Safety Relays

Part Number	Description / PDF	Quantity
2903255 Phoenix Contact	PSR-SPP-24DC/MXF2/4X1/2X2/B	0
56.OA69.2411C Altech Corporation	OA566924V 1NO/1NC AGSN02+02UMAU	0
56.OA42.2411C Altech Corporation	OA5642 24VDC1NO/1NC CONTACTS AGS	0
7S.63.9.024.0211 Finder Relays, Inc.	SFTY RLY GUIDE 2NO+1NC 6A 24VDC	0
56.OA43.1221S Altech Corporation	OA5643 12VDC2NO/1NC CONTACTS AGN	0
56.OA21.2431C Altech Corporation	OA5621 24VDC3NO/1NC CONTACTS AGS	100
256.OA11.1222C Altech Corporation	2 CHANNEL MODULE 4P8A 12V 2NO/2N	0
56.OA21.2422N Altech Corporation	OA5621 24VDC2NO/2NC CONTACTS AGN	0
V23050A1048A551 TE Connectivity Potter & Brumfield Relays	RELAY SAFETY	0
56.OA69.2000S Altech Corporation	OA566920V 2CO AGNI10+5UMAU IP40	0
56.OA11.2431S Altech Corporation	OA561124V 3NO/1NC AGNI10+5UMAU I	0
56.OA12.2424S Altech Corporation	OA561224V 2NO/4NC AGNI10+5UMAU I	0
56.OA01.0631N Altech Corporation	OA5601 6V 3NO/1NC AGNI10+2UMAU I	0
8927.3N Altech Corporation	SAFETY RELAY 24V DPDT BUSSED CON	0
56.OA70.2431N Altech Corporation	OA5670 24VDC3NO/1NC CONTACTS AGN	0
56.OA22.2442C Altech Corporation	OA5622 24VDC4NO/2NC CONTACTS AGS	0
7S.14.8.120.4220 Finder Relays, Inc.	SFTY RLY GUIDE 2NO+2NC 6A 120VAC	0
256.OA02.1224C Altech Corporation	2 CHANNEL MODULE 6P10A 12V 2NO/4	0
56.OA44.0631C Altech Corporation	OA5644 6VDC3NO/1NC CONTACTS AGSN	0
56.OA44.1122S Altech Corporation	OA5644 110VDC2NO/2NC CONTACT AGN	0

Safety Relays

1. Overview

Safety relays are specialized control devices designed to ensure fail-safe operation in industrial systems. They monitor safety-related inputs (e.g., emergency stops, light curtains) and trigger protective actions by cutting power to machinery. Compliant with international standards like IEC 61508 and ISO 13849-1, these relays form the backbone of safety instrumented systems (SIS) across automation sectors.

2. Major Types and Functional Classification

Type	Functional Characteristics	Application Examples
Electromagnetic Safety Relays	Mechanical contact-based design with physical separation	Machinery emergency stops, simple safety circuits
Solid-State Safety Relays	Zero-contact semiconductor switching with vibration resistance	Precision equipment, explosive atmosphere environments
Programmable Safety Relays	Configurable logic with diagnostic capabilities	Robotic cells, complex safety interlocking systems
Monitoring Safety Relays	Continuous circuit integrity verification	Safety door interlocks, two-hand control systems

3. Structure and Components

Typical safety relay construction includes:

Enclosure: Flame-retardant polymer housing (UL94 V-0 rated)
Coil System: 24V DC/AC operating with bifilar winding for failure detection
Contact Arrangement: Gold-plated contacts with positive-guided mechanism
Diagnostic Circuitry: Built-in semiconductor for contact state monitoring
Mounting Options: DIN rail or PCB mount with screw/clamp terminal connections

4. Key Technical Parameters

Parameter	Typical Value	Importance
Safety Integrity Level (SIL)	SIL 3 (IEC 61508)	Determines risk reduction factor
Response Time	5-50 ms	Affects machine safe stop performance
Contact Rating	6A @ 250V AC	Dictates load switching capability
MTBF	500,000 hours	System uptime prediction
Environmental Temp	-20 C to +55 C	Operational reliability factor

5. Application Areas

Primary industries include:

Industrial Automation: CNC machines, assembly lines
Energy Systems: Wind turbine safety circuits
Transportation: Rail vehicle door control systems
Medical Equipment: MRI machine emergency cutoffs

Case Study: Automotive Press Line Safety

A major automotive manufacturer implemented safety relays in 1200-ton press machines, achieving PLc (EN ISO 13849-1) compliance through dual-channel emergency stop circuits with 35ms response time.

6. Leading Manufacturers and Products

Manufacturer	Representative Product	Key Features
Siemens	3SK1 Safety Relay	Modular design, PROFINET integration
Schneider Electric	XPSM Safety Relay	Multi-sensor monitoring, SIL3 capable
Omron	G9SP-N Safety Controller	Programmable with 30 pre-defined safety functions
Phoenix Contact	PSR-SCP-24DC-PO Safety Relay	Plug-in module with status visualization

7. Selection Guidelines

Critical selection factors:

Safety Category: Match to application risk assessment (Cat. 2/3/4)
Environmental Conditions: Consider temperature, vibration, and EMC
Certifications: Required standards (CE, UL, T V)
Expansion Capability: Future system scalability
Diagnostic Coverage: Minimum 90% recommended

8. Industry Trends

Emerging developments include:

Integration with Industry 4.0 through IO-Link interfaces
Functional safety for collaborative robots (cobots)
Wireless safety communication protocols
Miniaturization while maintaining IP67 ratings
AI-enhanced predictive maintenance capabilities