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ABB Feeder Protection REF615 ANSI
The REF615 is powerful, most advanced and simplest feeder protection relay in its class, perfectly offering time and instantaneous overcurrent, negative sequence overcurrent, phase discontinuity, breaker failure and thermal overload protection. The relay also features optional high impedance fault (HIZ) and sensitive earth fault (SEF) protection for grounded and ungrounded distribution systems. Also, the relay incorporates a flexible three-phase multi-shot auto-reclose function for automatic feeder restoration in temporary faults on overhead lines. Enhanced with safety options, the relay offers a three-channel arc-fault detection system for supervision of the switchgear circuit breaker, cable and busbar compartments.
The REF615 also integrates basic control functionality, which facilitates the control of one circuit breaker via the relay’s front panel human machine interface (HMI) or remote control system. To protect the relay from unauthorized access and to maintain the integrity of information, the relay has been provided with a four-level, role-based user authentication system, with individual passwords for the viewer, operator, engineer and administrator level. The access control system applies to the front panel HMI, embedded web browser based HMI and the PCM600 relay setting and configuration tool.
Standardized communication
REF615 supports the new IEC 61850 standard for inter-device communication in substations. The relay also supports the industry standard DNP3.0 and Modbus® protocols.
The implementation of the IEC 61850 substation communication standard in REF615 encompasses both vertical and horizontal communication, including GOOSE messaging and parameter setting according to IEC 61850-8-1. The substation configuration language enables the use of engineering tools for automated configuration, commissioning and maintenance of substation devices.
Bus protection via GOOSE
The REF615 IEC 61850 implementation includes GOOSE messaging for fast horizontal relay-to-relay communication. Applying GOOSE communication to the REF615 relays of the incoming and outgoing feeders of a substation, a stable, reliable and high-speed bus protection system can be realized. The cost-effective GOOSE-based bus protection is obtained just by configuring the relays and the operational availability of the protection is assured by continuous supervision of the protection relays and their GOOSE messaging over the station communication network.
Costs are reduced since no separate physical input and output hard-wiring is needed for horizontal communication between the relays.
Bus protection via GOOSE
Pre-emptive condition monitoring
For continuous knowledge of the operational availability of the REF615 features, a comprehensive set of monitoring functions to supervise the relay health, the trip circuit and the circuit breaker health is included. The breaker monitoring can include checking the wear and tear of the circuit breaker, the spring charging time of the breaker operating mechanism and the gas pressure of the breaker chambers. The relay also monitors the breaker travel time and the number of circuit breaker (CB) operations to provide basic information for scheduling CB maintenance.
Rapid set-up and commissioning
Due to the ready-made adaptation of REF615 for the protection of feeders, the relay can be rapidly set up and commissioned, once it has been given the application- specific relay settings. If the relay needs to be adapted to the special requirements of the intended application, the flexibility of the relay allows the relay’s standard signal configuration to be adjusted by means of the signal matrix tool (SMT) included in its PCM600 relay setting and configuration user tool.
By means of Connectivity Packages containing complete descriptions of ABB’s protection relays, with data signals, parameters and addresses, the relays can be automatically configured via PCM600 relay setting and configuration user tool, COM600 Station Automation series devices, or MicroSCADA Pro substation automation system.
Unique draw-out design relay
The draw-out type relay design speeds up installation and testing of the protection. The factory-tested relay units can be withdrawn from the relay cases during factory and commissioning tests. The relay case provides automatic short-circuiting of the CT secondary circuits to prevent hazardous voltages from arising in the CT circuits when a relay plug-in unit is withdrawn from its case.
The pull-out handle locking the relay unit into its case can be sealed to prevent the unit from being unintentionally withdrawn from the relay case.
REF615 highlights
- Comprehensive overcurrent protection with high impedance fault, sensitive earth fault and thermal overload protection for feeder and dedicated protection schemes
- Simultaneous DN3.0 Level 2+ and Modbus Ethernet communications plus device connectivity and system interoperability according to the IEC 61850 standard for next generation substation communication
- Enhanced digital fault recorder functionality including high sampling frequency, extended length of records, 4 analog and 64 binary channels and flexible triggering possibilities
- High-speed, three-channel arc flash detection (AFD) for increased personal safety, reduced material damage and minimized system down-time
- Total control of the operational capability of the protection system through extensive condition monitoring of the relay and the associated primary equipment
- Draw-out type relay unit and a unique relay case design for a variety of mounting methods and fast installation, routine testing and maintenance
- One single tool for managing relay settings, signal configuration and disturbance handling
Analog inputs
- Three phase currents: 5/1 A
- Ground current: 5/1 A or 0.2 A
- Rated frequency: 60/50 Hz programmable
Binary inputs and outputs
- Four binary inputs with common ground
- Two NO double-pole outputs with TCM
- Two NO single-pole outputs
- One Form C signal output
- One Form C self-check alarm output
- Additional seven binary inputs plus three binary outputs (available as an option)
Communication
- IEC 61850-8-1 with GOOSE messaging
- DNP3.0 Level 2+ over TCP/IP
- Modbus over TCP/IP
- Time synchronization via SNTP (primary and backup servers)
- Optional serial RS-485 port programmable for DNP3.0 Level 2+ or Modbus RTU
Control voltage
- Option 1: 48 … 250 V dc, 100 … 240 V ac
- Option 2: 24 … 60 V dc
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SOURCE: ABB
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Related articles
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ANSI Functions For Protection Devices
In the design of electrical power systems, the ANSI Standard Device Numbers denote what features a protective device supports (such as a relay or circuit breaker). These types of devices protect electrical systems and components from damage when an unwanted event occurs, such as an electrical fault.
ANSI numbers are used to identify the functions of meduim voltage microprocessor devices.
ANSI facilitates the development of American National Standards (ANS) by accrediting the procedures of standards developing organizations (SDOs). These groups work cooperatively to develop voluntary national consensus standards. Accreditation by ANSI signifies that the procedures used by the standards body in connection with the development of American National Standards meet the Institute’s essential requirements for openness, balance, consensus and due process.
Current protection functions
ANSI 50/51 – Phase overcurrent
Three-phase protection against overloads and phase-to-phase short-circuits.
ANSI index ↑
ANSI 50N/51N or 50G/51G – Earth fault
Earth fault protection based on measured or calculated residual current values:
- ANSI 50N/51N: residual current calculated or measured by 3 phase current sensors
- ANSI 50G/51G: residual current measured directly by a specific sensor
ANSI 50BF – Breaker failure
If a breaker fails to be triggered by a tripping order, as detected by the non-extinction of the fault current, this backup protection sends a tripping order to the upstream or adjacent breakers.
ANSI index ↑
ANSI 46 – Negative sequence / unbalance
Protection against phase unbalance, detected by the measurement of negative sequence current:
- sensitive protection to detect 2-phase faults at the ends of long lines
- protection of equipment against temperature build-up, caused by an unbalanced power supply, phase inversion or loss of phase, and against phase current unbalance
ANSI 49RMS – Thermal overload
Protection against thermal damage caused by overloads on machines (transformers, motors or generators).
The thermal capacity used is calculated according to a mathematical model which takes into account:
- current RMS values
- ambient temperature
- negative sequence current, a cause of motor rotor temperature rise
Recloser
ANSI 79
Automation device used to limit down time after tripping due to transient or semipermanent faults on overhead lines. The recloser orders automatic reclosing of the breaking device after the time delay required to restore the insulation has elapsed. Recloser operation is easy to adapt for different operating modes by parameter setting.
ANSI index ↑
Directional current protection
ANSI 67N/67NC type 1
ANSI 67 – Directional phase overcurrent
Phase-to-phase short-circuit protection, with selective tripping according to fault current direction. It comprises a phase overcurrent function associated with direction detection, and picks up if the phase overcurrent function in the chosen direction (line or busbar) is activated for at least one of the 3 phases.
ANSI index ↑
ANSI 67N/67NC – Directional earth fault
Earth fault protection, with selective tripping according to fault current direction.
3 types of operation:
- type 1: the protection function uses the projection of the I0 vector
- type 2: the protection function uses the I0 vector magnitude with half-plane tripping zone
- type 3: the protection function uses the I0 vector magnitude with angular sector tripping zone
ANSI 67N/67NC type 1
Directional earth fault protection for impedant, isolated or compensated neutralsystems, based on the projection of measured residual current.
ANSI index ↑
ANSI 67N/67NC type 2
Directional overcurrent protection for impedance and solidly earthed systems, based on measured or calculated residual current. It comprises an earth fault function associated with direction detection, and picks up if the earth fault function in the chosen direction (line or busbar) is activated.
ANSI index ↑
ANSI 67N/67NC type 3
Directional overcurrent protection for distribution networks in which the neutral earthing system varies according to the operating mode, based on measured residual current. It comprises an earth fault function associated with direction detection (angular sector tripping zone defined by 2 adjustable angles), and picks up if the earth fault function in the chosen direction (line or busbar) is activated.
ANSI index ↑
Directional power protection functions
ANSI 32P – Directional active overpower
Two-way protection based on calculated active power, for the following applications:
- active overpower protection to detect overloads and allow load shedding
- reverse active power protection:
- against generators running like motors when the generators consume active power
- against motors running like generators when the motors supply active power
ANSI 32Q/40 – Directional reactive overpower
Two-way protection based on calculated reactive power to detect field loss on synchronous machines:
- reactive overpower protection for motors which consume more reactive power with field loss
- reverse reactive overpower protection for generators which consume reactive power with field loss.
Machine protection functions
ANSI 37 – Phase undercurrent
Protection of pumps against the consequences of a loss of priming by the detection of motor no-load operation.
It is sensitive to a minimum of current in phase 1, remains stable during breaker tripping and may be inhibited by a logic input.
ANSI index ↑
ANSI 48/51LR/14 – Locked rotor / excessive starting time
Protection of motors against overheating caused by:
- excessive motor starting time due to overloads (e.g. conveyor) or insufficient supply voltage.
The reacceleration of a motor that is not shut down, indicated by a logic input, may be considered as starting. - locked rotor due to motor load (e.g. crusher):
- in normal operation, after a normal start
- directly upon starting, before the detection of excessive starting time, with detection of locked rotor by a zero speed detector connected to a logic input, or by the underspeed function.
ANSI 66 – Starts per hour
Protection against motor overheating caused by:
- too frequent starts: motor energizing is inhibited when the maximum allowable number of starts is reached, after counting of:
- starts per hour (or adjustable period)
- consecutive motor hot or cold starts (reacceleration of a motor that is not shut down, indicated by a logic input, may be counted as a start)
- starts too close together in time: motor re-energizing after a shutdown is only allowed after an adjustable waiting time.
ANSI 50V/51V – Voltage-restrained overcurrent
Phase-to-phase short-circuit protection, for generators. The current tripping set point is voltage-adjusted in order to be sensitive to faults close to the generator which cause voltage drops and lowers the short-circuit current.
ANSI index ↑
ANSI 26/63 – Thermostat/Buchholz
Protection of transformers against temperature rise and internal faults via logic inputs linked to devices integrated in the transformer.
ANSI index ↑
ANSI 38/49T – Temperature monitoring
Protection that detects abnormal temperature build-up by measuring the temperature inside equipment fitted with sensors:
- transformer: protection of primary and secondary windings
- motor and generator: protection of stator windings and bearings.
Voltage protection functions
ANSI 27D – Positive sequence undervoltage
Protection of motors against faulty operation due to insufficient or unbalanced network voltage, and detection of reverse rotation direction.
ANSI index ↑
ANSI 27R – Remanent undervoltage
Protection used to check that remanent voltage sustained by rotating machines has been cleared before allowing the busbar supplying the machines to be re-energized, to avoid electrical and mechanical transients.
ANSI index ↑
ANSI 27 – Undervoltage
Protection of motors against voltage sags or detection of abnormally low network voltage to trigger automatic load shedding or source transfer.
Works with phase-to-phase voltage.
ANSI index ↑
ANSI 59 – Overvoltage
Detection of abnormally high network voltage or checking for sufficient voltage to enable source transfer. Works with phase-to-phase or phase-to-neutral voltage, each voltage being monitored separately.
ANSI index ↑
ANSI 59N – Neutral voltage displacement
Detection of insulation faults by measuring residual voltage in isolated neutral systems.
ANSI index ↑
ANSI 47 – Negative sequence overvoltage
Protection against phase unbalance resulting from phase inversion, unbalanced supply or distant fault, detected by the measurement of negative sequence voltage.
ANSI index ↑
Frequency protection functions
ANSI 81H – Overfrequency
Detection of abnormally high frequency compared to the rated frequency, to monitor power supply quality.
ANSI index ↑
ANSI 81L – Underfrequency
Detection of abnormally low frequency compared to the rated frequency, to monitor power supply quality. The protection may be used for overall tripping or load shedding. Protection stability is ensured in the event of the loss of the main source and presence of remanent voltage by a restraint in the event of a continuous decrease of the frequency, which is activated by parameter setting.
ANSI index ↑
ANSI 81R – Rate of change of frequency
Protection function used for fast disconnection of a generator or load shedding control. Based on the calculation of the frequency variation, it is insensitive to transient voltage disturbances and therefore more stable than a phase-shift protection function.
Disconnection
In installations with autonomous production means connected to a utility, the “rate of change of frequency” protection function is used to detect loss of the main system in view of opening the incoming circuit breaker to:
- protect the generators from a reconnection without checking synchronization
- avoid supplying loads outside the installation.
Load shedding
The “rate of change of frequency” protection function is used for load shedding in combination with the underfrequency protection to:
- either accelerate shedding in the event of a large overload
- or inhibit shedding following a sudden drop in frequency due to a problem that should not be solved by shedding.
Related book: Relay selection guide
Link: Register
Autor: Edvard Csanyi, CsanyiGroup
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Related articles
Short Circuit Parameters in Low Voltage AC Circuits
Low-voltage equipment standards IEC60947 and IEC60439 currently include short-circuit ratings for products and assemblies respectively, defined in terms of the ability of the equipment to operate at a level of peak current, an RMS current for a specified time and/or a level of current conditional upon a short-circuit protective device in series. In practice the correct application of the various short-circuit ratings needs to be fully understood by the circuit designer to avoid leaving a circuit or equipment with inadequate short-circuit protection. It is also useful to take full advantage of the capability of devices and systems to avoid over-engineering, with the consequent unnecessary additional cost. This guide does not concern itself with the issue of selectivity between devices in series, which must be considered separately.
Principles of Application
The Installation
In order to ensure the capability of equipment under short-circuits conditions the circuit designer must firstly have available the prospective fault level at the point of installation of each item of equipment. This is produced by a system protection study. IEC60781 provides an application guide for calculation of short-circuit currents in lowvoltage radial systems. Short-circuit parameters are defined by this guide in terms, which include the following:
- Prospective (available) short-circuit current:
The current that would flow if the short-circuit were replaced by an ideal connection of negligible impedance without any change of the supply. - Peak short-circuit current Ip
The maximum possible instantaneous value of the prospective (available) short-circuit current. - Symmetrical short-circuit breaking current Ib
The r.m.s. value of an integral cycle of the symmetrical a.c. component of the prospective (available) shortcircuit current at the instant of contact separation of the first pole of a switching device. - Steady-state short-circuit current Ik
The r.m.s. value of the short-circuit current which remains after the decay of the transient phenomena.
- unlimited
- limited by an SCPD (short-circuit protective device)
LV Assemblies (switchboard, distribution board etc.)
An assembly will have a short-circuit rating, assigned by the manufacturer, defined in terms of the maximum prospective fault level applicable at the point it is connected into the system.
This will have been determined by test and/or design calculations as specified in the assembly standard, IEC60439-1, or applicable part thereof.
The terminology to define the short-circuit rating of an assembly is given in the standard as follows:
- Rated short-time current (Icw) (of a circuit of an assembly)
Summarised as: The r.m.s value of short-time current that a circuit of an assembly can carry without damage under specified test conditions, defined in terms of a current and time e.g. 20kA, 0,2s. - Rated peak withstand current (Ipk) (of a circuit of an assembly)
Summarised as: The value of peak current that a circuit can withstand satisfactorily under specified test conditions. - Rated conditional short-circuit current (Icc) (of a circuit of an assembly)
Summarised as: The value of prospective short-circuit current that a circuit, protected by a specified shortcircuit protective device (SCPD), can withstand satisfactorily for the operating time of that device, under specified test conditions. Note: the short-circuit protective device may form an integral part of the assembly or may be a separate unit.An assembly may be assigned a value of Icc alone.
- An assembly may be assigned values of Icw and Ipk (but cannot be assigned a value of Icw or Ipk alone).
- An assembly may be assigned values of Icw, Ipk and Icc.
- An assembly may be assigned different values of Icc for different circuit protective devices and/or system voltages.
- An assembly may be assigned different values of Icw for different short-time periods e.g. 0.2s, 1s, 3 s.
Switchgear
In terms of short-circuit capability switchgear must be considered in respect of it’s function in the particular application. A switching device is considered in two respects, self-protection and use as a short-circuit protective device (SCPD) where applicable.
Switchgear – Self Protection Against Short Circuit
Two cases are considered:
- Load and overload switching alone, without any short-circuit switching capability:
In this case the switching device will be short-circuit rated on a similar basis to a circuit of an assembly (see above), with a rating of Icw and/or a conditional short-circuit rating, but will in addition have a rated short-circuit making capacity Icm. - Load, overload and short-circuit switching capability:
- Fused switchgear – in this case the short-circuit breaking function is provided by the integral fuses and the device will have a conditional short-circuit rating
- Circuit breakers – the circuit-breaker will be self-protecting up to its breaking capacity rating (see later). At fault levels above the breaking capacity rating a circuit-breaker may be capable of operating with ‘back-up’ protection by an SCPD (this is in effect a conditional rating, but the term is not generally used in this context).
Switchgear – Application as SCPD
- Fused Switchgear and Fuses as SCPD
Since the short-circuit breaking function in fused switchgear is provided by the fuses it is the fuse characteristics that are considered. These are given in IEC60269-1 as follows:- Breaking capacity of a fuselink
- value (for a.c. the r.m.s. value of the a.c. component) of prospective current that a fuselink is capable of breaking at a stated voltage under prescribed conditions. - Cut-off current
Summarised as: maximum instantaneous value reached by the current during the breaking operation of a fuselink when it operates to prevent the current reaching the prospective peak. - Operating I²t (Joule integral)
Summarised as: Integral of the square of the current over the operating time of the fuse.
Sometimes referred to as ‘energy let-through’. When expressed in A²t gives the energy dissipated per ohm and thus represents the thermal effect on the circuit.
- Breaking capacity of a fuselink
- Circuit-breakers as SCPD
- Moulded-case circuit-breakers (MCCBs) and air circuit-breakers (ACBs) are rated according to IEC60947-2 as follows
- Rated short-circuit making capacity (Icm)
Summarised as: The maximum peak prospective current that the circuit-breaker can make on to satisfactorily.
- Rated short-circuit making capacity (Icm)
- Rated short-circuit breaking capacities:
- Rated ultimate short-circuit breaking capacity (Icu)
Summarised as: The r.m.s prospective current that the circuit breaker is capable of breaking at a specified voltage under defined test conditions, which include one break and one make/break operations. - Rated service short-circuit breaking capacity (Ics)
Summarised as: The r.m.s prospective current that the circuit breaker is capable of breaking at a specified voltage under defined test conditions, which include one break and two make/break operations. The standard specifies fixed relationships to Icu of 25, 50, 75 or 100%. - Rated short-time withstand current (Icw)
Summarised as: The r.m.s value of short-time current assigned by the manufacturer based on specified test conditions. Minimum values are given in the standard.
- Rated ultimate short-circuit breaking capacity (Icu)
- Moulded-case circuit-breakers (MCCBs) and air circuit-breakers (ACBs) are rated according to IEC60947-2 as follows
A circuit-breaker can only be assigned a rated short-time withstand current Icw if it is equipped with a time-delay overcurrent release.
All circuit-breakers to IEC60947-2 will have values of Icu and Ics.
Characteristics of circuit-breakers not mandated in IEC60947-2 but having application to short-circuit protection:
- Cut-off current
The maximum instantaneous value reached by the current during the breaking operation of a circuit-breaker when it operates to prevent the current reaching the prospective peak. - Operating I²t (Joule integral)
Integral of the square of the current over the operating time of the circuit-breaker on a short-circuit. Sometimes referred to as ‘energy let-through’. When expressed in A²t gives the energy dissipated per ohm and thus represents the thermal effect on the circuit.
Examples of the Practical Application of the Product Characteristics
In simple studies only the r.m.s value of steady-state short-circuit current (Ik) is quoted. The peak current is assumed to be in a standard relationship to the r.m.s current, determined by the overall power factor, and taken into account in the rating of SCPDs to the respective IEC standards.
Circuit Protection
The application of short-circuit protective devices (SCPD) to circuit protection i.e. the protection of cables, is detailed in the installation rules, IEC364. In general it is accepted that selection of the protective device on the basis of thermal protection of a cable automatically provides short-circuit protection up to the breaking capacity of the SCPD, in the case of non-time-delayed devices.
Short-Circuit Protection for LV assemblies
Switchboard/Motor-Control Centre
The prospective short-circuit current at the input to the switchboard is obtained from a system protection study.
This will be given as an r.m.s value.
- If the switchboard has an Icw current value higher than the prospective current level then the only requirement is to limit the time for which a short-circuit could persist to within the short-time value. This is achieved by the setting of releases upstream or at the incomer to the switchboard.
- If the switchboard has an Icc rating higher than the prospective current level then the only requirement is to include the specified SCPD in the circuit. This may be added in the circuit upstream or may already be included as an incomer to the switchboard.
Busbar Trunking (BBT)
The prospective short-circuit current at the input to the switchboard is obtained from a system protection study.
This will be given as an r.m.s value.
- If the BBT has an Icw current value higher than the prospective short circuit current level then the only requirement is to limit the time for which a short-circuit could persist to within the short-time value. This is achieved by the time-delay setting of overcurrent releases upstream.
- If the BBT has an Icw lower than the prospective short circuit current level Ik but has an Icc rating higher than Ik then the only requirement is to include the specified SCPD in the circuit upstream or in the end-feed unit. The suitability of any given SCPD may be derived from the cut-off current and Joule-integral characteristics by comparison with proof-test parameters.
Motor Control Gear (MCG)
Motor starters and contactors are not generally self-protecting against the effects of short-circuit and therefore need to be associated with an SCPD. In this particular case test procedures to IEC60947-4-1 recognise the difficulty of protecting sensitive devices from damage under heavy short-circuit conditions. Thus a special case of conditional rating is obtained which allows two classes of co-ordination with an SCPD:
Type 1 – in which a certain amount of damage to the MCG is accepted.
Type 2 – in which the MCG is capable of further use.
These ratings can only be obtained by type-testing and thus the data must be obtained from the manufacturer of the SCPD or the MCG.
Miniature Circuit Breakers (MCBs)
When applied in other than domestic (household) situations the short-circuit capability of MCBs to IEC60898 is often inadequate and they need to be ‘backed-up’ by another SCPD. Details of how the appropriate SCPD is determined are given, for circuit-breakers, in Appendix A of IEC60947-2. Basically this shows that only testing of the required combination is satisfactory and thus the data must be obtained from the manufacturer of the SCPD or the MCB. The same applies to fuses used as SCPD.
Izvor: www.voltimum.co.uk
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