ABB RELION REX640 Technical Manual page 331

1MRS759142 F
Table 365: Reset time characteristics supported by different stages
Reset curve type
(1) Immediate
(2) Def time reset
(3) Inverse reset
4.1.1.8 Application
PHxPTOC is used in several applications in the power system. The applications
include but are not limited to:
• Selective overcurrent and short-circuit protection of feeders in distribution and
subtransmission systems
• Backup overcurrent and short-circuit protection of power transformers and
generators
• Overcurrent and short-circuit protection of various devices connected to the
power system, for example shunt capacitor banks, shunt reactors and motors
• General backup protection
PHxPTOC is used for single-phase, two-phase and three-phase non-directional
overcurrent and short-circuit protection. Typically, overcurrent protection is used
for clearing two and three-phase short circuits. Therefore, the user can choose how
many phases, at minimum, must have currents above the start level for the function
to operate. When the number of start-phase settings is set to "1 out of 3", the
operation of PHxPTOC is enabled with the presence of high current in one-phase.
Many applications require several steps using different current start levels and time
delays. PHxPTOC consists of three protection stages.
• Low PHLPTOC
• High PHHPTOC
• Instantaneous PHIPTOC
PHLPTOC is used for overcurrent protection. The function contains several types of
time-delay characteristics. PHHPTOC and PHIPTOC are used for fast clearance of
very high overcurrent situations.
REX640
Technical Manual
PHIPTOC supports only definite time characteristic.
For a detailed description of timers, see
block features
in this manual.
PHLPTOC
x
x
x
Type of reset curve setting does not apply to PHIPTOC or when the
The
DT operation is selected. The reset is purely defined by the
time setting.
When the setting is "2 out of 3" or "3 out of 3", single-phase faults are not
detected. The setting "3 out of 3" requires the fault to be present in all
three phases.
Chapter 11 General function
PHHPTOC Note
x Available for all operate time curves
x Available for all operate time curves
x Available only for ANSI and user pro-
grammable curves
Protection functions
Reset delay
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