You will see in many of our instruction manuals a warning about not connecting power supplies in parallel that do not have current share capabilities.
At first it would seem a nice easy way to get extra
current. Take two like power supplies,
connect them together and they will deliver twice the current?
Unfortunately there is a good chance that the two power
supplies will not current share due to their output voltage set points. The power supply with the highest output voltage
setting will deliver as much current as it can until it reaches its current
limit threshold and then the output voltage starts to drop. The second power supply will then take over
and provide the balance. The output
voltage might glitch during the transition, affecting system operation.
For example, take two 24V 10A power supplies with an over
current set point of 120% powering a 15A load:
Power supply A might
deliver 12A (now at its current limit point)
Power supply B would
then deliver 3A.
One could argue that the power supply is being protected by
the current limit. There are two issues
with this though:
1. A
power supply is not designed to operate in current limit indefinitely. Internal
temperatures will rise, reducing the life of the product
2. The
safety certifications for UL, CSA are based on 100% load, not 120%
My recommendation is to use a power supply with a higher
current rating, or choose one with a current share feature.
