Achieving Power Reliability with coordinated surge protection and power supply components

Modern energy and automation systems demand a stable, efficient, and fail‑safe power supply. As a full‑service provider of high‑performance power supply systems, intelligent protection components, and coordinated device protection solutions. Phoenix Contact offers a comprehensive portfolio for Power Reliability. This approach goes beyond traditional power supply concepts and focuses on ensuring high system availability.

A reliable power supply system protects itself against all types of faults, from transient overvoltages and mains interruptions to voltage dips, overloads, and short‑circuits at the device level. Only the coordinated interaction of surge protection, power supplies, and modular device protection ensures a consistently stable supply. This system‑level approach reflects the Power Reliability concept. Its benefits are evident across many applications. Phoenix Contact’s Power Reliability portfolio protects the entire power path by using technologically compatible components and joint testing.

It delivers high availability, predictable reliability, and sustainable efficiency in all applications.

Standard-compliant testing as proof of protective effectiveness

Electronic equipment must meet the electrical, thermal, and functional limits defined in its product standards, including specified surge stress levels tested with standardized pulses. Because devices use different circuit topologies and protection concepts, their surge withstand capability varies. In power supply systems, proper coordination between the upstream surge protective device (SPD) and the downstream switched‑mode power supply is essential. SPDs limit surge voltage to defined protection levels, while power supplies include internal limiting, filtering, and rectifier stages. Poor coordination can result in excessive residual voltages, thermal overload, or malfunctions.

Coordination testing verifies whether the SPD and power supply unit interact correctly under transient test pulses. The tests follow the surge waveforms of IEC 61000‑4‑5 and the type‑test parameters of IEC 61643‑11. The evaluation checks whether the power supply can safely handle the SPD‑limited residual voltage and maintain stable output performance. Various power supplies and surge protective devices suitable for the application were tested.

The test team uses a standard‑compliant hybrid pulse coupling network for type 3 devices to test the PLT‑SEC‑T3‑230‑FM‑PT type 3 SPD together with the Quint4‑PS/1AC/24DC/20 power supply. The generator applies 1.2/50 µs voltage pulses and 8/20 µs current pulses at 90° and 270° of the mains phase to capture critical operating states of the rectifiers and EMC structures.

During testing, technicians measure the pulse current, the Quint Power input current, and the PLT‑SEC residual voltage. The hybrid pulse is essential because type 3 SPDs both limit voltage and conduct current, and only this combined surge shape provides a realistic assessment.

Technicians test the coordination between the Trio‑PM/1AC/24DC/2500W power supply and the VAL‑SPP‑T2‑275‑1+1‑UT‑R type 2 SPD according to IEC 61643‑11 using 8/20 µs surge currents. They increase the pulse current up to the nominal 20 kA discharge level to simulate maximum dynamic and thermal stress. During the test, they measure the pulse current and the DC output voltage of the Trio Power supply.

Since type 2 SPDs primarily discharge high‑energy surges, the 8/20 µs waveform is the key test parameter. It verifies that the VAL‑SPP maintains its protection level under full load and that the Trio Power supply continues operating without impairment.

Coordination tests highlight the advantages of coordinated products

The coordination tests show how effectively the SPD protects the power supply and how the supply behaves under surge conditions. They confirm that the upstream SPD significantly reduces the surge current reaching the AC input. In the PLT‑SEC and Quint Power example, placing the SPD upstream cuts the surge current roughly in half, reducing stress on internal components and extending the power supply’s service life.

Compared to standard market products, Phoenix Contact components demonstrate superior coordination. Even when technical data and approvals appear similar, non‑harmonized combinations typically offer lower protection and shorter life expectancy.

A key evaluation factor is the effect of the surge on the output voltage. In the tests with the VAL‑SPP type 2 SPD and the Trio‑PM power supply (Figure 5), the applied 8/20 µs, 20 kA surge current causes a brief disturbance in the 24 V DC output. The voltage briefly rises, then dips, and returns to a stable 24 V DC within about 2 ms. In non‑coordinated combinations, a deeper or complete voltage drop and a longer recovery time would be expected. The overshoot and undershoot are especially important, as excessive amplitudes can damage the connected load.

Significantly higher system availability and longer product service life

The test results show that well‑coordinated product combinations provide clear benefits for the operator. A suitable SPD significantly improves application protection and system availability, and in this example even doubles the service life of the power supply. The choice of SPD depends on factors such as installation location, voltage level, and required protection level, so different applications call for different combinations. PLT‑SEC surge protection paired with a Quint Power supply is ideal for applications requiring very high functionality, such as data centers and critical infrastructure, where maximum availability is essential.

Phoenix Contact optimizes the combination of the VAL‑SPP SPD and the Trio‑PM power supply for machine building. Trio Power units supply DC motors in high‑power systems, and a type 2 SPD protects the power supply when switching inductive loads or decelerating machines. These actions generate higher pulses that can stress the power supply. With this coordinated setup, DC motors continue to receive uninterrupted power even when surge voltages occur in the grid.

The described product combinations also enhance protection and deliver added value in applications. Such as the process industry, battery storage systems, wind turbines, and building automation. In these systems, the design of the power supply and protection components is crucial for overall reliability. With its coordinated portfolio of protection, supply, and monitoring products, Phoenix Contact covers all key aspects of Power Reliability.

Learn more about Power Reliability.