EMA Inc.

York MVVSD Repair

  York MVVSD (Medium Voltage Variable Speed Drives) series drives are used on large, medium voltage York chillers, in ranges up to 10,000 horsepower. It is common to see VFDs used in low voltage chillers and compressors, but due to decreasing costs of electronics, medium voltage VFDs are becoming more common because of the potential energy and mechanical savings on medium voltage chillers and compressors. For further information on how VFDs can save energy on variable torque applications, click here.

VFDs for Soft-Starting: Not Glamorous, but Necessary

Variable Frequency Drives (VFDs) can be used in a variety of applications for a variety of purposes. As a service engineer, I’ve seen some interesting applications using VFDs: tunnel boring machines, carnival rides, mechanical bulls, and electric cranes are just a few that come to mind. On a list of interesting tasks assigned to VFDs, using one for soft-starting is at the bottom, yet it is very common and often necessary. Because a VFD varies the voltage as well as

Eaton MCC

Square D and Eaton MCC medium voltage Softstarters

We work on quite a few Square D and Eaton MCC Softstarters.   Most of them, as it turns out, are actually manufactured by Motortronics. Motortronics has a done a great job at capturing the medium voltage softstarter market.  Square D, Eaton, and other MCC manufacturers simply brand label the Motortronics softstarter and install. This isn’t to denigrate either Square D or Eaton MCC medium voltage softstarters.  Brand labeling is a common and efficient practice by a number of MCC medium

Pre Charge on Siemens Robicon Perfect Harmony VFD

One of the key features of all low voltage VFDs is their ability to softly charge the DC bus capacitors. This feature is not a readily available on the Siemens/Robicon Perfect Harmony MV VFDs. The Perfect Harmony VFD can be easily modified to include this feature.  Soft (or Pre) charging the bus capacitors limits the inrush current upon power up, and prevents damage to transformers, power devices, and other connected devices. Within the Siemens Robicon Perfect Harmony medium voltage VFD

Medium Voltage Power Cell

Field Site Testing Siemens/Robicon Perfect Harmony Cells

Siemens/Robicon Perfect Harmony Power Cells (power modules) can be tested in the field, at the job site. Field testing the Perfect Harmony Power Cells (power modules) takes special equipment, which we developed, exclusively for testing the Siemens / Robicon power cells (power modules).   We also repair and test the power cells at our Norcross, GA facility, using a complete Siemens/Robicon Perfect Harmony drive test stand.    It is not always practical to ship Siemens/Robicon power cells (power modules) to

Low Cost Medium Voltage VFDs

Medium Voltage VFDs are coming down in price as the market grows more competitive.  Nonetheless, they remain expensive. The cost is not only the initial price, but the size of medium voltage VFDs means the installation costs are significant.   All that said,  at EMA we love medium voltage VFDs, enjoy repairing them, and selling them.  They are very reliable, and are becoming more and more commonplace.  One way to greatly reduce the purchase price and get low cost medium

Industrial Internet of Things

The Industrial Internet of Things IIoT and VFDs.

Industrial Internet of Things IIoT and VFDs.  Our primary business is variable frequency drives (VFD) and our focus is high horsepower and medium voltage VFDs.  We’ve seen incredible technical innovation in the last decade and often wonder what the future holds.    Vector drive technology, made possible by very smart people using smarter and smarter microprocessors, and advances in power semiconductors,  had a huge impact on the market.   So what’s next? Almost everyone expects smarter equipment, and that  always

EMA Inc.

Water Treatment: Making America Great

(Eddie Mayfield is the President of EMA, a company specializing in Electronic Motor Controls with particular expertise in Water and Water Treatment facilities) I had the opportunity to visit St. Petersburg and Moscow a few years ago.  Both are beautiful cities, much nicer than I anticipated.  St Petersburg, with its beautiful art and history is striking.  I was amazed at how picturesque Red Square in Moscow was.  Both cities were great to visit, the people were wonderful, and I hope

Rockwell Allen Bradley Powerflex 7000 Shorting Issue

We recently had a customer sustain significant damage on their 2500 HP Allen Bradley Powerflex 7000 medium voltage VFD due to degraded rubber O-rings designed for reducing noise between the SGCT and the heat sink it sits on. After some digging, we found this to be a known problem in this Rockwell medium voltage VFD. In November of 2016 an engineering note was released in the Rockwell Knowledge base regarding the Powerflex 7000 medium voltage VFD: note 969771 states: “In

Medium Voltage VFD Field Service

Field Service on Medium Voltage VFDs

Our primary business has become field service on medium voltage VFDs. If you need Field Service on a medium voltage VFD..