Forty percent of the world’s electricity generated today is used solely to power electric motors. In addition, over 40 percent of such electricity is derived from burning coal/peat and another 25 percent comes from natural gas and oil. Electric Torque Machines (ETM) M-Series direct drive motors offer pump applications a highly efficient, lower cost alternative to the incumbent AC gearmotors.

Figure 1: Power consumption comparison showing a 29-54 percent reduction for the ETM Direct Drive system.
Pumps can now be driven directly by the motor, which eliminates the need for an inefficient gearbox and all the losses that go with it. Compared to the AC gearmotor system, ETM reduces power consumption by up to 54 percent. Commercialized in 2011, ETM has been delivering their motors to a variety of applications from conveyors to industrial fans, and recently extended its focus to include positive displacement pumps.
Peristaltic pumps require relatively high torque at low rotational speeds, typically in the range of 5 to 500 rpm, well below the direct drive capability for incumbent, conventional AC or DC motors. As a result, incumbent motors are operated at a higher speed (over 1000 rpm) and a speed reduction gearbox is necessary to achieve the required torque and rotational speed. These geared drive systems are large, heavy, inefficient, and the gearbox increases cost while causing a reliability and maintenance burden.

Figure 2: Speed/pressure operating range comparison showing ETM Direct Drive system with 10 times greater turndown ratio.
Compared to these conventional geared systems, ETM Direct Drive motors deliver high continuous torque at low rotational speeds, which eliminates the need for a speed reduction gearbox. This greatly reduces the drive system weight, size, temperature, and power consumption of the pump system while offering the user a wider operating speed range. ETM motor sizes cover a range of both peristaltic and hose pumps.
ETM’s motors use transverse flux technology with increased pole count and low resistance coils delivering 5-10 times more continuous torque by mass compared to conventional AC or DC motors. In addition, the higher losses in geared drive systems mean the conventional motors need to be oversized to meet the output power requirements.

Figure 3: Size and weight comparison—ETM M100 Direct Drive vs. AC motor with gearbox drive system.
As a result of this design, ETM drive systems have proven to be as much as 50 percent less expensive geared drive systems. One of our customers, a leading peristaltic pump manufacturer, was able to replace a 45-pound AC induction motor, gearbox, with an ETM Direct Drive system resulting in a 35-pound weight reduction.
Efficiency legislation is creating an ever-growing focus on motor and pump system efficiency. AC induction motors suffer from high losses in variable speed/load applications. As speed moves away from nominal RPM in conventional motors, efficiency can fall to less than 50 percent. Gear losses, caused by sliding friction and movement of viscous oil, further compound overall drive system power loss. ETM Direct Drive motors have very low coil resistance and high pole count, an ideal combination for efficient torque production at low speeds. Compared to the AC geared system, power consumption versus pump speed is reduced 29-54 percent for the ETM direct drive system (see figure 1).
Installation of AC gearmotor systems often requires an electrician to connect the controller to building mains while ETM Direct Drive systems come pre-wired with a 110V cable and plug. Simply plug into your building’s 110V power and you’re ready to use the motor; 220V systems are available as well.
Most AC geared peristaltic pump drive systems offer a maximum turndown ratio of 10:1 (i.e. max pump speed is 10 times greater than the min speed). This ratio is often limited by variable frequency drives used to operate AC induction motors. ETM Direct Drive systems operate from 5 to 500RPM, a turndown ratio of 100:1 (see figure 2). Testing has also shown that ETM Direct Drive systems are capable of operating at higher continuous loads. This also enables OEMs to replace many motor and gearboxes with far fewer ETM Direct Drive systems and results in simpler inventory management, improved working capital turns, easier replacement parts service, and lower inventory costs.
According to the sales leader of a major global peristaltic pump manufacturer: “ETM’s Direct Drive enables us to offer our customers a cost-effective pump system that’s significantly smaller and lighter than anything we’ve seen on the market.” ◆
Stephen Hogue  Based in Flagstaff, Arizona, Electric Torque Machines has been delivering its efficient, low cost motor technology for the past five years. Customers are using this innovative technology due to its ultra-high continuous torque density, which eliminates the need for extra parts (e.g. gearbox), thereby decreasing customer costs and system losses amongst various additional benefits. For more information, visit
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