Functional block diagram of the DGYD protection
General presentation
Two different types of busbar differential protection are available: the OGYD protection and the DGYD protection. Essentially, both work on the well-known principle that the sum of the currents entering and leaving a busbar is equal to zero when there is no internal fault. If this sum is not equal to zero, it means that there is a fault on the busbar and a fast tripping command is generated. The scheme used in both versions is that of a low impedance biased differential circuit, based on the application of Kirchhoff’s current law.
If the number of bays connected to the busbar is limited (6 bays maximum), the tasks of the three-phase busbar differential protection function are performed by a single device. If there are more bays, the tasks are shared between three independent devices. Each of them is responsible for the differential protection of one phase (L1, L2 or L3) of the busbar. This version can be considered as a centralised DGYD version.
The EuroCAP configuration tool, available free of charge, provides a user-friendly and flexible application for protection, control and measurement functions, ensuring that the protection devices are fully customisable.
General features
- Native intelligent electronic device (IED) compliant with the IEC 61850 standard, Edition 2 compatible
- Scalable hardware adapting to different applications
- Rack width of 84TE or 42TE (height: 3U)
- The predefined factory configuration can be customised to the user’s specifications with the powerful EuroCAP tool
- Flexible protection and control functionalities to meet specific user requirements
- Advanced HMI functionalities via a colour touch screen and a built-in web server, extended measurement, control and monitoring functions
- User-configurable LCD displays, able to show single line diagrams (SLD) with switchgear position indication and control, as well as measurement values and several types of controllable objects.
- Various protection setting groups available
- Enhanced circuit breaker monitoring and control
- High-capacity disturbance recorder (DRE) and event logging (data stored in non-volatile memory):
- DRE supporting up to 32 analogue signal channels and 64 digital signal channels.
- The event recorder can store more than 10,000 events.
- Several mounting methods: rack-mounted; flush-mounted; semi-flush-mounted; wall-mounted; wall-mounted with terminals; flush-mounted with IP54-rated cover.
- Wide range of communication protocols
- Ethernet communication: IEC 61850; IEC 60870-5-104; DNP3.0 TCP; Modbus TCP
- Serial communication: DNP3.0; IEC 60870-5-101/103; MODBUS, SPA
- The PROTECTA range can handle several communication protocols simultaneously.
- Built-in self-monitoring function to detect internal hardware or software errors.
- Various time sources available: NTP server; minute pulse; legacy protocol master; IRIG-B000 or IRIG-B12X
Applications
The DGYD model provides centralised, low impedance, fast and stable protection of busbars in electricity transmission and distribution networks.
Field of application
- The relay records the currents and status signals coming from all the protected bays of the busbar;
- Dynamic busbar replica, based on the status signals of the disconnectors;
- High stability in the event of external faults despite current transformer saturation;
- Short tripping time;
- Selectivity in the event of an internal fault: only the bays connected to the faulty busbar section are disconnected, all the other bays remain in service;
- Easy extension according to the busbar configuration;
- Easy adaptation of the function to different busbar configurations:
- Single busbar,
- Up to four busbars,
- Ring busbar,
- Breaker-and-a-half arrangement,
- Bus couplers,
- Busbar disconnectors with one or two current transformers,
- Transfer busbar;
- Individual digital calculation and decision-making for the three phases;
- Biased differential current characteristics;
- Increased security and stability thanks to specific software features;
- Voltage failure condition,
- Check zone criteria implemented to increase stability,
- Compensation of saturated waveforms.
- Digital differential protection
- Circuit breaker failure protection
Protection and control functions
The differential and circuit breaker failure functions are dealt with together because the circuit breaker failure protection uses the status information processed by the busbar protection in order to disconnect only the busbar section to which the faulty circuit breaker is connected. The other zones therefore remain in service.
Click on the link to download the general documentation : Please contact our Sales Department
Technical sheet : NC_DGYD
Click on the link to download the operation manual : Please contact our Sales Department
Click on the link to access the technical documentation to attach to your order : DOCACOM_PROTECTA
