Medium Voltage Drives
High-capacity drive systems for medium voltage motors in heavy industrial and utility applications.
About Medium Voltage Drives
A medium voltage (MV) drive controls the speed of large motors that run directly on 3.3 kV to 11 kV supplies. At these ratings, a low-voltage drive would need a step-down transformer and very heavy cabling, so an MV drive is used to vary motor speed directly at the motor's own voltage — typically on large pumps, fans and compressors where the energy at stake is significant.
Microtech supplies the Amtech Electronics Axpert-Hivert series MV drive. It connects multiple power cells in series, fed through an input transformer, to produce the medium-voltage output directly. Amtech describes the design as low-harmonic and states that it runs standard asynchronous or synchronous motors without an output filter or motor derating.
MV drives are application-engineered rather than picked from a price list. We review the motor data, supply fault level, duty cycle, site space and cooling, then work with the manufacturer on the configuration, installation and commissioning.
Key specifications
| Output voltage classes | 3.3 kV, 4.16 kV, 6.6 kV, 11 kV (3-phase, 50/60 Hz) |
|---|---|
| Power range | 250 kW to 12,500 kW (270 to 16,750 HP) |
| Topology | Series-connected power cells with input transformer |
| Efficiency (manufacturer data) | About 98% for the drive; about 96% including transformer |
| Communication | RS-485 Modbus RTU standard; PROFIBUS DP and industrial Ethernet optional |
| Redundancy | Duplicated control power supplies; optional power-cell bypass |
| Control | Local, remote and host-computer control; fibre-optic link to power cells |
Features & benefits
- Runs standard MV induction or synchronous motors without an output filter
- Low-harmonic design (per manufacturer data)
- Optional power-cell bypass to keep running at reduced output if a cell fails
- Fibre-optic communication between control and power sections for isolation
- Modbus RTU as standard for plant DCS/SCADA integration
- Application study and site coordination handled with the manufacturer
Where it’s used
- Large water supply and irrigation pumps
- Induced and forced draft fans
- Process compressors
- Cement, metal, paper and sugar plant drives
- Mine ventilation and dewatering
Standards & compliance
Medium Voltage Drives — FAQs
When does an MV drive make more sense than an LV drive?
Once motor ratings run into several hundred kW, MV motors and drives keep currents and cable sizes manageable. If your plant already has 3.3 kV, 6.6 kV or 11 kV motors, an MV drive controls them directly without stepping the voltage down.
Can an MV drive be fitted to an existing motor?
Often, yes. According to Amtech, the Axpert-Hivert can drive standard MV motors without an output filter or derating. We still review the motor's age, insulation and cooling before confirming.
What information do you need to quote an MV drive?
Motor nameplate data, supply voltage and fault level, the driven load and its speed range, duty cycle, and the space and cooling available at site. A single-line diagram helps.
