EMA specializes in Medium Voltage Variable Frequency Drive maintenance, service, and repair and after over 35 years, we’ve seen every make and model. One of the most prominent is the Toshiba T300MVi (now obsolete) and the T300MV2; for an overview of Toshiba’s MV Drive, see here. Like many Medium Voltage VFDs, Toshiba utilizes a quick-change power cell structure, which allows users to minimize downtime. The DC Link and inverter components are all housed within the cell itself, so the majority of problems experienced with these drives are cell related. On standard 4160V drives, there are 3 power cells per drive, one for each output phase. The advantage of this is that they are interchangeable phase-to-phase. For example, if your drive experiences a U phase cell error, the cells in the V and W phases are the same so they can be swapped to the U phase to determine if the problem is the power cell or something else. We highly recommend keeping at least one spare cell so that when you have a failure, you can swap out the cell with your spare, and be back up and running.
**Note: These power cells work inside the Toshiba T300MVi, the Toshiba T300MV2, and the TMEIC Dura-Bilt 5i; each model uses identical cells.**
These power cells are complex, and it is not recommended to field repair them. However, at EMA’s shop facilities, we’ve developed extensive load test stands, critical parts, and a knowledge base that allows us to repair any size Toshiba Power Cell. Many customers choose to repair their cells instead of replacing them with new because repair is significantly less expensive (new power cells are very pricey).
There is a mechanical component to repairing these power cells as the larger frame sizes weigh close to 950 pounds! The heatsinks needed to properly dissipate heat are filled with a liquid that aids in heat transfer, which is very efficient but adds weight and makes them sensitive to mechanical damage.
Toshiba uses oil filled capacitors for the DC Link of their power cell which have a much longer useable life than electrolytic capacitors that are used by other manufacturers, so we rarely encounter DC Link capacitor issues. Here are some of the most common failures we see:
- Mechanical Damage – As referenced above, we see a lot of mechanical damage due to improper handling and/or transport.
- Blown IGBTs – IGBTs are the devices that switch on and off to create the output to the motor and since the Toshiba drive has a multi-step topology, there are several IGBTs per cell as well as their associated fly-back diodes.
- Driver Boards – The IGBTs are driven (turned on and off) by the circuitry on the driver boards; if these experience failure, it is likely to fail its associated IGBT as well.
- Fiber Optic Issues – In order to isolate medium voltage from low voltage panels, it is very common for fiber optics to be used in Medium Voltage Variable Frequency Drives. These fibers are very sensitive to dust, debris, and bending. If these fibers become nicked or broken, the cell can issue a number of faults.
- Power Supply – There is a +15V power supply that powers the driver section and many of the ICs that run the cell. That power supply is easily changed but a common failure item. We often change this as a precaution whether it is bad or not.
- Voltage Detect Board – There are several of these small, resistor boards through the cell. We regularly see those resistors open or out of tolerance which gives the drive improper feedback, leading to faults.
Each cell is fully tested using a Toshiba Medium Voltage VFD running a motor, and to pull additional current we test them on a load bank to pull the rated current of the cell.
Do you have Toshiba power cells that need repair or refurbishment? Let us help you! Our standard turn around time on power cells is 4 weeks, not 6 months like the manufacturer. We have RUSH repair available too. Call Us, Email Us, or use the chat function on our website to talk with someone about getting your power cells repaired.
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