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REB500 bay protection (optional)

The system provides an option to extend the functional scope of REB500 by a set of predefined bay protection

functions used as main 2 or back-up line protection.

Version ‘Line variant L-V2’ includes distance, directional/non directional overcurrent and directional earthfault protection functions (see Table 2).

As regards the level of voltages and frequencies busbar and station protection have the same application area.

For details on application and technical data refer to the REB500 Application Manual for bay protection functions.

Main features

Low-impedance busbar protection

· High functional reliability due to two independent measurement criteria:

– stabilized differential current algorithm

– directional current comparison algorithm

· Short tripping times independent of the plant’s size or busbar configuration

· Phase Segregated measurement

· Stub and T-zone protection

· Reduced CT performance requirements

– High through-fault stability even in case of CT saturation

– No switching of CT circuits

Application

REB500

The numerical busbar protection REB500 is designed for the high-speed (sub-cycle), selective protection of MV, HV

and EHV busbar installations at a nominal frequency of 50, 60 Hz The modular system structure is enabling the protection to

be easily configured to suit the layout of the primary system.

The flexibility of the system enables all configurations of busbars from single to quadruple, with transfer buses or

ring busbars and 1½ breaker schemes to be protected.

In 1½ breaker schemes the busbars and entire diameters, including Stub/T-Zone can be protected. 

An integrated tripping scheme allows saving external logics as well as wiring.

The system is scalable for up to 60 feeders (bay units) and a total of 32 busbar zones.

The numerical busbar protection REB500 detects all phase and earth faults in solidly grounded and resistivegrounded power systems and phase faults in ungrounded

systems and systems with Petersen coils.

The main CTs supplying the currents to the busbar protection have to fulfill only modest performance

requirements (see page 17). The protection operates discriminatively for all faults inside the zone of protection

and remains reliably stable for all faults outside the zone of protection.

The differential function offers a high sensitivity for low-level internal faults.

RET 670’s unique and innovative sensitive differential protection feature, based on well-known theory of symmetrical components provide best possible coverage for

winding internal turn-to-turn faults.

A low impedance restricted earth-fault protection function is available as complimentary sensitive and fast main protection against winding earth

faults. This function includes a directional zero-sequence current criterion for additional security.

Alternatively a high impedance differential function is available.

It can be used as restricted earth

fault or, as three functions are included, also as differential protection on autotransformers,

as differential protection for a tertiary connected reactor, as T-differential protection for the transformer feeder in a mesh-corner or ring arrangement,

as tertiary bus protection etc.

Tripping from Buchholz and temperature devices can be done through the IED where pulsing, lock-out etc. is performed.

The binary inputs are heavily stabilized against disturbance to prevent incorrect operations at e.g. dc system capacitive discharges.

Distance protection functionality for phase to phase and/or phase to earth faults is available as back-up protection

for faults within the transformer and in the connected power system.

Versatile phase, earth, positive, negative and zero sequence overcurrent functions,

which can optionally be made directional and/or voltage controlled,

provide further alternative backup protection.

Thermal overload, volts per hertz, over/under voltage and over/under frequency protection functions are also available.

Built-in disturbance and event recorder provides valuable data to the user about status and operation for post-fault disturbance analysis.

Breaker failure protection for each transformer breaker allow high speed back-up tripping of surrounding breakers.

The IED can also be provided with a full control and interlocking functionality including Synchrocheck function to allow integration of the main or

a local back-up control.

The advanced logic capability, where user logic is prepared with a graphical tool, allows special applications such as

automatic opening of disconnectors in multi-breaker arrangements, closing of breaker rings, load transfer logic etc.

The graphical configuration tool ensures simple and fast testing and commissioning.

Serial data communication is via optical connections to ensure immunity against disturbances.

The wide application flexibility makes this product an excellent choice for both new installations and the refurbishment of existing installations.

Application

RET 670 provides fast and selective protection, monitoring and control for two- and three-winding

transformers, autotransformers, generator-transformer units, phase shifting transformers,

special railway transformers and shunt reactors.

The transformer IED is designed to operate correctly over a wide frequency range in order to accommodate power

system frequency variations during disturbances and generator start-up and shut-down.

A very fast differential protection function, with automatic CT ratio matching and vector group compensation,

makes this IED the ideal solution even for the most demanding applications.

RET 670 has very low requirements on the main CTs, no interposing CTs are required.

It is suitable for differential applications with multi-breaker arrangements with up to six restraint CT inputs.

The differential protection function is provided with 2nd harmonic and wave-block restraint features to avoid tripping for magnetizing inrush,

and 5th harmonic restraint to avoid tripping for overexcitation.

• Basic IED functions

– Self supervision with internal event list

– Time synchronization (TIME)

– Parameter setting groups

– Test mode functionality (TEST)

– Change lock function

– IED identifiers

– Rated system frequency

• Hardware

– Power supply module (PSM)

– Binary input module (BIM)

– Binary output module (BOM)

– Binary in/out module (IOM)

– mA input module (MIM)

– Transformer input module, standard compression connection terminals (TRM)

– Optical ethernet module (OEM)

– SPA/LON/IEC module (SLM)

– Line data communication module (LDCM)

– GPS time synchronization module (GSM)

• Accessories

– GPS antenna, including mounting kit

– External interface converter from C37.94 to G703

– High impedance resistor unit

– Test switch module RTXP24

– On/off switch

• Logic

– Tripping logic (PTRC, 94)

– Trip matrix logic

– Configurable logic blocks

– Fixed signal function block

• Monitoring

– Measurements (MMXU)

– Supervision of mA input signals (MVGGIO)

– Event counter (GGIO)

– Event function

– Disturbance report (RBDR)

• Metering

– Pulse counter logic (GGIO)

• Station communication

– IEC61850-8-1 communication

– LON communication protocol

– SPA communication protocol

– IEC 60870-5-103 communication protocol

– Horizontal communication via GOOSE for interlocking

– Single command, 16 signals

– Multiple Command, 80 blocks with 16 signals each

– Ethernet configuration of links

• Remote communication

– Binary signal transfer

• Voltage protection

– Two step undervoltage protection (PUVM, 27)

– Two step overvoltage protection (POVM, 59)

– Two step residual overvoltage protection(POVM , 59N)

– Overexcitation protection (PVPH, 24)

• Frequency protection

– Underfrequency protection (PTUF, 81)

– Overfrequency protection (PTOF, 81)

– Rate-of-change frequency protection (PFRC, 81)

• Multipurpose protection

– General current and voltage protection (GAPC)

• Secondary system supervision

– Current circuit supervision (RDIF)

– Fuse failure supervision (RFUF)

• Control

– Synchrocheck and energizing check (RSYN, 25)

– Apparatus control for single bay, max 8 app.(1CB) incl. Interlocking (APC8)

– Apparatus control for single bay, max 15 app.(2CBs) incl. Interlocking (APC15)

– Apparatus control for up to 6 bays, max 30 app. (6CBs) incl. Interlocking (APC30)

Functions

• Differential protection

– Transformer differential protection, two winding (PDIF, 87T)

– Transformer differential protection, three winding (PDIF, 87T)

– Restricted earth fault protection (PDIF, 87N)

– High impedance differential protection (PDIF, 87X)

• Distance protection

– Distance protection zones (PDIS, 21)

– Phase selection with load encroachment (PDIS, 21)

– Power swing detection (RPSB, 78)

– Automatic switch onto fault logic (PSOF)

• Current protection

– Instantaneous phase overcurrent protection (PIOC, 50)

– Four step phase overcurrent protection (POCM, 51/67)

– Instantaneous residual overcurrent protection (PIOC, 50N)

– Four step residual overcurrent protection (PEFM, 51N/67N)

– Thermal overload protection, two time constants (PTTR, 49)

– Breaker failure protection (RBRF, 50BF)

– Pole discordance protection (RPLD, 52PD)

• Directional overcurrent protection with four steps for each winding

– Each step can be inverse or definite time delayed

– Each step can be directional or non-directional

• Instantaneous high speed earth fault function with low transient overreach

• Directional earth fault protection with four stages for each winding

– Each step can be inverse or definite time delayed

– Each step can be directional or non-directional

– Each step can be blocked on second harmonic component

• Synchrocheck function for single- or multi-breaker arrangements:

– Selectable energizing direction

– Two functions with built-in voltage selection

• Selectable additional software functions such as

breaker failure protection for each breaker, voltage protection, overexcitation protection, control and monitoring

• Tripping from Buchholtz, temperature devices etc. through binary inputs stabilized against capacitive discharges

• Built-in data communication modules for station bus IEC 61850-8-1

• Data communication modules for station bus IEC 60870-5-103. LON and SPA

• Integrated disturbance and event recorder for up to 40 analog and 96 binary signals

• Time synchronization over IEC 61850-8-1. LON, SPA, binary input or with optional GPS module

• Analog measurements accuracy up to below 0.5% for power and 0.25% for current and voltage and with site calibration to optimize total accuracy

• Versatile local human-machine interface

• Extensive self-supervision with internal event recorder

• Six independent groups of complete setting parameters with password protection

• Powerful software PC tool for setting, disturbance evaluation and configuration

• Remote end data communication modules for C37.94 and G.703

Features

• A protection, control, and monitoring IED with extensive functional library and configuration

possibilities and expandable hardware design to meet specific user requirements

• For power transformers, autotransformers, shunt reactors, T-protection, generator transformer

blocks, phase shifting transformers and small busbar systems

• For two- and three-winding transformers with up to six stabilized inputs

• For multi- or single-breaker arrangements

• Transformer differential protection with:

– Percentage bias restraint for through faults

– Waveform and Second harmonic restraint for transformer inrush

– Fifth harmonic restraint for overexcitation

– High sensitivity for interturn faults

• Restricted earth fault protection for all direct or low impedance earthed windings

– Extremely fast operation

– High sensitivity

– High and low impedance based

• Full scheme phase-to-phase and phase-to-earth distance protection with up to five zones:

– Load encroachment feature

• Instantaneous high speed short circuit function with low transient overreach