Cut Energy Costs with MV Drives, Sync-Transfer Control

Industrial facility managers and engineers are always seeking out ways to reduce equipment costs, the space that equipment occupies and – usually most of all – the energy that the equipment uses. After all, U.S. companies spend over $165 billion annually to power their manufacturing plants.

Electric motors and motor systems in industrial and infrastructure applications (running things like pumps, fans, conveyors and compressors) are responsible for more than 50% of the world’s total electricity consumption.

Here’s the good news. Smart variable frequency drives (VFDs) offer the potential to dramatically reduce motor system energy use.

According to the Affinity Laws for centrifugal fans and pumps, reducing the motor speed by 25% lowers the motor’s energy consumption by approximately 60%. Decreasing the speed of a pump or fan motor by 50% reduces the motor’s energy usage by almost 90%. Plus, operating at lower speeds also extends the life of the pump and other driven equipment. So, using variable frequency drives to reduce the motor speed to the specific application requirement can deliver immediate energy savings!

Here's the other good news. Rockwell Automation offers another way for engineers to rethink asset utilization. Using PowerFlex^® medium voltage (MV) drives and sync-transfer control, engineers have an additional capital reduction and energy saving solution…

Reduce equipment costs

Unlike the traditional one-for-one VFD-to-motor architecture used in most plants, by using sync-transfer control, an engineer can use one MV drive to selectively control multiple motors, one motor at a time.

Sync-transfer control in oil & gas

In the oil and gas industry, for example, companies use hundreds of pumps and compressors to move crude oil and natural gas through pipelines from oil and gas fields to refineries or processing plants.

A typical pipeline station transports petroleum-based products. The total motor power ratings for the station depend on several factors, including viscosity, pipeline distance, flow rates required to meet schedules, etc. For a specific pumping station, perhaps the worst-case pumping capacity demand could be as much as 6711 kW (9000 Hp) in total. But rather than using one large pump, three 2237-kW (3000-Hp) pumps in series controlled by one PowerFlex medium voltage VFD offer greater asset utilization and pump-to-motor redundancy.

At times of peak process demand, the pumping capacity can be increased with the sync-transfer system. Likewise, the overspeed operation of the drive can capitalize on reduced peak energy rates – so more product is moved when utility rates are less.

Remote monitoring with real-time data

PowerFlex VFDs also provide real-time process control and data that helps make the difference between profit and loss.

For example, by connecting the VFDs to a facility’s control network, operators can discover that two connected pump stations in separate energy utility zones have noticeably different electricity rates. And the operators could then run the pump station harder in the zone with lower rates.

Even in one utility zone, the operators could find that energy costs are lower during off-peak hours and then adjust the system to capitalize on the lower rate.

Smart VFDs help reduce downtime

With a smart VFD, engineers can set analytic models to measure equipment speed or other characteristics. Plus, they can use remotely accessed data to identify potential maintenance needs. When examining three pumps that are running at the same speed, an engineer could notice that one pump has a lower load torque. As a result, a technician could be sent to investigate the issue. VFDs with remote data visibility help:

• Reduce downtime and maintenance costs
• See predictive life alerts based on embedded analytics for critical components
• Confirm drive component runtime hours and maintenance requirements

Plus, when PowerFlex 6000T VFDs are combined with FactoryTalk® Analytics™ GuardianAI™, operators get an expanded view into the health of plant assets, including:

• Predict and identify pump, fan or blower failures
• Get notifications of flow restrictions, cavitation, loose mounting, blade misalignments, bearing faults, etc.

Where medium voltage drives provide the most value

Energy-intensive industries, such as petroleum, metals, minerals, food, paper and chemicals account for over 50% of global industrial energy use and offer countless opportunities for smart motor control solutions.

PowerFlex medium voltage drives can control motors for pumps, compressors, conveyors, blowers, extruders, fans, mixers, cranes, hoists, chillers and propellers. And each application offers the opportunity to reduce energy use.

The opportunity to apply sync-transfer control for pumps in the water, wastewater, oil and gas industries is enormous. One Rockwell Automation customer in the energy industry uses more than 100 medium-voltage drives – and most operate sync-transfer systems.

Top 3 sync-transfer motor control benefits

Do more with less equipment. PowerFlex 6000T and PowerFlex 7000 VFDs with sync-transfer control help:

• Save energy. Combine the efficiency of the VFD with seamless sync-up and sync-down transitions and reap the energy-saving benefit of direct-on-line operation at optimum speed. Reduce peak energy charges. Reduce VFD power losses because the size and number of VFDs are reduced
• Save time. Reduce time and costs designing multi-drive systems – specifying, purchasing, shipping, installing, commissioning and maintaining additional VFDs
• Save money. Reduce both capital and operational costs. It costs less to buy, house, power and cool one MV drive with a sync-transfer system versus multiple variable frequency drives

Rockwell Automation has offered sync-transfer systems with medium voltage drives since 1989. Several hundred sync-transfer systems have been implemented worldwide.

By delivering precise motor control and real-time process data with predictive maintenance alerts, smart VFDs can help achieve your production goals. Learn about PowerFlex medium voltage drives online. There’s an MV drive solution that’s right for you.