Phoenix Contact QUINT-PS-1AC-24DC-5 Retrofit-Ready PSU

Phoenix Contact QUINT-PS-1AC-24DC-5 Retrofit-Ready Power Supply for Legacy Control Systems

The Phoenix Contact QUINT-PS-1AC-24DC-5 is a 24 VDC / 5 A single-phase DIN rail power supply engineered for demanding industrial environments. As legacy automation systems reach end-of-life and OEM support is discontinued, this unit has become one of the most sought-after retrofit and replacement components across PLC-based control architectures. Whether you are upgrading a Siemens S7-300 control cabinet, replacing a failed PSU in a Schneider Electric Modicon M340 rack, or restoring power integrity to an Allen-Bradley ControlLogix chassis, the QUINT-PS-1AC-24DC-5 delivers the stable 24 VDC bus voltage that field devices, I/O modules, and communication gateways depend on.

With a wide-range AC input (85–264 VAC), active power factor correction, and QUINT’s signature SFB (Selective Fuse Breaking) technology, this power supply can replace older, non-SFB units without requiring changes to the downstream wiring topology. The unit mounts on standard 35 mm DIN rail and occupies a 45 mm panel width — a footprint that is directly compatible with most legacy control cabinet layouts. Output terminals accept conductors up to 10 mm², ensuring that existing field wiring can be reused without re-termination.

In retrofit projects involving Siemens ET 200S distributed I/O stations or Beckhoff EtherCAT terminal blocks, maintaining a clean 24 VDC supply rail is critical. Voltage ripple or transient dips can cause communication faults on PROFIBUS DP segments or EtherCAT frames, leading to nuisance trips and unplanned downtime. The QUINT-PS-1AC-24DC-5 provides a regulated output with less than 50 mV ripple, making it suitable as a direct replacement for aging PSUs in these architectures.

For systems using Phoenix Contact’s own INTERBUS or PROFINET IO infrastructure — including IB IL 24 DI 8 digital input modules, IB IL 24 DO 8 digital output modules, or FL SWITCH managed Ethernet switches — the QUINT-PS-1AC-24DC-5 is the factory-recommended power source. Its signaling relay output allows integration with the PLC’s diagnostic input, enabling the controller to detect impending power failure and execute a controlled shutdown sequence before process data is lost.

When migrating from older TRIO-PS or MINI-PS series supplies, engineers should verify the load current budget across all 24 VDC consumers in the cabinet — including solenoid valves, relay coils, HMI panels such as the Phoenix Contact TP 3057T, and any 24 VDC-powered communication modules. The QUINT-PS-1AC-24DC-5’s 5 A continuous rating, combined with its 125% static boost capability, provides headroom for inrush currents during cabinet power-up sequences without nuisance tripping.

Upgrade Compatibility Table

Retrofit Planning for Existing Automation Systems

A successful retrofit begins with a thorough audit of the existing control cabinet’s power distribution architecture. Before removing the failed or end-of-life PSU, document the current output voltage setpoint, the DC OK relay wiring path, and the total connected load in amperes. In cabinets housing Siemens S7-300 CPU modules alongside SM 321 digital input cards and SM 322 digital output cards, the 24 VDC bus typically supplies both the backplane logic and the field-side I/O simultaneously. Confirm that the QUINT-PS-1AC-24DC-5’s 5 A output is sufficient for the combined load, accounting for any CP 343-1 PROFINET communication processors or IM 360/361 interface modules that draw additional current.

In Schneider Electric Modicon architectures, the 24 VDC supply feeds BMX DDI 1602 digital input modules and BMX DDO 1602 digital output modules mounted on the BMX XBP backplane. When replacing the PSU in these systems, ensure the new unit’s output terminals are connected to the same bus bar arrangement and that the DC OK signal is routed to a spare BMX DDI input channel for supervisory monitoring. For systems using a TSX Premium rack with TSX PSY 2600M power supplies, the QUINT-PS-1AC-24DC-5 can serve as a supplementary 24 VDC source for field devices while the rack PSU continues to power the backplane.

Communication module integrity is another critical consideration. FL SWITCH 8TX managed switches, PROFIBUS DP repeaters, and Modbus RTU gateways all require a stable 24 VDC supply. Any voltage sag during PSU replacement can cause these devices to reboot, dropping active communication sessions and potentially triggering PLC fault states. Plan the replacement during a scheduled maintenance window and use a temporary UPS or battery-backed supply to bridge the 24 VDC bus during the changeover.

HMI panels — including Phoenix Contact TP 3057T or third-party panels connected via RS-232 or Ethernet — should be powered down gracefully before the PSU is removed. Abrupt power loss to an HMI can corrupt the runtime project stored in flash memory, requiring a full project reload from the engineering workstation. After installing the QUINT-PS-1AC-24DC-5, power up the HMI first, verify the display initializes correctly, and then restore power to the PLC rack and field devices in sequence.

Downtime Control During System Migration

Minimizing unplanned downtime during a PSU retrofit requires a structured changeover procedure. Begin by exporting the current PLC program from the CPU — whether a Siemens S7-300, Allen-Bradley CompactLogix, or Mitsubishi MELSEC Q-series controller — to a laptop running the appropriate engineering software (STEP 7, Studio 5000, or GX Works2). Store the backup on both the laptop and a USB drive kept at the panel. This ensures that if the CPU loses its program during power cycling, recovery takes minutes rather than hours.

Next, place the PLC in STOP mode and notify all operators that the control system will be temporarily offline. Switch off the AC input to the existing PSU using the cabinet’s main isolator, then disconnect the DC output terminals, the DC OK relay wiring, and the PE ground connection in that order. Install the QUINT-PS-1AC-24DC-5 on the DIN rail, reconnect the terminals in reverse order, and restore AC power. Measure the output voltage at the bus bar before reconnecting field devices — adjust the output potentiometer if necessary to match the legacy setpoint.

Once the output voltage is confirmed stable, restore power to field devices and communication modules. Place the PLC back in RUN mode and monitor the first scan for any I/O fault flags. Verify that all PROFIBUS DP slaves or PROFINET IO devices have re-established communication by checking the diagnostic buffer in the engineering software. Document the completed retrofit with a timestamped entry in the cabinet’s maintenance log, noting the replaced part number, the new unit’s serial number, and the output voltage setpoint used.

All units supplied by SMARTNEXMSK are covered by a 12-month warranty from the date of shipment and include a functional test certificate confirming output voltage, current regulation, and DC OK relay operation prior to dispatch.

Retrofit Support FAQ

Q1: Is the QUINT-PS-1AC-24DC-5 a direct replacement for the TRIO-PS-1AC-24DC-5?
Yes. Both units share the same 24 VDC / 5 A output rating and 35 mm DIN rail mounting. The QUINT-PS-1AC-24DC-5 adds SFB technology and a DC OK signaling relay not present on the TRIO-PS series. Terminal pitch and cabinet depth are identical, allowing a 1:1 physical swap. Verify the DC OK relay wiring if your system uses the TRIO-PS’s signaling output.

Q2: Will the existing field wiring need to be re-terminated?
In most cases, no. The QUINT-PS-1AC-24DC-5 accepts conductors up to 10 mm² on its output terminals, which covers the majority of legacy wiring gauges used in 24 VDC distribution. If the existing installation uses ferrule-terminated conductors, they can be reused directly. Inspect the insulation condition of all conductors before reconnection and replace any that show signs of heat damage or brittleness.

Q3: How do I verify compatibility with my PROFIBUS DP or PROFINET IO system?
The QUINT-PS-1AC-24DC-5 is a standalone power supply with no embedded fieldbus interface. Compatibility is determined by its output voltage (24 VDC) and current capacity (5 A), not by communication protocol. Confirm that the total 24 VDC load of all connected PROFIBUS DP slaves, PROFINET IO devices, and field instruments does not exceed 5 A. If the load exceeds this threshold, consider paralleling a second QUINT-PS-1AC-24DC-5 using a Phoenix Contact redundancy module.

Q4: What does the 12-month warranty cover, and what is included at shipment?
The 12-month warranty covers manufacturing defects and functional failures under normal operating conditions. Each unit shipped by SMARTNEXMSK includes a functional test certificate documenting output voltage accuracy, load regulation performance, and DC OK relay continuity. Units are packed in anti-static packaging with original or equivalent documentation. Warranty claims are processed within 5 business days of receipt of the returned unit.

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