RELAY SYSTEM OVERVIEW

1.1 Hardware overview

The relay hardware is based on a modular design whereby the relay is made up of several modules which are drawn from a standard range. Some modules are essential while others are optional depending on the user’s requirements.

The different modules that can be present in the relay are as follows:

1.1.1 Power supply module

The power supply module provides a power supply to all of the other modules in the relay, at three different voltage levels. The power supply board also provides the RS485 electrical connection for the rear communication port. On a second board the power supply module contains relays which provide the output contacts.

1.1.2 Main processor board

The processor board performs most of the calculations for the relay (fixed and programmable scheme logic, protection functions other than distance protection) and controls the operation of all other modules within the relay. The processor board also contains and controls the user interfaces (LCD, LEDs, keypad and communication interfaces).

1.1.3 Co-processor board

The co-processor board manages the acquisition of analogue quantities, filters them and calculates the thresholds used by the protection functions. It also processes the distance algorithms.

1.1.4 Input module

The input module converts the information contained in the analogue and digital input signals into a format suitable for the co-processor board. The standard input module consists of two boards: a transformer board to provide electrical isolation and a main input board which provides analogue to digital conversion and the isolated digital inputs.

1.1.5 Input and output boards

(1) Universal voltage range opto inputs N/O – normally open C/O – change over Since version C2.X:

• P444 could manage in option : 46 outputs

• Fast outputs can be ordered following the cortec reference (available in the Technical Data Sheet document)

• See also the hysteresis values of the optos in the §6.2 from chapter AP 1.1.6 IRIG-B board (P442 and P444 only)

This board, which is optional, can be used where an IRIG-B signal is available to provide an accurate time reference for the relay. There is also an option on this board to specify a fibre optic rear communication port, for use with IEC60870 communication only.

All modules are connected by a parallel data and address bus which allows the processor board to send and receive information to and from the other modules as required. There is also a separate serial data bus for conveying sample data from the input module to the processor. figure 1 shows the modules of the relay and the flow of information between them.

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Main processor board

Relay board

Power supply board Transformer board

Input board Parallel data bus

E²PROM SRAM Flash

EPROM

CPU Front LCD panel RS232 Front comms port

Parallel test port LEDs

Current & voltage inputs (6 to 8)

Digital inputs (x8 or x16 or x24)

Power supply

Rear RS485 communication port

Output relay contacts (x14 or x21 or x32)

ADC

Output relays Opto-isolated inputs

Analogue input signals Power supply (3 voltages),

rear comms data

Digital input values Power supply, rear comms

data, output relay status

Serial data bus (sample data) Alarm, event, fault,

FIGURE 1 - RELAY MODULES AND INFORMATION FLOW

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1.1.7 Second rear comms and InterMiCOM board (optional since version C2.X)

The optional second rear port is designed typically for dial-up modem access by protection engineers/operators, when the main port is reserved for SCADA traffic. It is denoted “SK4”.

Communication is via one of three physical links: K-Bus, EIA(RS)485 or EIA(RS)232. The port supports full local or remote protection and control access by MiCOM S1 software. The second rear port is also available with an on board IRIG-B input.

The optional board also houses port “SK5”, the InterMiCOM teleprotection port. InterMiCOM permits end-to-end signalling with a remote P440 relay, for example in a distance protection channel aided scheme. Port SK5 has an EIA(RS)232 connection, allowing connection to a MODEM, or compatible multiplexers.

1.1.8 Ethernet board (from version C2.0 up to C2.7)

This is a mandatory board for UCA2.0 enabled relays. It provides network connectivity through either copper or fibre media at rates of 10Mb/s or 100Mb/s. This board, the IRIG-B board and second rear comms board are mutually exclusive as they both utilise slot A within the relay case.

1.2 Software overview

The software for the relay can be conceptually split into four elements: the real-time operating system, the system services software, the platform software and the protection and control software. These four elements are not distinguishable to the user, and are all processed by the same processor board. The distinction between the four parts of the software is made purely for the purpose of explanation here:

1.2.1 Real-time operating system

The real time operating system is used to provide a framework for the different parts of the relay’s software to operate within. To this end the software is split into tasks. The real-time operating system is responsible for scheduling the processing of these tasks such that they are carried out in the time available and in the desired order of priority.

The operating system is also responsible for the exchange of information between tasks, in the form of messages.

1.2.2 System services software

The system services software provides the low-level control of the relay hardware. For example, the system services software controls the boot of the relay’s software from the non-volatile flash EPROM memory at power-on, and provides driver software for the user interface via the LCD and keypad, and via the serial communication ports. The system services software provides an interface layer between the control of the relay’s hardware and the rest of the relay software.

1.2.3 Platform software

The platform software deals with the management of the relay settings, the user interfaces and logging of event, alarm, fault and maintenance records. All of the relay settings are stored in a database within the relay which provides direct compatibility with Courier communications. For all other interfaces (i.e. the front panel keypad and LCD interface, Modbus and IEC60870-5-103) the platform software converts the information from the database into the format required. The platform software notifies the protection & control software of all setting changes and logs data as specified by the protection & control software.

1.2.4 Protection & control software

The protection and control software performs the calculations for all of the protection algorithms of the relay. This includes digital signal processing such as Fourier filtering and ancillary tasks such as the measurements. The protection & control software interfaces with the platform software for settings changes and logging of records, and with the system services software for acquisition of sample data and access to output relays and digital opto-isolated inputs.

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1.2.5 Disturbance Recorder

The disturbance recorder software is passed the sampled analogue values and logic signals from the protection and control software. This software compresses the data to allow a greater number of records to be stored. The platform software interfaces to the disturbance recorder to allow extraction of the stored records.

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