At Phoenix Phase Converters, we often receive a lot of technical questions from our customers who inquire about ensuring that they have set their equipment properly. Recently, one of our customers asked:
-
If I need to get down to 208V, should I do that first and then convert to three-phase?
-
Do you recommend an auto-start for this application, since I won’t be running the machine all the time?
-
I want 90-100 usable amps at 208V three-phase. What is the best way to size a converter?
These are amazing questions, and today, we will provide thorough details on each one here.
-
Should You Step Down to 208V Before or After the Phase Converter?
If your application requires 208V three-phase power, the best way to get to the appropriate voltage is to have a step-down transformer after the phase converter.
Here’s why:
-
The step-down transformer after the converter will provide evenly distributed three-phase voltage at 208V, providing your equipment exactly what it needs.
-
In case you put the transformer before the converter, the current draw gets doubled on the single-phase side. That means you would need a single-phase transformer, which is double the size, which increases the additional expense as well as decreases efficiency.
Key Takeaway: Always add the transformer after the phase converter when stepping down to 208V.
-
Should You Use Auto-Start With a Phase Converter?
Many customers have enjoyed the convenience that comes with an auto-start (Auto-link), and of course, it works really well. However, there are some efficiencies to consider.
-
If you turn on your equipment more than 3 times in 24 hours, it is usually more efficient to have the converter running all day.
-
Why? After your third startup (and sometimes sooner), the energy for each of those startup cycles is, at the very least, equal to or exceeds the energy to keep the converter running.
-
By simply leaving it on, you have eliminated the wear and tear from repetitive start-ups.
Key Takeaway: Auto-start may be great if you cycle your system regularly. But when you are starting the equipment so frequently, leaving your converter on is definitely going to be the most efficient option.
-
How to Size a Converter for 90–100 Usable Amps at 208V Three-Phase
When sizing a rotary phase converter, there are a few things to consider other than just running amps. Here are those factors:
-
Running Amps – The continuous load or regular use
-
Full Load Amps – The maximum draw for heavy use
-
Inrush Current – The surge when you start the motor
-
Inductive or Resistive Loads – Motor loads act differently than resistive loads, like heaters.
In this case, if the system requires 90-100 usable amps at 208V, we will size the converter with enough cushion to manage the startup surge and ensure reliable operation.
One advantage of having Phoenix Phase Converters is that they are scalable.
-
You are not locked into a certain size
-
If your needs grow into requiring more capacity later, you can always add another phase converter and pair them together
Final Thoughts
When it comes to powering 208V three-phase equipment, the best solution is to use a phase converter with a transformer after a converter. And, if you add an auto-start feature, you won’t even have to be there to power up your equipment. Keep in mind to size the phase converter for running amps, inrush amps, and full load amps with an extra margin for safety.
At Phoenix Phase Converters, we consult with customers to help design the ideal solution to their application, whether that be CNC machines, pumps, compressors, or any equipment used in an industrial shop.
In case you have any questions or concerns about sizing and setting up your phase converter or transformer, please reach out to us today, and we will guide you to the best possible solution for your shop.