With the advancements in technology, VFD manufacturers have made low voltage VFD’s user friendly and interface-easy to a point that most electrically inclined customers can start up their own low voltage VFDs. This is not the case on Medium Voltage VFDs. The potential for damage to the equipment and personnel could be huge when it comes to Medium Voltage VFDs. This equipment is sophisticated enough to require a professional start up.
I was recently involved in starting a Toshiba T300MVi medium voltage VFD, on a chilly day in the west Texas oilfields, where the 2000 horsepower, 4160 volt drive was being used as a soft start on a compressor. At this remote oilfield location, the utility power was just not stiff enough for an across the line start of a 2000 HP medium voltage motor.
Prior to purchasing the medium voltage VFD, they attempted to use a conventional medium voltage softstarter, but it wouldn’t work. Due to the high torque starting requirements, the starting attempt caused the power line to dip, shutting down other equipment in the oil field.
Since VFDs are able to produce much better starting torque and adjust the acceleration times, unlike soft starters, they lend themselves as a perfect solution for
these types of applications. In fact there many Toshiba medium voltage T300MVi VFDs being used as soft starters.The startup went well, and the customer was very satisfied with the medium voltage drive performance.
In general, when you start a motor across the line, the instantaneous current could get up to 1000 percent of the FLA. Softstarters give you the ability to reduce the instantaneous current to 300%. With a VFD you can bring the starting current below 100 percent of the FLA of the motor. As a result we were able to set up the VFD and run the compressor without causing any excessive starting amps draw on the line.
EMA sells and stocks the Toshiba medium voltage VFD, the T300MVi. EMA not only sells the T300MVi, but offers start up, preventive maintenance and field service repairs on these medium voltage drives along with others. For instance, we also repair the Siemens/Robicon Perfect Harmony medium voltage drives, WEG MW01 medium voltage drives, and the AB Powerflex7000.
Contact your nearest EMA facility (see the bottom of this page) or better yet, just hit any of the contact options on the right, including live chat.