Table 1. Supported functions, continued
Functionality
CTs & VTs
Generic up-down counters, instance 7
●
Generic up-down counters, instance 8
●
Generic up-down counters, instance 9
●
Generic up-down counters, instance 10
●
Generic up-down counters, instance 11
●
Generic up-down counters, instance 12
●
Programmable buttons (16 buttons)
●
Logging functions
Disturbance recorder
●
Fault recorder
●
Sequence event recorder
●
Load profile
●
● = Included,○ = Optional at the time of the order
1)
The function is to be used on high voltage winding side in the application
2)
The function is to be used on low voltage winding side in the application
3)
The function is to be used on high voltage winding side in the application,and uses calculated Io when HREF and varistor connection used
4)
The function is to be used on low voltage winding side in the applicationand,and uses calculated Io when HREF and varistor connection used
5)
Calculated Io is used for the residual current criteria
3. Protections functions
The IED features a three-phase, multi-slope stabilized (biased)
stage transformer differential protection and an instantaneous
stage to provide fast and selective protection for phase-to-
phase short circuit, winding interturn fault and bushing flash-
over protection. Besides the second harmonic restraint, an
advanced waveform-based blocking algorithm ensures
stability at transformer energization and the fifth harmonic
restraint function ensures good protection stability at
moderate overexcitation of power transformers. The restricted
earth-fault protection (REF) completes the overall differential
protection providing detection of even single phase-to-earth
faults close to the neutral earthing point of the transformer.
Either the conventional high-impedance scheme or the
numerical low-impedance scheme can be selected for
protection of the transformer windings. When the low-
impedance REF protection is used, neither stabilizing
resistors nor varistors are needed and, as a further benefit,
the transforming ratio of the neutral earthing CTs can differ
from that of the phase current transformers. Due to its unit
protection character and absolute selectivity, REF does not
need to be time-graded with other protection schemes, and
therefore a high-speed fault clearance can be achieved.
The IED also incorporates a thermal overload protection
function that supervises the thermal stress of the transformer
windings to prevent the premature aging of the insulation of
the windings. Multiple stages of short circuit, phase-
overcurrent, negative-phase-sequence and earth-fault backup
protection are separately available for both sides of the power
transformer. An earth-fault protection based on the measured
or calculated residual voltage is also available. The IED also
features three-phase overvoltage protection, three-phase
undervoltage protection and residual overvoltage protection.
Furthermore, the IED also offers circuit breaker failure
protection.
Enhanced with optional hardware and software, the IED also
features three light detection point-to-point lens sensors for
arc fault protection of the circuit breaker, busbar and cable
compartment of metal-enclosed indoor switchgear.
The arc fault protection sensor interface is available on the
optional communication module. Fast tripping increases staff
safety and security and limits material damage in an arc fault
situation. Optional high speed outputs help to minimize the
arc impacts.
Transformer Protection and Control
1MRS757846 A
RET620
Product version: 2.0
ABB
9
Содержание RET620
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