7S.16.9.024.5420T Finder Relay module DC 24V 4NO2 NC

Why Choose the Finder 7S.16.9.024.5420T Railway Safety Relay?

The Finder 7S.16.9.024.5420T is a professional 24 V DC railway safety relay module featuring six forcibly guided contacts, designed for railway equipment, industrial automation and safety-related electrical control systems. Part of the Finder 7S Series, this modular electromechanical relay provides a 4 normally open (NO) + 2 normally closed (NC) contact configuration, a 6 A rated contact current and compact DIN rail installation.

The distinguishing feature of the Finder 7S.16.9.024.5420T is its railway-specific T version, developed for applications requiring resistance to vibration, mechanical shock and demanding environmental conditions. The railway version is designed with reference to EN 50155, EN 61373 and EN 45545-2, making it particularly relevant to railway rolling stock and associated electrical control equipment.

Its Class A forcibly guided contacts, designed in accordance with EN 61810-3, allow external monitoring circuits to detect specified contact failures. Combined with a 24 V DC coil, integrated LED coil status indication, screwless terminals and a 22.5 mm-wide housing, this relay provides a practical solution for engineers developing monitored switching circuits in railway and industrial environments.

Key Advantages

• Railway-specific T version designed for demanding rolling stock applications.
• Six forcibly guided contacts support reliable switching and external fault monitoring.
• 4 NO + 2 NC contact configuration provides four switching contacts and two feedback contacts.
• 24 V DC nominal coil voltage for compatible railway and industrial control supplies.
• 6 A rated contact current for suitable control and signalling loads.
• Class A mechanically linked contacts in accordance with EN 61810-3.
• EN 50155 railway environmental design for temperature and humidity conditions.
• EN 61373 vibration and shock resistance for railway applications.
• EN 45545-2 fire protection requirements addressed through railway-suitable materials.
• Integrated LED coil status indication assists commissioning and fault finding.
• Screwless spring-clamp terminals support efficient electrical installation.
• 22.5 mm module width helps conserve space in compact electrical cabinets.
• 35 mm DIN rail mounting enables straightforward integration.
• Suitable for use in appropriately engineered SIL 2 safety-related systems, subject to complete system assessment.

Key Features

• Finder 7S Series modular relay with forcibly guided contacts.
• T railway version for rail transport applications.
• Six-pole contact arrangement: 4 NO + 2 NC.
• Class A forcibly guided contact construction.
• 24 V DC nominal coil voltage.
• 16.8–30 V DC coil operating range.
• 6 A rated contact current.
• 250 V AC nominal switching voltage.
• 1,500 VA AC-1 rated switching capacity.
• Gold-plated silver-alloy contacts for the specified relay construction.
• 12 ms typical operate time.
• 10 ms typical release time.
• Integrated LED indicating coil energisation.
• Monostable, non-latching operation.
• Screwless spring-clamp terminals.
• 35 mm DIN rail mounting according to EN 60715.
• IP20 protection rating.
• Railway shock and vibration resistance to EN 61373 Category 1, Class B.
• Railway temperature and humidity classification to EN 50155 OT4/ST1.
• Railway fire protection material requirements according to EN 45545-2:2020.

Railway-Specific Design for Demanding Operating Conditions

The Finder 7S.16.9.024.5420T is specifically intended for applications where electrical equipment must withstand the environmental demands of railway service. Unlike a conventional industrial relay, the T railway version incorporates design characteristics intended for use in rolling stock electrical installations.

The relay's railway-related specifications include EN 50155 for electronic equipment used on railway rolling stock, EN 61373 for resistance to vibration and mechanical shock, and EN 45545-2 for fire protection requirements relating to materials and components. These characteristics make the device suitable for consideration in railway control cabinets, signalling interfaces and onboard electrical systems.

Its 24 V DC coil operates over a specified range of 16.8–30 V DC, helping accommodate voltage variations within compatible low-voltage control supplies. The exact supply arrangement and protective measures must be assessed against the requirements of the railway installation.

The relay also features a compact 22.5 mm DIN rail housing and screwless terminals, allowing integration into space-constrained railway equipment cabinets. Its integrated LED provides a convenient visual indication of coil energisation during commissioning and maintenance.

How Forcibly Guided Contacts Support Fault Detection

The Finder 7S.16.9.024.5420T uses Class A forcibly guided contacts to support reliable monitoring of electromechanical switching operations. Its four normally open and two normally closed contacts are mechanically linked, creating a defined relationship between their operating positions.

If a normally open contact becomes welded closed, the mechanical guidance prevents the normally closed contacts from returning to their closed positions. This allows a suitably designed external monitoring circuit to identify an abnormal contact condition and initiate the appropriate response.

The 4 NO + 2 NC arrangement is particularly useful where several independent switching paths are needed alongside feedback contacts. For example, the normally open contacts may be used in appropriate control or enable circuits, while the normally closed contacts provide diagnostic feedback to a safety controller.

The relay can be used as a component within systems designed to achieve SIL 2 or Performance Level d. However, these ratings apply to the complete assessed safety function rather than to the relay alone. System architecture, diagnostic coverage, reliability calculations and validation remain essential.

Typical Applications

• Railway rolling stock electrical control systems.
• Train control and onboard automation equipment.
• Railway control cabinets and electrical panels.
• Rail vehicle auxiliary control circuits.
• Railway equipment requiring vibration-resistant relay components.
• Rail transport systems requiring monitored switching contacts.
• Safety PLC output and feedback interfaces.
• Industrial machinery safety-related control circuits.
• Machine guarding and interlocking systems.
• Emergency-stop control architectures with external monitoring.
• Industrial automation and manufacturing equipment.
• Conveyor and material-handling control systems.
• Applications requiring four normally open contacts and two normally closed feedback contacts.