• Definite time delay or Inverse Time Overcurrent TOC/IDMT delay for both
steps
• Second harmonic supervision is available in order to only allow operation of
the overcurrent stage(s) if the content of the second harmonic in the
measured current is lower than pre-set level
•
Directional supervision is available in order to only allow operation of the
overcurrent stage(s) if the fault location is in the pre-set direction (Forward
or Reverse). Its behavior during low-level polarizing voltage is settable
(Non-Directional,Block,Memory)
• Voltage restrained/controlled feature is available in order to modify the pick-
up level of the overcurrent stage(s) in proportion to the magnitude of the
measured voltage
• Current restrained feature is available in order to only allow operation of the
overcurrent stage(s) if the measured current quantity is bigger than the set
percentage of the current restrain quantity.
2. Two undercurrent steps with the following built-in features:
• Definite time delay for both steps
3. Two overvoltage steps with the following built-in features
• Definite time delay or Inverse Time Overcurrent TOC/IDMT delay for both
steps
4. Two undervoltage steps with the following built-in features
• Definite time delay or Inverse Time Overcurrent TOC/IDMT delay for both
steps
All these four protection elements within one general protection function works
independently from each other and they can be individually enabled or disabled.
However it shall be once more noted that all these four protection elements measure
one selected current quantity and one selected voltage quantity (see table
49 and
table 50). It is possible to simultaneously use all four-protection elements and their
individual stages. Sometimes in order to obtain desired application functionality it is
necessary to provide interaction between two or more protection elements/stages
within one CVGAPC function by appropriate IED configuration (for example, dead
machine protection for generators).
12.1.2.1
Current and voltage selection for CVGAPC function
SEMOD53443-6 v3
CVGAPC function is always connected to three-phase current and three-phase voltage
input in the configuration tool, but it will always measure only the single current and
the single voltage quantity selected by the end user in the setting tool (selected current
quantity and selected voltage quantity).
Section 12 1MRK 504 163-UUS A
Multipurpose protection
644 Transformer protection RET670 2.2 ANSI
Application manual
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