South African industries facing rising energy costs, constrained capital budgets and increasing pressure to improve uptime can rethink how large motors are started, controlled and protected. Adrian van Wyk, CEO of Referro Systems, says a new approach to medium-voltage motor control allows several high-power motors to be managed using a single medium-voltage variable speed drive. This delivers significant reductions in capital expenditure, footprint and system complexity, without compromising reliability.
PowerFlex 6000T Drive SynchronousTransfer System design architecture.
Referro Systems, trusted local distribution partner for Rockwell Automation, is introducing the PowerFlex® 6000 medium-voltage ac drive with Synchronous Transfer Bypass (STB) to mining, water, utilities and heavy-processing operations across South Africa. According to van Wyk, the solution represents a step change in medium-voltage motor control design, particularly for sites that have a number of large motors operating in unison.
Conventional medium-voltage motor control systems typically rely on individual drives or starters for each motor. While effective, this approach can be capital intensive, space consuming and complex to maintain – especially in applications such as pumps and fans, where motors are often started one at a time rather than simultaneously.
The PowerFlex 6000T with Synchronous Transfer Bypass addresses this challenge by enabling up to 10 motors to be started and synchronised across the supply line using a single medium-voltage drive. The system supports combined currents of up to 3 000 A, with a maximum of 680 A per motor, across voltage ranges from 2.3 kV to 11 kV.
Once any motor in the system reaches operating speed it is synchronised to the fixed-frequency bus, and the drive is automatically freed to start the next motor in sequence should the process require this. This architecture reduces the number of variable speed drives required across a site yet still delivers all the benefits of variable speed control during continuous speed requirements, smooth start up, acceleration and deceleration control delivered by one variable speed drive.
Smoother starts, longer equipment life
Core to the solution is the Synchronous Transfer Bypass technology, which ensures that voltage, frequency and phase are precisely matched during the transfer from variable-frequency operation to fixed-speed operation and vice-versa.
This synchronous transfer enables a smooth, bumpless transfer. It eliminates the inrush current spikes, voltage dips and mechanical stress that typically plague traditional motor starting methods.
In practical terms, the benefits are substantial, says van Wyk. Softer acceleration reduces torsional stress on shafts, couplings and driven equipment, in turn extending asset life and reducing maintenance costs. Pressure surges are avoided in continuous processes such as pipeline compression and fans and pumps experience fewer process upsets and less unplanned downtime. Overall, this contributes to significant energy savings for equipment driven by the variable speed drive.
Fewer assets, lower lifecycle costs
By consolidating motor starts into a single drive system, organisations can significantly reduce both capital and operating expenditure. In some applications, customers have reported up to 80% fewer drives required compared to traditional architectures.
Reducing the number of drives not only lowers upfront costs but also simplifies maintenance and spares management. It creates a cleaner, more manageable automation environment with intelligence built in.
The PowerFlex 6000T with Synchronous Transfer Bypass also integrates into various modern digital architectures through networked connectivity, enabling direct communication with control systems. This connectivity supports predictive maintenance, enhanced diagnostics and improved visibility into motor and process performance.
For more information visit: www.referro.co.za
