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The main features of the relay are

Self-powered three-phase non-directional overcurrent and earth fault protection with DMT and IDMT characteristics

Dual earth fault measurement modes – internal vector summing or external CBCT inputs

Integration of IDMT curves (IEC and special) in a single product to meet the time-coordinated requirements of secondary distribution protection

Protection blocking via second harmonic measurement to ensure stability during transformer magnetic surges

Capacitive discharge pulse output for low-energy trip coils

Built-in manual reset electromechanical sign for trip indication

Easy setup via DIP switches, protected by transparent cover

Compact design and mounting for ring main unit (RMU) applications

Test equipment for testing the entire program, including primary CTs, relays and trip coils

Operating instructions

The combined overcurrent and earth fault relay is a secondary relay that is connected to the current transformer of the protected object.

In addition to the measurements (inputs), the relay receives from the current transformer the energy required for its own operation and for tripping the circuit breakers.

There are two LEDs on the front panel. The green “Ready” indicator lights up when the minimum current required for operation is available, indicating that the relay is operating.

When a fault is detected, the relay will trip the circuit breaker according to the setting.

The relay will also perform periodic internal health checks and notify the user of any faults within the relay.

Internal relay faults are indicated by the red LED “IRF” indicator.

The overcurrent device will operate when the phase current exceeds the set run time for timed operation or the calculated run time for inverse time limit operation.

Operation. Similarly, the high level I>> of the overcurrent device will actuate when the set operation time has expired.

The ground fault unit operates when the ground fault current exceeds the set operation time for timed operation or the calculated operation time for inverse time limit operation.

Similarly, the high level I0>> of the ground-fault unit operates when the set operation time expires.

The low-level rectification stage of the overcurrent unit and the low-level rectification stage of the ground-fault unit can have a deterministic time or inverse deterministic minimum time (IDMT) characteristic.

When the IDMT characteristic is selected, four standard www.cniacs.com time/current curves and three special time/current curves are available.

The standard curves conform to BS142 and IEC 60255 and are referred to as normal inverse time, extreme inverse time, extreme inverse time and long time inverse time.

In addition, three special curves are available, namely the RI curve, the HR fuse curve and the FR fuse curve.

Product Features

Capacitor bank overload and unbalance protection, non-directional overcurrent and directional ground fault protection, voltage and frequency based protection and measurement functions

Current-based unbalance protection, compensation for natural unbalance, and current-based capacitor bank switching resonance protection

Optional arc protection and high-speed output

Supports IEC 61850 version 1 and 2. including HSR and PRP, GOOSE messaging, and IEC 61850-9-2 LE to minimize wiring and supervised communications

IEEE 1588 V2 for high-precision time synchronization and maximum benefits of Ethernet communications at the substation level

Supports Modbus, DNP3 and IEC 60870-5-103 communication protocols

Applications

The REV615 is designed for primary protection of H-bridge, double Y-type and single Y-type connected capacitor banks and feeder cables.

In addition, the REV615 can be used to protect harmonic filter circuits when the harmonic component is not higher than the 11th.

The REV615 is available in two standard configurations, both of which provide three-phase overload protection, current-based unbalance protection (natural unbalance compensation), and current-based capacitor bank switching resonance protection.

The overload protection includes an integrated undercurrent function that detects the disconnection of the capacitor bank and inhibits the closing of the circuit breaker when the capacitor bank is partially charged.

Three-phase thermal overload protection is available www.cniacs.com for reactors and resistors in harmonic filter circuits.

The REV615 also provides non-directional overcurrent and ground fault protection for capacitor banks and their feeder cables.

Standard configuration B also provides directional ground fault, residual voltage, voltage unbalance, and over- and under-voltage protection.

Standard configuration A is pre-configured for H-bridge connected capacitor banks with three-phase unbalance protection.

Standard configuration B is pre-configured for capacitor banks with double Y-bridge connection and has single current unbalance protection.

The standard configurations can be customized to meet the requirements of the application with the IEC 61850-compliant protection and control IED manager PCM600.

Range

Busbar and ideal multi-purpose back-up protection relays

Product Benefits

Pre-configured features for busbar protection applications

Relays are delivered pre-configured and factory tested to reduce engineering and commissioning time

Self-healing communication based on HSR/PRP using an optional second Ethernet bus

Compact design makes it suitable for both new and retrofit installations

Pull-out plug-in design for quick installation and testing

Product Features

Bus and ideal multi-purpose backup protection

Powerful and user-friendly web browser-based human machine interface (HMI), including input/output (I/O) matrix with visualization options

Application-specific standard configurations reduce relay setup and commissioning time

Supports IEC 61850 version 1 and 2. including www.cniacs.com binary GOOSE messages

Pre-configured solutions for utility distribution and industrial applications

Therefore, several of the rules for hardening automation systems apply to these systems as well. From an automation system perspective, protection and control relays are at the bottom of the hierarchy, closest to the actual main processes. It is important to apply the “defense-in-depth” information security concept, whereby each layer in the system is capable of protecting the automation system, and therefore the protection and control relays are part of this concept. The following points should be considered when planning system protection.

– Recognize and familiarize yourself with all parts of the system and the system’s communication links

– Remove all unnecessary communication links from the system

– Rate the safety level of the remaining connections and improve them using applicable methods

– Harden the system by removing or deactivating all unused processes, communication ports, and services

– Check that all applicable parts of the entire system are backed up

– Collect and store backups of system components and keep them up to date

– Remove all unnecessary user accounts

– Define password policies

– Change default passwords and use strong passwords

– Check that strong encryption and authentication is used for links from the substation to higher-level systems

– Separate public (untrusted) from automated (trusted) networks

– Isolate traffic and networks

– Use firewalls and demilitarized zones

– Evaluate systems regularly

– Use malware protection in workstations and keep it up www.cniacs.com to date It is important to utilize defense-in-depth concepts when designing automated system security. Connecting devices directly to the Internet is not recommended without adequate additional security components. Security controls should be used for the different layers and interfaces in the system. In addition to product features, strong security means enabling and using available features and enforcing their use according to company policy. Proper training of personnel accessing and using the system is also required.

The REX 521 is primarily used in single-bus solutions for various protections using a single circuit breaker.

With pre-fabricated standard configurations, the unit can be used in different types of networks. Typical applications include input and output feeders in radially isolated neutral, resonant grounded, solid grounded and resistance grounded systems.

Scope

Protection, control, measurement and monitoring in medium voltage networks and for the protection of medium and large three-phase AC motors

Product advantages

Multifunctional protection

Product features

energized inputs for conventional current and voltage transformers

Versions with current and voltage sensor inputs also available

Prefabricated, standard configuration

REX 521 Relay Protection Unit

The REX 521 relay protection unit is designed for protection, control, measurement and monitoring of medium voltage networks.

Typical applications include incoming and outgoing feeders and substation protection.

The relay protection unit is equipped with energized inputs for conventional current and voltage transformers.

Hardware versions with current and voltage sensor inputs are also available.

The relay protection unit is based on a multiprocessor environment.

The human-machine interface includes an LCD display with different views for local use and informs the user with prompt messages.

Both hardware and software solutions utilize modern technology.

REX 521 is part of the Distribution Automation substation automation concept and further extends the functionality and flexibility of the concept.