Phoenix Contact 2902879 Active DC Redundancy Module

QUINT-ORING/24DC/2X40/1X80

Product Overview

Active DC redundancy module (Oring module), DIN rail mount. Designed for parallel redundant power supply of two 24VDC power supplies. Adopts MOSFET active current balancing ACB technology to resolve the drawbacks of diode redundancy, such as large voltage drop and unbalanced current sharing. Widely used in industrial control cabinets, DCS and PLC critical power supply circuits. It enables seamless switching when one power supply fails to guarantee continuous power to loads.

Key Specifications

Working Principle

Two 24V power supplies connect to the two input channels respectively. The module automatically balances load current. If either power supply fails or loses power, the internal MOSFET isolates the faulty branch rapidly, and the healthy power supply continues to power the load. Monitoring contacts can send fault signals to upper-level PLC.

Typical Application Scenarios

Redundant power supply for DCS and safety instrumented systems in petrochemical, power generation and railway industries

Large-scale automated production lines and warehouse logistics control systems

Server rooms and security monitoring DC redundant power supply

Alternative Selection Reference

1. Lower-current model of the same series: 2902878 QUINT-ORING/24DC/2X20/1X40 (2×20A input, 40A output)
2. Alternative solution: Diode-type redundancy module (lower cost, but with voltage drop, not suitable for high-current precision power supply)

Troubleshooting Guidelines

1. Red LED alarm: Check single-channel input undervoltage, power supply failure or module overheating
2. Output voltage drop: Verify input wire gauge, tightening torque of terminals under high-current conditions; check heat dissipation clearance of the module
3. Current imbalance: The output voltages of the two power supplies must be calibrated consistently for normal ACB current sharing

Active MOSFET Oring Redundancy Module vs. Conventional Diode Redundancy Module

Conventional redundancy modules refer to diode-type passive redundancy modules, namely Phoenix QUINT-DIODE series. The 2902879 QUINT-ORING is an active MOSFET Oring module. The core differences are listed below:

1. Core Components & Voltage Drop (Most Critical Difference)

Active Oring (MOSFET)

Internally uses controlled MOSFET switches; conduction drop at tens of millivolts, nearly negligible, efficiency up to 98%.

Low heat generation under high-current operation. No need to deliberately raise power supply output voltage to compensate for voltage drop.

Conventional Diode Redundancy (Passive)

Relies on Schottky diodes for unidirectional conduction; voltage drop of 0.3~0.4V.

High power dissipation and heat generation at 80A. Engineers must increase the power supply output by ~0.4V for compensation, otherwise load-side voltage will be insufficient.

2. Load Current Sharing (ACB Automatic Current Balance)

Active Oring (e.g. 2902879)

Equipped with ACB automatic current balance technology. Two power supplies share the load current equally. Both power supplies carry load continuously, extending service life. Not a setup where one unit runs at full load while the other stands by.

Diode Redundancy

No active current sharing. The power supply with slightly higher output voltage takes most of the load, while the other remains almost unloaded. One unit ages faster in long-term operation; it is a hot standby scheme without load sharing.

3. Monitoring, Alarm & Diagnostics

Active Oring

Continuously monitors two input voltages and MOSFET decoupling circuit status. Relay alarm contacts are available to report faults: loss of single power supply, module overheating, decoupling circuit failure, OVP overvoltage clamping (limits maximum output voltage to protect PLC/DCS cards). It provides early warning of lost redundancy for maintenance replacement before dual faults cause shutdown.

Diode Redundancy

Pure passive hardware with no monitoring or alarm signals. If one power supply fails, the system remains powered, but the loss of redundancy cannot be detected until the second power supply also fails and causes outage.

4. Fault Isolation Speed

Active Oring: MOSFET turns off in microseconds. Reverse current is detected and the faulty branch is cut off immediately to prevent the failed power supply from pulling down the output bus.

Diode Redundancy: Passive blocking via inherent diode unidirectional characteristic; response depends on diode properties.

5. Cost, Reliability & Application Scope

Active Oring (2902879 type)

✅ Advantages: Low voltage drop, low heat generation, automatic current sharing, fault monitoring, overvoltage protection, high availability

❌ Disadvantages: More complex circuit, higher price, built-in control circuit

👉 Applications: DCS, SIS safety instrumented systems, power/petrochemical/railway industries, high-value production lines, critical high-current 24V power circuits where unexpected shutdown is prohibited.

Conventional Diode Redundancy Module

✅ Advantages: Simple structure, few components, stable reliability, low cost, no control circuit, suitable for explosion-proof environments

❌ Disadvantages: Large voltage drop, severe heat at high current, no current sharing, no fault alarm, heavy heat dissipation burden under high current

👉 Applications: Ordinary control cabinets, low/medium-current auxiliary circuits, projects with limited budget that only require basic anti-parallel reverse protection.

Comparison Table

Selection Recommendation

If current ≥40A, high shutdown loss is expected and remote redundancy status monitoring is required → Select active Oring such as 2902879

For low-current auxiliary circuits with limited budget, only basic anti-reverse parallel protection needed → Diode redundancy module is sufficient

Phoenix QUINT-ORING Active Redundancy Module Full Series List (ACB Auto Current Balancing MOSFET Oring, series of 2902879)

-Note: Distinguish QUINT-ORING (original standard version) / QUINT4-ORING (4th generation new version); `/CO` denotes conformal coated version (anti-corrosion for chemical plants and high-humidity environments)

1. QUINT-ORING (Original Series, fixed 24DC input, your model belongs here)

2. QUINT4-ORING (4th generation upgraded model, 12~24VDC wide input, new replacement)

3. Passive Diode Redundancy of the same platform (QUINT-DIODE, not part of ORING active series, for reference only)

-Passive diode redundancy, no ACB current sharing, no active MOSFET, do not confuse with ORING

2907719 QUINT4-DIODE/12-24DC/2X20/1X40

2320157 QUINT-DIODE/12-24DC/2X20/1X40

Series Selection Summary

1. QUINT-ORING (2902877/2902878/2902879): Fixed 24VDC input, ACB active current balancing, standard for industrial cabinets; `/CO` coated variant for chemical, offshore and highly corrosive environments.
2. QUINT4-ORING: 12~24VDC wide DC input, new generation hardware with optimized dimension and monitoring logic. Preferred for new projects.
3. Current ratings: 20A /40A /80A. Match rating according to rated current of the two power supplies.

Model Naming Breakdown (QUINT-ORING/24DC/2X40/1X80)

QUINT-ORING: QUINT series active redundancy Oring module

24DC: Rated input 24V DC

2X40: Two input channels, max. 40A per channel

1X80: Combined single output channel, max. 80A

/CO: Conformal Coating, anti-corrosion protective coating