Technical Assistance with Using Three Phase Power Supplies

7 October 2021

We recently assisted a customer, who was designing a retrofit control system for water pumps used on commercial prawn and Barramundi farms.

These pumps were wired 3 phase Delta (i.e. no neutral).  

Having not done much in the way of 3 phase design, the customer was looking for guidance on using MEAN WELL three phase power supplies.  

The customer could see from the data sheets that many of MEAN WELL’s products offer great isolation resistance and withstand voltage specifications.  

However, the customer had questions around load balancing options and commoning of negatives for DC ground of the control equipment.  

Being Delta wiring, the customer wanted to confirm his assumption that two of the three wires be used for one power supply (5V), with ground wires taken through and strapped to negative rather than floating.  

For load sharing the customer wanted to know if he could put a second power supply (12V or 24V) across a different phase pair. Under the condition of separate phases connecting 2 power supplies, could he still strap both negatives as common together?  

To maintain balance on the 3-phase supply we suggested the customer use the MEAN WELL TDR-240-24 24V power supply.  



This is a fully isolated supply, so earthing the negative side poses no problem. 

For the 5V power supply, we suggested the MEAN WELL DDR-60L-5 DC to DC converter.


MEAN WELL DDR-60L-5 DC to DC Converter


Supplied from the TDR-240-24, the DDR-60L-5 will provide up to 12A and is also fully isolated. 

The customer may need to earth the negative side of the power supply for operation across the full system. 

If you require assistance in selecting a suitable power supply for your application, please do not hesitate to contact Power Supplies Australia