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Refurbishing and modifying Medium Voltage VFDs

EMA is in the process of refurbishing and modifying a set of medium voltage VFDs, changing them from a 3300 VAC input to a 4160 VAC input.

We recently acquired a set of 1000 HP Toshiba T300MVi medium voltage VFDs. These units were originally designed for a 3300 volt input. In order to make them useable for the more common 4160 volt applications, it was necessary to remove and retrofit the input phase shifting transformer.

This is not a minor task; the input transformer for these medium voltage VFDs weighs about 4000 lbs, and it’s not a simple 3 phase transformer.

The Toshiba T300MVi medium voltage VFD uses a phase shifting input transformer, which has the advantage of mitigating the negative harmonics that would otherwise be reflected to the input line. (See this blog on harmonics) (See this on Harmonic Filters) . This also allows 5 Step PWM and bus clamping topology that the Toshiba T300MVI medium voltage VFD uses to allow easy application to existing motors, and keeping the common mode voltage low.

Great care has to be taken when retrofitting the input transformer in a medium medium voltage phase shifting transformervoltage drive, not only because the medium voltage connections are critical, but because of the size and weight of the transformer, and the necessity of maneuvering it within a tightly confined space.

Once this is done, then the rest of the refurbishing is more familiar electrical and electronic modification and tuning in order to produce a 1000 HP medium voltage VFD. These units carry a complete one year warranty, and are fully functional. The beauty is that these 1000 HP medium voltage VFDs are ready for immediate delivery. As of this writing, deliveries for standard medium voltage VFDs are running 5 to 6 months.

Do you need a 1000 HP or less, 4160 volt, medium voltage VFD? If so, then hit one of the contact icons on the left of this page, and we’ll get the information to you. (these drives can be used from 300 to 1000 HP applications)

Remember, that EMA can do installation, startup, and service on these units.

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