Overview

Protecta offers two different types of busbar protection. Essentially, both work on the well-known principle: the sum of the currents flowing into and out of the busbar results zero if there are no internal faults. If the sum is not zero, there is an internal fault and a fast trip command is generated. The scheme in both versions is the low-impedance, biased differential scheme, the application of Kirchhoff`s node law.

The difference between the two types is the structure of the differential protection system:

• Distributed (Decentralized) version:

In this version other individual protective devices of the bays (distance protection, overcurrent protection, etc., or potentially dedicated bay units) are involved in the busbar protection scheme as bay units. Their location in the substation depends on the bay structure of the primary system. These devices perform the sampling of the currents and they have access to all information needed for the busbar protection system.This information is sent by a fiber optic link to the central unit. The calculation and decision is performed by the central unit and the dedicated trip commands are sent back to the devices also via fiber optic links.

• Centralized version:

If the number of bays connected to the busbar is limited (there are a maximum of 6 bays), the tasks related to the three-phase busbar differential protection function are performed within one device. If there are more bays, the tasks are divided among 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 centralized version.

The EuroCAP configuration tool, which is available free of charge, offers a user-friendly and flexible application for protection, control and measurement functions to ensure that the IED-EP+ devices are fully customisable.

General features

• Native IEC 61850 IED with Edition 2 compatibility
• Scalable hardware to adapt to different applications
• 84 HP or 42HP wide rack size (height: 3U)
• The pre-defined factory configuration can be customized to the user’s specification with the powerful EuroCAP tool
• Flexible protection and control functionality to meet special customer requirements
• Advanced HMI functionality via color touchscreen and embedded WEB server, extended measuring, control and monitoring functions
• User configurable LCD user screens, which can display SLDs (Single Line Diagrams) with switchgear position indication and control as well as measuring values and several types of controllable objects.
• Various protection setting groups available
• Enhanced breaker monitoring and control
• High capacity disturbance recorder (DRE) and event logging (data is stored in non-volatile memory):
• DRE for up to 32 analogue and 64 digital signal channels.
• Event recorder can store more than 10,000 events.
• Several mounting methods: Rack; Flush mounting; Semi-flush mounting; Wall mounting; Wall-mounting with terminals; Flush mounting with IP54 rated cover.
• Wide range of communication protocols:
• Ethernet-based communication: IEC61850; IEC60870-5-104; DNP3.0 TCP; Modbus TCP
• Serial communication: DNP3.0; IEC60870-5-101/103; MODBUS, SPA
• The EuroProt+ family can handle several communication protocols simultaneously.
• Built-in self-monitoring to detect internal hardware or software errors
• Different time sources available: NTP server; Minute pulse; Legacy protocol master; IRIG-B000 or IRIG-B12X

Application

The DGYD type performs fast and stable centralized low-impedance busbar protection in transmission and utility systems. It is a member of the EuroProt+ product family.

Scope of application

• The relay collects currents and status signals from all protected bays of the busbar;
• Dynamic busbar replica, based on disconnector status signals;
• High stability in case of external faults in spite of current transformer saturation;
• Short tripping time;
• Selectivity for internal fault, only the bays connected to the faulty busbar section are disconnected, all other bays remain in continuous operation;
• Easy to extend according to the busbar configuration;

• Easy adaptation of the function for different primary bus systems:
• Single busbar,
• Up to quadruple busbar,
• Ring bus,
• 1 ½ circuit breaker arrangement,
• Bus couplers,
• Bus sectionalizers with one or two current transformers,
• Transfer bus;
• Individual numerical calculation and decision for all three phases;
• Stabilized differential current characteristics;
• Security and stability are increased through special software features;
• Voltage breakdown condition,
• Implemented Check zone criteria to increase stabilit,
• Saturated waveform compensation.

The DGYD type is a collection of the following configurations:

• E11-CBBP: Centralized single-phase busbar protection for 12 bays
• E14-CBBP: Centralized single-phase busbar protection for 16 bays
• E15-CBBP: Centralized single-phase busbar protection for 20 bays
• E16-CBBP: Centralized single-phase busbar protection for 24 bays
• E33-CBBP: Centralized three-phase busbar protection for 3 bays*
• E34-CBBP: Centralized three-phase busbar protection for 4 bays*
• E35-CBBP: Centralized three-phase busbar protection for 5 bays*
• E36-CBBP: Centralized three-phase busbar protection for 6 bays*

* The number of bus sections is user defined

Protection & control functions

The numerical protection integrates two independent protection functions:

• Numerical differential protection
• Breaker failure protection

These functions are discussed together because breaker failure protection utilizes the processed status information of the busbar protection to disconnect only the section of the busbar to which the faulty circuit breaker is connected. Consequently, other zones may remain in continuous service.

Documentation

Order

• E11-CBBP_F: Centralized single-phase busbar protection for 12 bays
• E14-CBBP_F: Centralized single-phase busbar protection for 16 bays
• E15-CBBP_F: Centralized single-phase busbar protection for 20 bays
• E16-CBBP_F: Centralized single-phase busbar protection for 24 bays

• E33-CBBP_F: Centralized three-phase busbar protection for 3 bays
• E34-CBBP_F: Centralized three-phase busbar protection for 4 bays
• E35-CBBP_F: Centralized three-phase busbar protection for 5 bays
• E36-CBBP_F: Centralized three-phase busbar protection for 6 bays