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In the industrial automation industry, static phase converters can have somewhat of a love-hate relationship with engineers. Why? You may ask.

Well, static phase converters are typically designed to have a running load capability around only 66% of the rated power under normal run conditions. In certain pieces of equipment, this causes no conflict but for other machines, it may be problematic. You may hear many different stories out there of the success and failures of static phase converters being used in applications depending on the brand/specs of both parts.

Here’s a cool story that we had recently regarding an American Rotary Static Phase Converter.

“I bought the DSS-1-5D when my old phase converter died. After I connected it, I found the performance on my Bridgeport was similar to the old converter, but the performance on my 3hp lathe was very noticeably and pleasingly better. It actually got here a day ahead of the scheduled delivery.”

This is a great example of how operating results can vary greatly between the types of machines when applying a static phase converter. 

Now, let’s get to the meat of the matter…we’re talking about applications, installation and sharing the information our technical support team receives directly from the manufacturer. 

Starting with the basics, how do you find the right static phase converter for your application?

Properly size your phase converter and wire

  1. The HP (horsepower) of the first motor to start must be between the HP ratings of the phase converter.
  2. Motors smaller than the 1st motor may be started after the 1st motor is started.
  3. The smaller secondary motors may be kept running even when the first motor is stopped and/or restarted.
  4. Trying to start a motor smaller than what the converter is rated for can over-excite the motor and cause damage to the converter and/or motor.
  5. Note: A larger static phase converter will NOT provide more power.
  6. Wires should be sized for the maximum rated peak current of the motor or machine, whichever is greater.
  7. Hint: It helps the motor functionality to incrementally go up in AWG wire size for every 50’ of run
  8. Special note: All local codes should be used to ensure proper wire size and it is recommended that installation be performed by licensed electrician.
  • Any equipment with controls or magnetic switch gear MUST operate the controls from the single phase lines T1 & T2. The direction of the motor can be reversed by switching the two single phase lines.
  • On the DSSD Unit, a red indicator lamp is illuminated when the start circuit is applied. The lamp should only stay on for a maximum of 3 seconds. The “micro-smart” controller will disengage the start circuit to prevent damage and the converter will NOT disengage the single phase line.  Always wait until the lamp is off before walking and if your machine or motor has not started in 3 seconds then turn the machine off immediately and troubleshoot the installation.
  • If you have a geared machine, always start the machine out of gear or put it into the lowest possible gear in order to reduce the starting load. If the machine does not start within 2-3 seconds, turn it off and troubleshoot the installation.
  • In this type of installation, DO NOT use fuses between the phase converter and the motor. They may only be used on the single phase side. A three phase breaker or magnetic motor starter may be used between the phase converter and the motor so that all three lines break at the same time.
  • If the application is a heavy load (I.E.: compressors, pumps, blowers, etc.), one should reduce gearing by 30% or increase the motor size by 50%
  • If the unit is a DSS-D static converter, then the toggle must be set to the proper range based on load.
Check out these extra handy tips for selecting a phase converter from our vendor, American Rotary!

So what’s the moral of the story? Even if the item has the same horsepower, different types of machines or loads may produce very different performance outcomes. When purchasing a new phase converter, static or otherwise, it’s best to start with as much information as possible. 

Need technical support to help you find the right converter? They’re happy to help! Feel free to email our tech team directly at: or give us a call at: (847) 658-8130 and we’ll help you find the right converter for your application.

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