Kilowatt-class enclosed AC-DC power supply: a 1–1.7 kW single-output unit with active power-factor correction, rated by its input current, cooling method, peak load and paralleling

01

What 1.5 kW pulls from the mains: up to 19 A at 100 V, power factor 0.95–0.98, and the IEC 61000-3-2 harmonic ceiling

On the input side a kilowatt unit departs furthest from a small module. COSEL's datasheet gives the PBA1500F's line current, power factor and inrush at both mains ranges, and the harmonic table summarised by UNICAMP shows the limits that the power-factor stage has to meet. [1] [4]

In the UNICAMP summary of IEC 61000-3-2, Class A, which covers equipment not placed in the portable-tool, lighting or special-waveshape classes, is limited in absolute amperes: 2.30 A at the 3rd harmonic, 1.14 A at the 5th, 0.77 A at the 7th, 0.40 A at the 9th, 0.33 A at the 11th, 0.21 A at the 13th and 2.25/n A from the 15th to the 39th. Class D (special waveshape, 75–600 W in that summary) uses milliamperes per watt (3.4 mA/W at the 3rd), and the summary sets no limits for systems below 220 V line-to-neutral. The standard applies to equipment drawing 16 A or less per phase; IEC 61000-3-4 extends it above 16 A. [4] The UNICAMP slides follow an earlier edition of the standard, so check the class boundaries against the edition your market requires.

COSEL states that its small PBA models without an active filter (10–30 W) may not meet input harmonic standards when multiple units are used in one system; for the PBA1500F the datasheet lists power factor 0.98/0.95 typ. and compliance with IEC 61000-3-2. [2] [1] RECOM likewise warns that leakage current, EMI, inrush current and harmonics increase when multiple RACM1200-V units are used together. [3]

Editorial calculation: at 200 V the PBA1500F's 10 A typ. input means a Class A 3rd-harmonic limit of 2.30 A is 23 % of the line current. At 100 V the same supply draws 19 A typ., which is above the 16 A per-phase boundary of IEC 61000-3-2 and on a supply voltage the UNICAMP summary sets no limits for; the same summary says equipment rated for a voltage range is tested at 230 V. [4]

Ask the supplier for input current at your lowest line voltage, the measured power factor and harmonic test report (class and edition), inrush at cold start, and leakage current for the equipment class you are building.

02

Internal fan or baseplate: PBA1500F derates from its rating up to 71 °C, RACM1200-V gives 1,000 W fanless and 1,200 W only with 2.5 m/s of air

The two published designs take opposite routes to shed their internal loss (about 50 to 250 W in the calculation below), and the choice changes how the supply is mounted and maintained.

COSEL's PBA1500F is forced-cooled by an internal fan in a 178 × 61 × 268 mm case weighing 3.4 kg max., rated for −20 to +71 °C with derating by ambient temperature (air drawn in for cooling); the ventilation holes are on the mounting side, and the thermal protection may shut the output down if the fan stops or its airflow is blocked. Options include a long-life fan, a low-speed fan and a reverse-exhaust version. [1] [2] Full-load efficiency is 84–87 % typ. at 200 V for the 12–48 V models, falling to 75 % typ. for the 3.3 V model. [1]

COSEL's life-expectancy table for the PBA300F to PBA1500F gives 7 years at 50 % or 100 % load with an annual average ambient of 40 °C or less, and 6 years (50 %) or 5 years (100 %) at 50 °C; the 7-year and 6-year figures assume the fan is maintained, and COSEL says fans should be exchanged on a regular basis. [2]

RECOM's RACM1200-V has no fan: a baseplate carries heat into the equipment chassis. Without external forced airflow, continuous output is limited to 1,000 W at the high input range with ambient below 40 °C and baseplate below 70 °C; with 2.5 m/s of forced air, 1,200 W continuous is available above 172 V input. RECOM states peak efficiency up to 95 %, measured at nominal input and 40–60 % load, an operating range of −40 to +80 °C, and a baseplate limit of 90 °C at 80 °C ambient and 30 % load. [3]

Editorial calculation: at 87 % efficiency a PBA1500F-24 delivering 1,680 W dissipates 1,680 × (1/0.87 − 1) ≈ 251 W inside its case; at RECOM's 95 % peak efficiency, 1,000 W output means about 53 W into the baseplate. The second figure applies only at the 40–60 % load point RECOM quotes.

State whether the supply will see moving air or must be conduction-cooled, the highest air or plate temperature at the mounting point, and whether fan replacement is acceptable as maintenance.

03

Short peaks and paralleling: 105 A for 10 s at 24 V, and up to five units sharing 90 % of their summed current

The PBA1500F-24 is rated 65 A at 100 V input and 70 A at 200 V, with a 105 A peak; the -36 model gives 47 A with a 70 A peak. Peaks are allowed only at AC 170–264 V, for up to 10 s at a duty of 35 % or less. Overcurrent protection works above 105 % of rated current or 101 % of peak current; on the PBA1000F and PBA1500F, overcurrent lasting 5 s shuts the output down and needs the input switched off for more than 3 minutes to restart. [1] [2]

Up to five PBA1500F units can run in parallel with a master-slave harness; COSEL says current differences between units are 10 % at most and the total load must not exceed rated current per unit × number of units × 0.9. N+1 redundancy is also possible, with the output voltage able to change by about 5 % when one unit stops. [2] RECOM's RACM1200-V has active load sharing over a handshake line, a 12 V fan output and a 5 V/1 A standby output, and its boost rating is governed by a 60 s window: nominal power × 0.9 × (recovery time + peak time) must be at least peak power × peak time + recovery power × recovery time. [3]

Editorial calculation: five PBA1500F-24 units at 70 A each give 5 × 70 × 0.9 = 315 A at 24 V, about 7.6 kW of usable output under COSEL's paralleling rule.

Give the supplier the continuous current, the peak current with its duration and repetition, and whether units will run in parallel or N+1.

04

What to send for a kilowatt-class AC-DC supply

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Output: [voltage; continuous current; peak current, duration and duty]
Input: [line voltage range; single or three phase; harmonic class and standard edition]
Cooling: [internal fan, external airflow in m/s, or baseplate to chassis; maximum ambient or plate temperature]
Paralleling: [number of units; current sharing or N+1]
Safety: [IEC 62368-1 or medical; leakage limit]
Signals: [remote on/off; remote sense; power-good; PMBus]

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