcurrent solutions. The general
function can also be utilized for generator transformer
protection applications where positive, negative or zero
sequence components of current and voltage quantities are
typically required.
1MRK 504 141-BEN C
ABB