How to Choose Rectifier Water Cooling Or Air Cooling?

Jun 14, 2018
How to Choose Rectifier Water Cooling Or Air Cooling?

Typically there are three methods of cooling methods of rectifiers, air cooling, water cooling and oil cooling. Here we introduce the advantages and disadvantages of water cooling and air cooling:


For high power DC power supply, the environment condition is not good such as with corrosive fumes, much dust, very high environment temperature, requires high IP rating, water cooling is more suitable. 

Like some special environments and sub-tropical climate areas, such as electroplating, anodizing, electrolysis etc. environment, we generally recommend water cooling rectifier.

1) Water cooling Rectifier:

The heat generated by the power semiconductor components inside rectifier will be dissipated through circulated cooling water, cold water(lower than 35℃) goes into the rectifier cooling loop and get hoter water out, through this circulation, the heat is dissipated to keep the rectifier running normally. 

Advantages of water cooling:water-cooling-thyristor-rectifier

A. Less maintenance needed, no need to change cooling fans like air cooling;

B. Rectifier with lower cost;

C. Better cooling performance under high ambient temperature, up to 50℃;

D. Better cooling effect for high power rectifier;

E. Cabinet sealed, suitable for corrosive environment;

F. Higher IP rating;

G. Low noise from rectiifer;

H. Smaller size.


Need user to provide suitable cooling water or we could provide water chiller together on request.

Cooling water quality requirement: 

Better to provide purified deioned water for the rectifier, especially for high voltage rectifiers. 

If could not provide deioned water, the water quality must meet below requirement:




Water quality

PH: 68

Resistivity ≥20KΩcm

Hardness<8 dH


Suspended solid≤30mg/L

Water is not corrosive, dirty

Does not contain acids or salt

Inlet Water Temperature


To prevent condensation, the water must not be too cold. The ideal temperature is between ambient temperature and 35(not below dew point)

Inlet Water Pressure


Water flow

According to rectifier power, the inlet water and outlet water temperature difference is 5℃-10℃.

Connection of Cooling Water: 

Use adaptive cooling water pipe and connectors to connect to the inlet and outlet interface on the rectifier. Below pictures are for example:



2) Forced air cooling Rectifier:


A. Convenient use, needn't extra work on the cooling system;

B. Suitable for low power rectifier


A. In most conditions, price is higher than water cooling.

B. Cooling performance is not as good as water cooling under very high ambient temperature above 40℃.

C. Higher noise from the rectifier. 

D. The IP rating is lower, because of heat exhange between rectiifer inside and outside, the corrosive fumes and dusts may enter the rectifier and will shorten the 

lifespan of the fans and other parts. 

E. Need more maintenance work for the dust clearance.

F. Because the cooling fans are mechanical parts, after some years, they need to be replaced.  

G. Bigger size than water cooling rectifier. 

If users prefer to air cooing for corrosive applications, we recommend rectifiers put in a separate area or room isolated from the plating cells to avoid corrosion and dust. Like the picture:

Air cooling IGBT rectifier installation

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