Technical Service Center/Willard Wu
willard@meanwell.com

3?4W (Three-phase four-wire) UPS systems are widely used in large commercial facilities, industrial plants, data centers, medical institutions, transportation, and other fields that require stable power, extending to mobile power applications. In these environments, many devices are highly sensitive to power outages, including servers, manufacturing machines, medical instruments, and communications equipment. The 3?4W UPS system provides stable three-phase power and balances the load between each phase to ensure voltage stability, preventing equipment damage due to power fluctuations or interruptions.

For mobile applications, such as outdoor activities, emergency vehicles, or temporary construction sites, mobile three-phase UPS systems are especially important because they provide reliable power protection in the absence of stable mains power. This capability ensures that critical equipment can operate reliably in any location, maintaining business continuity and operational efficiency, and preventing data loss or production interruptions due to power outages.

MEAN WELL's newly launched NTN-5K is a highly reliable 5000W off-grid sine wave DC-AC inverter featuring a built-in AC charger and UPS function (AC bypass). With battery support, it is suitable for households, offices, vehicles, boats, remote mountain areas, and outdoor off-grid applications. In addition to single-phase usage, three NTN-5K units can be combined to provide a three-phase, four-wire (3?4W) AC output. This setup can be applied to three-phase four-wire (L1/L2/L3/N) equipment or used to connect phase voltages (L1/L2/L3-N) separately to single-phase equipment.

The differences for each phase are configured using the SW1 dip switch, as described in the table below:  
 

 

S1	S2	AC Output Phase
OFF	OFF	L1, 00
OFF	ON	L2, -1200
ON	OFF	L3, +1200

Additionally, for applications using 110VAC/220VAC single-phase three-wire systems, you can also use the following wiring method and dip switch settings. However, please be aware that if you are connecting AC power sources, these two AC power sources must be independent. Otherwise, a short circuit may occur through the internal circuitry.  
 

For related product and application requirements, please contact MEAN WELL distributors or MEAN WELL application engineers.
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