Introduction: At 50°C ambient and at 5,000 m altitude, a 24 V supply's usable output, mounting space and grounding plan all change, so settle the panel layout before fixing the part number.
A control panel for a site 4,500 m above sea level often starts with a simple load count: PLC, sensors, relays, a small HMI and signal lamps. The numbers point to a 100 W, 24 V supply, and the Schneider ABL2REM24045K fits at 24 V 4.5 A in a 129 × 97 × 30 mm open frame. Then site data arrives: summer air inside the cabinet reaches 55°C to 60°C, and the panel must operate year-round at altitude. Full load applies only from -30°C to 50°C, and the 5,000 m rating carries installation conditions. The design task is to translate those numbers into usable output, spacing and a buildable grounding arrangement.
The ABL2REM24045K is rated 24 V, 4.5 A and 100 W, and that full rating holds from -30°C to 50°C ambient. From 50°C to 70°C, the supply must be derated. Treat 50°C as a planning limit. A load acceptable at full rating in a 48°C room may fail in a hot plant room or sun-heated steel enclosure. The 70°C limit is the top of the reduced-load operating range. Derating follows the heat balance inside the supply: switching devices, the transformer and output capacitors generate heat that leaves through the metal frame and triangular vent field. Hotter surrounding air shrinks the temperature difference between components and air, so the same watts are harder to shed. Lowering output current reduces internal losses. Total the real 24 V current with margin and check the allowed load at the hottest air it will see. At 60°C panel air, usable current is below 4.5 A; near 70°C, margin becomes thin and a larger model or better ventilation is the safer answer. Measure ambient where the supply sits, not at the cabinet door: 20 mm below the unit or at the air inlet. A panel with transformers or drives can run 10°C to 15°C above room temperature. If a project needs 3.5 A at 24 V and the site reaches 58°C inside the panel, obtain the derating figure at 58°C before the bill of materials is frozen.
The supply is rated for use up to 5,000 m above sea level, and the installation must compensate for thinner air. Two separate effects meet in the same panel. At altitude the air still moves through the triangular holes, but each cubic metre carries less mass, so it removes less heat per degree. Thinner air also breaks down at a lower voltage, which changes the distance needed between live metal and grounded metal.
At 5,000 m, air density is roughly 60% of its sea-level value. The fanless design depends on buoyancy: air warms, rises through the triangular perforations, and pulls cooler air in behind it. With 40% less mass in each cubic metre, the same chimney effect carries away less heat, so case temperatures rise for the same load. Combine that with 60°C panel air and the unit works against both a smaller temperature difference and weaker airflow. Keep vent faces clear above and below the 129 × 97 × 30 mm body. Do not lay wire ducts across the perforated faces or stand the supply in the rising heat plume from a transformer or drive. Vertical orientation, terminals at the bottom and a clear channel to the top of the enclosure support natural convection better than a crowded layout. On sealed outdoor cabinets at altitude, add a heat exchanger or a filtered fan package sized for the actual internal heat load, and confirm internal air temperature with a test run before shipment.
Thinner air also lowers dielectric strength, which is why IEC 60664-1 applies altitude correction to clearance and creepage distances in low-voltage equipment. The correction factor rises with elevation, so distances that satisfy a sea-level panel may be too tight at 4,000 m or 5,000 m. Keep the mains input side separated from the 24 V output and signal wiring, route the PE conductor on its own path, and avoid letting field wiring cross over the open frame where a loose strand or dropped screw could bridge a gap. Open-type construction means terminals and internal connections are reachable, so the panel must provide the missing distance and physical barrier. Use separate wire ducts for AC and DC, add insulating barriers or a terminal shroud where a metal mounting plate sits close to live parts, and keep the supply off the enclosure wall so debris cannot collect across terminals. Above 2,000 m, note the actual site elevation on the drawing set and check clearance figures against it.
The ABL2REM24045K is Class I equipment, so a protective earth connection is part of the circuit. Bond the metal chassis to the panel's protective earth with a dedicated conductor and proper terminal, not through the mounting screws alone. IEC 60204-1 treats protective earthing as a basic safety measure, and the bonding path must remain low-impedance over vibration and thermal cycling. Use a clearly marked PE stud, a correctly sized green-and-yellow conductor, correct terminal torque, and a continuity measurement at each bonding point before panel sign-off. At altitude, with tighter clearances and the same fault energy, a solid PE path is the main defense against a live enclosure. Whether 0 V is bonded to protective earth, and where that bond happens, affects noise, ground loops and sensor behavior. Pick one arrangement, document it, and keep it consistent across the machine line. IP20 defines what the supply itself defends against: it keeps fingers and larger solid objects out of the frame and offers no water protection. The supply is an indoor component for a closed panel; enclosure, gaskets, cable glands and door seals provide the real environmental protection. Keep it away from washdown spray, hose mist or roof condensation, and in cold sites add an anti-condensation heater so moisture does not form on the terminals during temperature swings. The fanless design removes the fan filter from the maintenance list, but the panel still needs its own thermal plan. Bring the key decisions together in a short design review before requesting pricing: measured panel ambient, site altitude, the 24 V load list with margin, and the grounding and spacing layout. Send load figures, elevation and cabinet temperature profile through Get A Quote to confirm derating for the ABL2REM24045K; route the request through Kayolo Outdoor Furniture and include ambient, altitude, load list and grounding layout.
A 24 V supply for 50°C and 5,000 m combines two designs. The electrical side sets usable current: full load to 50°C, then a reducing load as the panel climbs toward 70°C. The mechanical side sets how well the fanless frame sheds heat in thin air and how much distance the installation must add to keep mains and output apart. Wrap those around Class I protective earthing and a realistic view of what IP20 leaves to the enclosure, and the panel can meet the conditions the drawings assume. Confirm the derating figure at your measured panel temperature, the clearance approach for your elevation, and the PE terminal arrangement when you request a quotation.
A: The supply delivers its full 24 V 4.5 A rating from -30°C to 50°C. Above 50°C it must be derated, so the allowed output current falls as ambient rises toward the 70°C upper limit of the operating range. Plan on less than 4.5 A at 60°C panel air, and confirm the derating figure for your measured temperature before fixing the load list.
A: The model is rated for use up to 5,000 m, but the full 24 V 4.5 A rating applies only within the -30°C to 50°C ambient band. At 5,000 m, thinner air reduces natural-convection cooling, so keep panel air temperature as low as practical with clear vent faces. Where heat and altitude combine, size the load below the rated 4.5 A and confirm derating for the actual site.
A: Bond the metal chassis to the panel protective earth with a dedicated green-and-yellow conductor and a proper PE terminal, not through the mounting screws. Keep the run short and low-impedance, torque the terminal to specification, and measure continuity at each bonding point during panel sign-off. At altitude, with reduced clearance margins, that solid earth path is the primary protection, so show it on the panel drawing.
IEC 60529:1989+AMD1:1999+AMD2:2013 CSV
