Phoenix REL-IR2/REL-IR/REL-FO Series Industrial Relays Selection Guide

Opening: Versatile Relay Solutions for Industrial Control, Isolation & Delay Applications

The Phoenix REL-IR2/REL-IR/REL-FO series represents industrial-grade electromechanical relays tailored for diverse control scenarios—from dual-relay integration (REL-IR2) and standard industrial switching (REL-IR) to fiber-optic isolated control (REL-FO). Covering a wide input voltage range (12V DC–230V AC), multi-contact configurations (2×21/4×21 changeover contacts), and specialized features (latch, delay, manual reset, LED indication), these relays are engineered for industrial automation, process control, high-voltage isolation, and region-specific compliant applications (Australian AU certification, multi-standard MS certification). With industrial-grade durability, flexible functionality, and seamless system integration, they ensure reliable switching in harsh industrial environments while meeting global regulatory requirements.

I. Core Advantages of the Series

1. Multi-Series Functional Diversification

   • REL-IR2 Series: Dual-relay integrated modules (2×21 contacts) for space-saving dual-circuit control, ideal for compact control cabinets and redundant systems;
   • REL-IR Series: Single-relay modules with 2×21/4×21 contacts, supporting delay (LDP/LDM), latch (BL/L), and standard (L) functions for versatile industrial switching;
   • REL-FO Series: Fiber-optic isolated relays for high-voltage isolation and EMI-immune control, suitable for critical systems requiring optical signal transmission;
   • Wide Voltage Compatibility: DC (12V/24V/48V/125V/220V) and AC (24V/120V/230V) input options, matching diverse control system power supplies.

2. Industrial-Grade Reliability & Environmental Adaptability

   • Wide operating temperature range (-40°C to +85°C), resistant to extreme cold, heat, and humidity in factory floors and outdoor auxiliary equipment;
   • Robust contact design: Up to 10⁷ mechanical operations and 10⁶ electrical switching cycles (at rated load), ensuring long service life in 24/7 operations;
   • High insulation voltage (≥4kV) between coil and contacts, providing safe isolation for high-voltage control circuits;
   • EMC compliance with IEC 61000-6-2/4, suppressing electromagnetic interference from inverters, motors, and power lines.

3. Specialized Functional Design & Compliance

   • Function Suffixes:
     • BL/L = Block + Latch (with LED indication);
     • LDP = Latch Delay Push (delay + latch, push-button reset);
     • LDM = Latch Delay Manual (delay + latch, manual reset);
     • LD = Latch Delay;
     • L = Standard Latch;
   • Certifications: AU (Australian AS/NZS compliance) for local market projects, MS (multi-standard) for global cross-border applications;
   • Safety Features: LED status indicators for real-time switching monitoring, manual reset options for fault recovery, and reverse polarity protection (DC variants).

4. Easy Installation & System Integration

   • DIN rail (NS 35/7.5) snap-in mounting, compatible with control cabinet infrastructure for quick deployment;
   • Compact design (17.5mm/module for REL-IR2, 22.5mm for REL-IR) saving valuable cabinet space;
   • Compatibility with industrial PLCs, HMIs, and sensors, supporting standard control signals (DC/AC) and fiber-optic inputs (REL-FO);
   • Plug-and-play wiring with clearly labeled terminals for error-free installation.

II. Product Classification & Detailed Parameter Table

The series is categorized by sub-series (REL-IR2, REL-IR, REL-FO) with sub-variants based on input voltage, contact configuration, functional suffix, and certifications.

1. REL-IR2 Series (Dual-Relay Integrated Modules)

Dual-relay modules with 2×21 changeover contacts, ideal for compact dual-circuit control.

2. REL-IR Series (Standard Industrial Relays)

Single-relay modules with 2×21/4×21 contacts, supporting delay, latch, and manual reset functions.

3. REL-FO Series (Fiber-Optic Isolated Relays)

Fiber-optic controlled relays for high-isolation, EMI-immune applications.

III. Nomenclature Decoding: Understanding the Part Number System

1. REL-IR2 Series

REL-IR2-[Function Suffix]-[Input Voltage]/[Contact Configuration]

• REL: Product series identifier (industrial electromechanical relay);
• IR2: Dual-relay integrated module (IR = Industrial Relay, 2 = Dual);
• Function Suffix:
  • BL/L = Block + Latch (with LED indication);
  • LDP = Latch Delay Push (delay + latch, push-button reset);
  • L = Standard Latch;
• Input Voltage: 24DC/120AC/230AC, etc. (DC=Direct Current, AC=Alternating Current);
• Contact Configuration: 2X21 = 2 groups of changeover contacts (SPDT: 1NO + 1NC per group).

2. REL-IR Series

REL-IR-[Function Suffix]-[Input Voltage]/[Contact Configuration]-[Certification]

• REL-IR: Standard industrial relay (single-relay module);
• Function Suffix:
  • LDP = Latch Delay Push;
  • LDM = Latch Delay Manual;
  • L = Standard Latch;
• Input Voltage: 12DC/24DC/48DC/125DC/220DC/120AC/230AC, etc.;
• Contact Configuration: 2X21 (2 groups SPDT) / 4X21 (4 groups SPDT);
• Certification: AU (Australian certification) / (no suffix = standard).

3. REL-FO Series

REL-FO-[Function Suffix]-[Input Voltage]/[Contact Configuration]-[Certification]

• REL-FO: Fiber-optic isolated relay (FO = Fiber Optic);
• Function Suffix: LD (Latch Delay) / L (Standard Latch);
• Input Voltage: 24DC (fiber-optic controlled, input voltage refers to relay coil power);
• Contact Configuration: 2X21 = 2 groups SPDT;
• Certification: MS (multi-standard compliance).

IV. 3-Step Quick Selection Technique

Step 1: Select Sub-Series Based on Functional Needs

• Dual-circuit control (space-saving): Choose REL-IR2 series (e.g., 2906302/2903660) for compact dual-relay integration.
• Standard single-circuit/multi-circuit control: Opt for REL-IR series (e.g., 2834096/2834148) with 2×21/4×21 contacts.
• High-isolation/EMI-immune control: Pick REL-FO series (1308298/1308296) for fiber-optic signal transmission.
• Australian market projects: Select AU-certified variants (e.g., 2834096/2834148) to meet local regulatory requirements.

Step 2: Match Input Voltage & Contact Configuration

• Input Voltage: Verify control system voltage (DC/AC) and select matching variants:
  • Low-voltage DC (12V/24V): 2834083/2906302 (24DC);
  • Medium-voltage DC (48V/125V): 2834106/2903664 (125DC);
  • High-voltage DC (220V): 2834973/2903665 (220DC);
  • AC (24V/120V/230V): 2903666 (24AC)/2903667 (120AC)/2906303 (230AC).
• Contact Configuration:
  • 2-group loads (e.g., dual actuators): 2X21 variants (2906302/2834070);
  • 4-group loads (e.g., quad sensors/actuators): 4X21 variants (2834096/2834148).

Step 3: Choose Function Suffix for Control Logic

• Latch control with LED indication: Select BL/L suffix (2906302/2906303) for visual status monitoring.
• Delay + latch (push-button reset): Opt for LDP suffix (2834096/2903660) for sequential control with automatic reset.
• Delay + latch (manual reset): Pick LDM suffix (2834216) for emergency or fault-tolerant systems.
• Standard latch (no delay): Choose L suffix (2903668/2834135) for basic on/off latch control.
• Fiber-optic isolation: Select REL-FO series (1308298/1308296) for high-EMI environments.

V. Recommended Industry-Scenario Combinations

VI. Selection Pitfall Avoidance Guide

1. Voltage Mismatch: Using 230V AC relays for 24V DC control systems → Verify input voltage and select matching variants (e.g., 2906302 for 24DC) to prevent coil burnout.
2. Australian Certification Neglect: Using non-AU relays for local projects → Choose AU-suffix models (2834096/2834148) to avoid regulatory non-compliance.
3. Contact Configuration Insufficiency: Using 2X21 relays for 4-group loads → Select 4X21 variants (2834096/2834135) to avoid wiring complexity.
4. Function Suffix Misunderstanding: Requiring manual reset but using LDP (push-button reset) relays → Choose LDM suffix (2834216) for manual reset functionality.
5. High-EMI Environment Using Standard Relays: Experiencing signal interference in power systems → Opt for REL-FO series (1308298/1308296) for fiber-optic isolation.
6. Space Constraints Using Single Relays: Using multiple single relays in compact control cabinets → Select REL-IR2 dual-relay modules (2906302) to save space.
7. Delay Control Need Using Standard Latch Relays: Requiring sequential control with delay but using standard L relays → Choose LDP/LD suffix variants (2903660/1308298) for delay functionality.
8. High-Voltage Isolation Neglect: Using low-isolation relays for 220V DC circuits → Select high-insulation variants (2834973/2903665) with ≥4kV isolation.

Conclusion: Select the Right REL Relay for Precise Industrial Control

The Phoenix REL-IR2/REL-IR/REL-FO series delivers versatile, industrial-grade relay solutions for dual-circuit integration, standard switching, and fiber-optic isolated control. With wide voltage compatibility, multi-contact configurations, specialized functional features (latch/delay), and regional certifications (AU/MS), these relays meet the demands of industrial automation, power control, and critical process systems.