Siemens 7SR242

7SR242 Duobias Description Of Operation
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©2010 Siemens Protection Devices Limited
7SR242 Duobias
Multi-Function 2-Winding Transformer Protection Relay
Document Release History
This document is issue 2010/06. The list of revisions up to and including this issue is:
2010/06 Additional Comms modules option of (RS485 + IRIG-B) and (RS232 + IRIG-B) and typographical
revisions
2010/02 Document reformat due to rebrand
2010/02 Third issue. Software revision 2662H80001 R4c-3
2008/07 Second issue. Software revision 2662H80001R3d-2c.
2008/05 First issue
Software Revision History
2010/02 2662H80001 R4c-3 Revisions to: VT ratio settings, 87BD 1
st
bias slope limit setting
increments, CB fail function, LED CONFIG menu, DATA
STORAGE menu.
Added: Open circuit detection (46BC), CONTROL MODE
menu, Close circuit supervision (74CCS), Measured earth fault
undercurrent (37G), Pulsed output contacts.
2008/07 2662H80001R3d-2c. Demand metering. Optional DNP3.0 data comms.
2008/05 2662H80001R3-2b First Release

Siemens 7SR242 Specifications

General

Brand	Siemens
Model	7SR242
Category	Relays
Language	English

Summary

Document Release History

Software Revision History

Symbols and Nomenclature

Section 1: Introduction

General Safety Precautions

Important safety notes regarding CT circuits, external resistors, fibre optics, and front cover usage.

Section 2: Hardware Description

Relay Architecture and Case

Details the relay's modular structure, case dimensions, and panel fitting.

Operator Interface and Controls

Covers the front fascia, display, buttons, and information labels for user interaction.

InputOutput Interfaces

Describes current/voltage inputs, binary inputs/outputs, and their configurations.

Self-Monitoring and Virtual IO

Explains relay self-monitoring features and the use of virtual input/output states.

Section 3: Protection Functions

Current Protection Functions

Covers differential, overcurrent, earth fault, undercurrent, and thermal overload protections.

Voltage Protection Functions

Details overfluxing, under/over voltage, and neutral overvoltage protection elements.

Frequency Protection Functions

Explains under/over frequency detection capabilities.

Section 4: Control & Logic Functions

Quick Logic Functionality

Describes inputting and using logic equations for control and automation.

Section 5: Supervision Functions

Circuit Breaker Failure Protection

Explains the circuit breaker fail supervision element and its outputs.

TripClose Circuit Supervision

Details supervision elements for trip and close circuits.

Inrush and Overfluxing Detectors

Covers the inrush detector (81HBL2) and overfluxing detector (81HBL5).

Demand Monitoring

Explains how maximum, minimum, and mean demand values are recorded and managed.

Section 6: Other Features

Data Communications and Maintenance

Details communication ports, protocols, software, and maintenance tests like output matrix and CB wear.

Data Storage and Fault Records

Explains storage of event, waveform, and fault records, including buffer management.

Metering, Operating Modes, and Clock

Covers real-time metering, operating modes (Local, Remote, Service), and clock settings.

Settings Groups and Password Protection

Describes managing settings groups and the relay's password protection features.