Delta’s PJ Series is built for compact spaces, peak loads, and harsh environments

Industrial and commercial equipment rarely hands the power supply an easy specification. For example, a test bench instrument may need to fit a shallow enclosure yet survive the inrush of an actuator under test; an elevator controller must ride through brief sags on the building feed without faulting, and a refrigerated display case must run efficiently and reliably in environments full of dust and condensation. Specifying a separately optimized supply for each of these jobs can needlessly multiply your qualification work and, ultimately, your inventory.

Delta Electronics designed its second-generation PJ open-frame series (Figure 1) to meet this mix of demands in one family, with 100 W and 150 W models offering 12 V, 24 V, and 48 V outputs, a universal AC input of 85 V_AC to 264 V_AC, and a wide DC input range of 120 V_DC to 373 V_DC. They are offered in both open-frame and enclosed configurations, allowing the same electrical design to serve various installation requirements.

Figure 1: The PJ 2nd-generation industrial open-frame power supplies. (Image source: Delta Electronics)

A single part balances durability and efficiency

The concept behind Delta’s PJ Series is combining industrial-grade durability with commercial-grade efficiency into one design, suitable for use in either sector. Power supplies are usually chosen for cost, compactness, and often force trade-offs. For example, a unit robust enough for a factory floor tends to be over-built and power-hungry, while a unit tuned for efficiency in a commercial fixture tends to be fragile in the field. By combining peak-handling, ride-through power, environmental robustness, and an efficient front-end into a single family, the PJ supplies serve as strategic building blocks across several product lines, offering savings in qualification, sourcing, and inventory. Standardizing on one family also shortens design cycles, because a board team can reuse the same footprint, hold-up behavior, and protection scheme from one product to the next rather than re-characterizing a new supply each time.

The flexibility of the PJ series also extends to their wide input voltage range. A single part can run from ordinary mains, a rectified or DC-bus distribution scheme, or from a backup source, avoiding the need to specify a different supply for each power architecture. This DC capability is useful where equipment draws from a battery string or an intermediate DC bus, as the same unit that runs on AC during normal operation can keep running on stored DC energy during an outage, without having to qualify a second power stage.

Solving the space vs. peak-power problem

Motors, solenoids, and the mechanisms inside automated test equipment draw far more current at startup than they do in a steady state, sometimes several times their nominal load. To sustain these inrush surges, the PJ series provides a 200% power boost for up to ten seconds, which is usually enough time to let a motor come up to speed or charge a bank of input capacitors before the load settles back to its continuous draw. The PJ supplies maintain a 27 mm low-profile open-frame footprint that drops into space-constrained installations. A built-in remote ON/OFF function makes it easy to sequence and control from a larger system, which is useful when several rails must come up in a defined order or when a controller needs to reduce load and cut standby power.

Safety, compliance, and clean power-up

The PJ series is certified to the IEC/EN/UL 62368-1 safety standard and is fully compliant with Japan's PSE regulation, which confirms its safety pedigree and streamlines entry into Japanese markets, a key advantage when a product has to ship into multiple regions. IEC 62368-1 is the hazard-based standard that has replaced the older 60950-1 for ICT and audio/video equipment, so designing around it positions a product for current approvals rather than a legacy baseline. Additionally, the series low inrush and low leakage current can help minimize the strain on upstream protection when several supplies share a feed. For installers, this means breakers and fuses are less likely to nuisance-trip when a bank of equipment powers up.

Efficiency and protection in commercial and industrial spaces

Another consideration is the link between efficiency and running cost. Commercial fixtures like display cases run continuously, so every percentage point of lost efficiency directly increases operating costs and may also appear as extra waste heat that must be removed. Factory-floor placement can also expose boards to airborne dust, moisture, and chemicals that can degrade unprotected electronics over time.

Delta’s PJ supplies address the energy side with active power factor correction and a high-efficiency design that complies with the IEC/EN 61000-3-2 Class A limits for harmonic current emissions, keeping their distortion of the AC line within specified limits while lowering operating costs.

For higher durability, the PJ supplies use conformal-coated printed circuit board assemblies that form a barrier against dust, moisture, and chemical contaminants. The coating matters most on fine-pitch boards, where condensation and ionic contamination can create leakage paths, corrosion, or dendrite growth between closely spaced conductors.

Delta’s PJ supplies operate across an ambient temperature range of -40°C to +70°C. At the top end, they deliver full output up to roughly +50°C, then derate gradually toward their +70°C limit. The low end is handled by a -40°C cold-start capability, removing the uncertainty of startup for equipment that sits unpowered in cold or unconditioned spaces, such as outdoor enclosures or refrigerated fixtures.

Conclusion

All in all, the PJ series’ value is in consolidation. Rather than specifying separate supplies to handle peak loads, ride-through, efficiency, and environmental protection, the PJ supplies let you address all of them with one open-frame family, configured to the installation requirements.

For more information on the PJ supplies, please visit Delta’s PJ 2nd Generation open-frame power supply product highlight.