Being good stewards of natural resources like water and energy while still maintaining or even improving productivity is an ever-growing challenge for business owners and operators in search of sustainable solutions. That’s why high efficiency equipment has become a more viable option than ever. Specifying engineers across a variety of industries, including the mining, industrial, commercial, municipal and agricultural sectors, want to understand how high efficiency systems will work for their application needs. Will these systems not only deliver financial savings but also perform reliably with steady operation – using resources more intelligently without sacrificing equipment life, maintenance and other operational concerns?
A growing solution for delivering higher efficiency with proven reliability is a pumping system built around a permanent magnet (PM) motor. PM motors are a proven technology many people use throughout their lives; automotive equipment, computer drives, vacuum cleaners and outdoor tools are just a few examples. The rotors inside PM motors are magnetized at all times due to the raw material selection and require no electrical power, making them more efficient – especially at reduced speeds and partial loads. PM motors operate more efficiently using rare earth magnets that perform with no slip. This translates into lower input power for the same output power, saving on operational costs every time the motor runs. In fact, running these in specific applications can provide energy savings that quickly offset additional initial investment costs. Motors with a 94% efficiency rating provide an investment payback of less than two years in most long- or continuous-run applications. This white paper takes a closer look at the benefits PM motors deliver in various applications.
Energy used by induction motors to produce work can reach up to 97% of its lifetime cost, while the purchase price represents as low as 2% of its total cost of ownership (TCO).2 In contrast, a pumping system powered by a PM motor and optimized with a drive runs much more efficiently. This is especially true in a setting that requires continuous duty, where these savings can add up
and will multiply over the years. PM motors run with an efficiency rate of up to 94% which is 10 to 12 points greater than a standard induction motor and delivers up to 21% energy savings when compared with its counterpart. The Hydraulic Institute rates the interior permanent magnet design as the best peak efficiency available when compared to any other motor constructions, including surface-mounted or even induction motors.
PM motors offer benefits whether the application requires constant or intermittent operation, since the PM rotor does not need to be magnetized. This concentrates all the power into motor shaft rotation for improved efficiency. Because of this power concentration, PM motor systems can run at a synchronous speed, providing improved hydraulic performance. With no slip, the motor speed is consistent and will not vary regardless of load.
When looking for greater long-term savings and a lower total cost of ownership (TCO) over conventional systems, there are several other factors to consider that add daily operating costs. In addition to the initial acquisition cost to purchase and transport the pumping system, TCO calculations for PM motors should include:
Here are examples of how permanent magnet technology impacts your energy costs per year and can deliver energy savings:
For any business using pumping equipment, reliability is critical. A more efficient pump is only as good as the consistent output it delivers. This is especially true in mining or municipal operations, where a down pump can have a catastrophic effect. PM motors in submersible pumping systems feature fewer moving parts as well as minimal above- ground components, which can mean easier initial installation and less scheduled maintenance down the road when compared to a vertical line shaft turbine installation.
When supplying water to homeowners and businesses, reliability equates to quality. PM motors should be National Sanitation Foundation/American National Standards Institute (NSF/ANSI) 61 certified and safe for drinking water systems to provide this peace of mind.
Benefits 1, 2 and 3 deliver cost savings that also add up to more overall sustainable operation. Lower electrical usage saves money for users, but also reduces the carbon footprint associated with the application. For example, in the mining dewatering setting operating at 12 hours per day, the mine site personnel observed an annual CO2 reduction equivalent to 32.3 tons in a year-- and avoided paying for nearly 42,000 additional kilowatt-hours. In the municipal setting running 100 horsepower equipment 10 hours/day, the energy efficiency improvements obtained by switching to this technology would be equivalent to replacing more than 304 incandescent bulbs (60W) with LED’s every year. Another way to look at it is the additional power required for the induction system is roughly 13.5 tons of CO2. According to the EPA it would take almost 15 acres of forest to sequester the added carbon dioxide every year.
In addition, PM motor systems offer quieter operation to reduce noise pollution when compared to above-ground pumping sets, minimizing their impact on people and the surrounding environment.
Working hand-in-hand with sustainability is resiliency, or the ability to adapt and overcome unforeseen environmental conditions. For example, with the effects of climate change and warmer temperatures, many drillers are having to go deeper to access groundwater. In Dallas, groundwater used to reside at 600ft and now must be pulled >1,000ft. In Lubbock, Texas a pivot irrigation sprinkler used to be supplied by three wells and now requires +10 wells. These situations equate to additional energy requirements that could be partially or completely offset with PM motors.
PM motors provide considerable benefits in submersible applications over induction motors. If you are currently running an induction motor in a submersible pump and replace it with a PM motor, the PM motor will win every time in terms of less overall cost of ownership, more efficient operation, better performance and less downtime. Consider:
These are just the beginning of the benefits owners and operators experience with PM motor technology. It is also an efficient alternative to vertical line shaft turbines and submersible systems powered by traditional induction motor designs.
PM submersible motors typically have 4-poles, whereas an induction motor will rely on 2-poles.
This requires the motor to run at 120 Hz to achieve 3,600 RPM. VFDs are the only suitable motor control device that will allow a motor to run above the power line frequency. Today, more full-service manufacturers offer reliable solutions that range from 4-inch motors up to 300 horsepower using 10” submersible motors.
As technology progresses, manufacturers have also come a long way in providing cost-effective solutions that are built around variable frequency drives (VFDs) engineered to operate with both induction and PM technology rather than custom ones. This also delivers versatility and allows the units to serve multiple industries, applications and job requirements, such as:
Select VFDs are optimized to seamlessly be paired and perform with PM motors. In the past, variable frequency for these types of installations led to an intimidating and complex setup process; now, new solutions have been engineered to deliver ease-of-use. In some cases, you might experience a setup that feels as intuitive as installing a plug-and-play drive.
VFDs are the most popular electronic device used to vary the speed of a pump, and for good reason. PM motors have no slip and are designed to run with a synchronous speed at their rated voltage. This means you are not compromising speed for efficiency. When running a PM motor with a VFD, you can enhance and expand your pump envelope by gaining optimized efficiency. A PM motor paired with a VFD delivers not only energy savings and protection but also advanced speed control and soft start that maximizes the system’s life and mitigates maintenance costs throughout its lifespan. In addition, VFDs that have been optimized and designed for water systems will support the prevention of a dry-well scenario, protect against leaks and electrical surges, and reduce stress on plumbing thanks to its pipe-fill mode.
High efficiency pumping systems with PM motors are offered in various sizes and can easily grow with a user’s needs. Getting the system from one manufacturer can help with this compatibility and scalability. A single system manufactured and shipped from a single source will allow for simple startup, compatibility with various application types, optimized performance and extended system life. Some offer service options to ensure users are backed up for sizing and selection, as well as setup. Regarding scalability, users do not have to compromise efficiency when the system needs to grow.
Pumping systems that utilize a PM motor are becoming more widespread, due in part to their functionality across a wider range of pumping application needs. When paired with a VFD, they offer easy set up features and optimized operation, helping owners and operators benefit from more efficient system operation and cost savings that continue to add up throughout the entire
lifecycle of the system.
Franklin Electric is a global leader in the production and marketing of systems and components for the movement of water and fuel. Recognized as a technical leader in its products and services, Franklin Electric serves customers around the world in residential, commercial, agricultural, industrial, municipal, and fueling applications. Franklin Electric is proud to be named in Newsweek’s lists of America’s Most Responsible Companies and Most Trusted Companies for 2022.