0.5R 72W (max) Resistive Load

[Brian C]

I made 10 pcs of 72W 0.5Ohm load module for +5V rail loading test. Each modules can sink 10A ( 50W ). The resistor body temperature hits ~170 oC in just 5 minutes. It sure needs fan cooling ... PCB temperature is about 110 oC.

( 1 ) The Load Module

( 2 ) Resistor Body Temperature

[yanz]

Re: 0.5R 72W (max) Resistive Load

Whaa.. NICE! Sure it needs an active cooling. I built one like that, but not as massive as yours.

[KeriJane]

Re: 0.5R 72W (max) Resistive Load

Hi Brian

I just did something similar with my PSU load tester....
I got 3 x 1Ω 25w wirewound resistors for the 5v rail for 75w total. With two fans for cooling, I keep the resistor temperature under 70℃.

Remember, the resistors de-rate (increase resistance and reduce current) at higher temperatures so airflow or heatsinks are needed to keep a constant load over time.

Those look really nicely made but aren't the resistors awfully close to each other? That could make them difficult to blow cooling air through.

Here's a diagram of how I arranged the resistors for cooling in my PSU tester.

Have Fun,
Keri

[Brian C]

Re: 0.5R 72W (max) Resistive Load

Your wirewound resistors has much lower temperature coefficient than my metal oxide film ...
The metal oxide film has TC of ±350ppm/oC. I will get some data of Resistance vs Temp. when I am free.