Tech Articles

We buy surplus medium voltage VFDs from cancelled projects

EMA buys surplus (used and new) medium voltage VFDs from cancelled projects and equipment upgrades. If you have surplus medium voltage VFDs in your inventory, you should contact us by any of the methods on this site, or by calling 770-448-4644. In general, EMA is interested in the used or surplus medium voltage variable frequency drive (VFD) regardless of condition. Again, just call 770-448-4644 or use any of the contact methods on this page, including the live support feature. We sell,…

Power Quality Issues Residue of Electronic Motor Drives

The application of electronic variable speed drives to electric motors has grown dramatically. Since transistorized inverters (AC Drives) became readily available in the early 80’s, the expansion of this technology has been remarkable. No longer an esoteric discipline, reserved for a few specialists, Drives have become commonplace. The expansion of usage hasn’t been without problems; earlier AC Drives were notoriously unreliable, expensive, and difficult to tune. There was additionally, little understanding of their function and theory outside of select groups.…

Field Service Engineer / Technician Norcross, GA

EMA has an opening in our Norcross, GA Facility for a field service engineer technician. EMA is a leader in the Variable Speed Drive (Variable Frequency Drive) service business and we need a sharp individual to join our great team. An EMA Field Service Engineer Technician will service, install, and repair variable frequency drives. This is a wonderful career opportunity for an experienced field service engineer, or a beginner wishing to learn. The ideal candidate will have experience with medium…

Eaton SC9000 Series MV VFD Repair and Overview

EMA repairs and provides preventive and predictive maintenance on the Eaton SC9000 MV VFD. We have a fully functional test stand for these units. We repair most Medium Voltage VFDs including the Eaton SC9000, the Siemens Robicon Perfect Harmony, the Toshiba T300MVi , Ansaldo / Ross Hill, ABB, Yaskawa, and others. Here’s a short overview of the Eaton SC9000: The Eaton SC9000 series MV VFD is a 24 pulse three level topology VFD with integrated phase shifting transformer. In today’s…

Refurbished Medium Voltage VFDs for sale

EMA has refurbished medium voltage VFDs in stock and for sale. They carry a full warranty and are fully tested and operational. Most are rated at 4160 volts. As far as we know, we have the largest stock of refurbished medium voltage VFDs in the world. There are several reasons to consider a refurbished medium voltage VFD. Cost.. Significant cost savings are accomplished by using refurbished medium voltage VFDs. Delivery.. Most of the refurbished medium voltage VFDs we have in…

EMA: 29 years of Medium and Low Voltage Service

EMA is thankful to be celebrating 29 years of Medium and Low Voltage Drive service. We have the best customers in the world, located all over the globe. EMA recently performed medium voltage VFD service in Qatar, France, Canada, Columbia, and Mexico. In addition we’ve been doing medium voltage VFD service on off shore oil platforms in both the Gulf of Mexico and California, and a number of industrial plants and municipal water and waste water plants all over the…

The Modern Day Linebackers of Medium Voltage Drive Service

While preparing for the upcoming NFL draft, I am struck by how often we hear the draft pundits refer to the “modern day linebacker”: a player who’d be considered undersized by traditionalists but whose speed and agility allow him to cover a wide area and be utilized in a variety of ways. As offensive schemes and rules evolve to promote offense in 5-wide, empty backfield configurations, the defenders, particularly linebackers, are forced to be hybrid-type players. 2018 draft picks Roquan…

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…

Siemens Robicon Perfect Harmony VFDs on LNG Ships

We recently had the opportunity to service Siemens Robicon Perfect Harmony VFDs on a LNG Carrier (Ship) in the middle east. When natural gas is cooled to minus 259 degrees, it assumes a liquid state. Liquefied Natural Gas (LNG) is much more efficient to transport than compressed natural gas (CNG). It is particularly suited for large LNG Transport Ships. The problem is keeping it cool. Many LNG Ships use large compressors to lower nitrogen to around minus 321 degrees where…

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…

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