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EMA Inc.

Changes in the Siemens MV VFD Brand Family

Our Founder, Eddie Mayfield, with EMA’s first Perfect Harmony Load Stand

Over the past 10 years, EMA has been heavily involved with  repairing and servicing Medium Voltage VFDs. The most common drive we service,  both in the field and in our repair shop,  is the Siemens Perfect Harmony MV VFD. The Siemens/Robicon Perfect Harmony Drive was the first successful voltage-source medium voltage VFD in the industry. The H-Bridge design uses low voltage, single-phase output power modules cascaded together to generate medium voltage using low voltage power components. This simple and inexpensive design allowed Robicon (later purchased by Siemens) to gain significant market share in the medium voltage VFD market. However, there has been a recent change in the Siemens MV VFD brand family: the perfect harmony series drive has been updated to the Sinamics GH180.

EMA has invested heavily in developing in-house load stands for Perfect Harmony Medium Voltage VFDs as well as portable power cell testers for power cells from those drives. The portable power cell tester enables us to repair single power cells and test them before installing them into the Perfect Harmony MV VFDs. These load stands and testers can accommodate the changes in the Siemens MV VFD brand family; EMA can repair the Sinamics GH180 as well.

Siemens maintained the Perfect Harmony brand name from the original Robicon design for many years, and has just recently moved to the Sinamics GH180 brand name. The Sinamics GH180 design uses the same cascaded H-bridge topology that made the Perfect Harmony line so successful. The older generations of the Perfect Harmony up to GEN4 use electrolytic capacitors which have a life span of seven years; See our blog on electrolytic capacitor life for more information. Some of the newer Sinamics GH180 use film-type capacitors which have a 15-year life span. This is a great improvement in the cost of ownership for the end user given that the useful life of the bus capacitor doubles when going from electrolytic to film-type capacitors.

EMA Service Engineer Franklin Flores removing a power cell from a Siemens Medium Voltage VFD

EMA performs complete refurbishments on Perfect Harmony MV VFDs. This includes replacing all bus capacitors as well as electrolytic capacitors on cell control boards. Whether you need field service or cell repair, EMA is here for you. Just because there have been changes in the Siemens MV VFD brand family, doesn’t mean you can’t expect the same great service from EMA. No One ANYWHERE, Is Better At Drives Than We Are. Click the chat to the right, call us at our number above, or email us at info@emainc.net to discuss your Siemens medium voltage VFD needs today!

Written by Abdou Barrow: General Manager, EMA

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