Intelligent Fault Strategy for DIN Rail Power Supplies

RECOM RACPRO Electronic Safety Modules for Industrial Plants

Channel protection with switch-mode design: 24V DIN rail enclosures contain essential power supplies and electronic fuses for a wide range of industrial applications. Power supply quality and reliability are essential system features. However, it is not only the failure of individual power sources that requires protection. Equally important is preventing a fault in one device from affecting the rest of the enclosure. Faults within the system must not compromise the stability of the entire enclosure.

Two RECOM DIN-rail power supplies mounted on a rail against an industrial factory backdrop, their green front-panel LEDs indicating active status monitoring — the kind of intelligent fault diagnostics built into the REC-N series for reliable operation on the factory floor.

DIN Rail Power Supplies in Direct Comparison
RECOM’s Intelligent Fault Correction Strategy
Summary: System Stability in Control Cabinets

In conjunction with the RACPRO1-4SP/24 series electronic fuses, the customer can design a control cabinet that ensures proper system stability in the event of serious faults in individual loads. However, when selecting electronic fuses, the customer must consider several criteria that are essential for reliable system stability.

These include investigations into the start-up conditions under various load states, short circuits, and high capacitive loads, which are often overlooked. This report describes the extent to which the RACPRO1-4SP/24 series electronic fuses ensure the system stability of the control cabinet application compared to selected competitor products.

DIN Rail Power Supplies in Direct Comparison

RECOM compared its RACPRO1 series DIN rail power supplies and electronic fuses with those of two other leading manufacturers (referred to as Manufacturer A and Manufacturer B). The tests included start-up conditions with short circuits, overloads, and capacitive loads.

Performance During a Short Circuit

Without adequate protection, short circuits can lead to chain reactions and system-wide malfunctions throughout the entire control cabinet.

Ripple at the power supply outputs in the oscilloscope image

Figure 1: The devices from manufacturer A exhibited ripple at all outputs.

In direct comparison tests, RECOM found that a short circuit in a cabinet containing equipment from manufacturer A resulted in voltage spikes and ripple on all outputs. RECOM’s e-Fuse isolates the affected channel without affecting the behavior of the other channels.

Oscilloscope image showing a voltage drop

Figure 2: The devices from manufacturer B experienced a complete voltage drop.

The same test with devices from manufacturer B resulted in a complete voltage drop, causing all channels to fail. After repeated incidents, one channel was permanently damaged.

The oscilloscope indicates an isolated channel fault.

Figure 3: With the RECOM RACPRO1, there were only effects on the affected channel.

Figure 3: With the RECOM RACPRO1, there were only effects on the affected channel.

The RECOM RACPRO1-4SP/24 isolated the fault. Only the affected channel was switched off; the other channels showed neither voltage drop nor ripple.

Overload Protection Performance

In this test series, an overload fault was simulated on a 20A power supply by applying an 8A load to each of four outputs, resulting in a total of 32A. The outputs of the RACPRO1-4SP/24 devices are factory-prioritized so that an overload condition only affects the lowest-priority output.

However, the highest-priority channel can also be shut down if an overload occurs that causes a voltage drop in the input. Before this happens, however, an attempt is made to stabilize the power supply by shutting down the lower-priority channels. The RACPRO1-4SP/24 device actively manages the power supply instead of reacting unpredictably, thus reducing downtime and preventing unpredictable machine behavior.

Neither manufacturer A nor manufacturer B offers channel prioritization. Under these test conditions, both produced the same result: an unpredictable failure in which random channels were shut down.

Capacitive Starting Current and Inrush Current

Capacitive loads can cause high inrush currents when switched on. Without protection against high inrush currents, power supplies can deliver a poorly regulated output voltage, fail due to overload, or blow the fuse. The RACPRO1-4SP/24 operates in true constant current mode, which regulates the inrush load. The RACPRO1-4SP/24 can handle up to 4mF per Ampere with a sequential turn-on delay of up to 100ms.

The capacitive load test included a 40mF capacitance with an additional 10A load. Under these test conditions, the RACPRO1-4SP e-Fuse ensured a smooth start-up without affecting other channels.

Gentle voltage increase without disturbances

Figure 4: The gentle voltage increase of the RACPRO1 caused no interference on other channels.

The RACPRO1 delivers a linear voltage increase without exceeding the current limits of the power supply.

Power outage with severe ripple

Figure 5: The devices from manufacturer A exhibited failures or severe ripple.

The devices from manufacturer A exhibited strong ripple throughout the entire inrush load phase; the devices from manufacturer B failed even at low capacitive loads.

RECOM’s Intelligent Fault Correction Strategy

Hiccup protection timing with increasing time intervals up to 6.4s

Figure 6: Simple daisy-chaining and load wiring

The fault strategy integrated into RECOM’s RACPRO1 minimizes thermal stress, prevents fault propagation across multiple channels, and ultimately increases system stability.

Its three pillars are:

Immediate isolation of short circuits
Priority-based shutdown in case of overload
Adaptive restart in hiccup mode with increasing time intervals up to 6.2s

Furthermore, the true constant current design prevents operating conditions such as high capacitive inrush loads from causing a fault. The modules can be connected in series or configured for sequential start-up, making RACPRO1 a fundamental building block for stable, scalable control cabinet architectures.

Comparison of power distribution on DIN rails with simplified series connection and reduced wiring complexity

Figure 7: Simple daisy chaining and load cabling

Summary: System Stability in Control Cabinets

The RACPRO1-4SP/24 series products feature dedicated current control in each channel, thus fulfilling far more than the function of a simple e-fuse; they operate as intelligent power distribution units designed for predictable and reliable system behavior. With constant current starting, channel prioritization, guaranteed selectivity, and true fault isolation between channels, the RACPRO1-4SP/24 series ensures that every load performs its function without any operational limitations.

This article was originally published by RECOM.

Products & Services

source= https://railway-news.com/din-rail-intelligent-fault-strategy-for-din-rail-power-supplies/

Intelligent Fault Strategy for DIN Rail Power Supplies

RECOM RACPRO Electronic Safety Modules for Industrial Plants

Table of Contents