servo motor

More efficient automation with explosion protection

Guest Contributor:  Frank Kaufmann, Bosch Rexroth

You think that drives for potentially explosive areas are complex to implement or technologically suboptimal? In this way you simplify your engineering and play in the first league on the automation side.

Are you automating in potentially explosive areas and tired of having to make compromises when choosing a drive solution? Regarding performance, intelligence, connection technology, …? In fact, it has not been easy to combine explosion protection, modern servo technology and efficient engineering. The common practice, including the declaration of conformity for the acceptance, is tedious and time-consuming. Especially if you have to design, have certified and apply a special enclosure for a non-ex motor. How much easier would it be if you could simply select a ready-to-install ATEX servo motor with declaration of conformity and the latest technology and immediately concentrate on the essential machine or plant construction? That’s exactly what you can do now.

First ATEX servo motor with single cable connection

Bosch Rexroth has developed the first ATEX-certified servo motor with single-cable connection in order to merge modern features such as high drive performance, simple integration into the machine, safety-on-board and i4.0 features into a complete solution. The new MS2E series is based on the MS2N standard series in terms of design and therefore achieves the same optimum values in terms of dynamics, precision and connectivity. It is also suitable for all ATEX applications up to device group II and device category 3 for gas (zone 2) and dust (zone 22). In practice, this means that an MS2E engine remains safe even if other safety-relevant or safety-specific components fail. If, for example, a combustible atmosphere is created due to a defective extraction unit, this cannot be ignited by the engine.

Fast and accurate design – with safety

Because time is money and errors cost time and money, the design within the IndraSize engineering tool is based on a virtually exact engine model. The result: the design of the MS2E corresponds exactly to the real operation. Do you want even more efficiency? With SafeMotion applications, you achieve the greatest possible machine safety thanks to high-resolution 20-bit single or multiturn encoders in SIL2 PLd. Additional practical options include holding brakes or shafts with feather keyway.

Compact power packs for downsizing

Without the right power density, an ATEX-certified engine is only half the fun. For this reason, Bosch Rexroth pays special attention to compact design. The extremely high torque density of the MS2E motors is up to 30 percent higher than that of the predecessor series – a new motor design with optimized electromagnetic design makes this possible. As a machine manufacturer, you benefit in two ways: You can solve your existing drive tasks with smaller motors and achieve more performance with the specified installation space. For the purpose of such downsizing, the self-cooled MS2E motors are available in five sizes with overlapping torque ranges up to a maximum of 119 Nm, each with up to five times the overload capacity and consistently low rotor inertia. What does this mean for your application? Full of dynamics and performance. A further plus point: because high-quality materials and optimized winding technology reduce internal losses, you can also work at higher speeds in continuous operation. As a result, you achieve significantly improved energy efficiency with sustainably reduced operating costs.

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The motor with single-cable connection reduces cabling, simplifies installation and accelerates time-to-market. (Photo: Bosch Rexroth)

Produce faster with fewer cables

You can use a real novelty in the Ex area if you use the characteristic single cable connection of the MS2E. The advantage: you need much less material as well as plug-in points and space in the cable duct. Fewer cables and interfaces also mean faster and more cost-effective assembly and installation. This reduces your costs and increases productivity – especially in applications with drag chains. Because they become lighter, you can drive at higher speeds.

Industry 4.0 without limits – the motor as sensor

If you also want to implement industrial 4.0 applications in potentially explosive areas cost-effectively and without additional components, you will be particularly pleased about this feature: As with the MS2N series, the MS2E can also be used as a sensor and data source. With a view to future requirements – keyword factory of the future – expand your intelligence in this way up to the engine. The individual measured values including saturation and temperature data are stored in the motor data memory and thus form the basis for various i4.0 applications. Because the IndraDrive controllers also access the data and process it in real time, you benefit from an additional increase in torque accuracy during operation, while the tolerance range is reduced to a fraction of the previously usual values.

Two problems with one solution

With the new ATEX motor MS2E, you have a solution: you guarantee maximum safety and play in the top league on the drive side, even in potentially explosive areas – in terms of power density, functionality and engineering. Together with the flameproof encapsulated MKE motor series, you now have a stringent overall portfolio at your disposal with which you can quickly implement your ideas – with identical performance and up to Zone 1. Interested? Learn more.

cropped-cmafh-logo-with-tagline-caps.pngCMA/Flodyne/Hydradyne is an authorized Bosch Rexroth distributor in Illinois, Wisconsin, Iowa and Northern Indiana.

In addition to distribution, we design and fabricate complete engineered systems, including hydraulic power units, electrical control panels, pneumatic panels & aluminum framing. Our advanced components and system solutions are found in a wide variety of industrial applications such as wind energy, solar energy, process control and more.

How to Calculate RMS Torque

Guest contributor: Hurley Gill, Kollmorgen

Question: How do I calculate RMS (Root Mean Square) Torque for a given axis motion profile in my application?

Answer:  Let’s take a look at the Root Mean Square (RMS) Torque and why it is important. Typically an axes’ motion profile is broken up into multiple segments, each segment is found to require a specific torque for a specific amount of time to complete the desired motion.  For example, this can include torque required to accelerate, traverse (against an external force and/or friction),  decelerate, and dwell.  Each of these segments affects the amount of heating the motor experiences and thus the equivalent steady state continuous requirement utilized to select the correct motor.  The RMS Torque calculation  considers not only the amount of torque, but also the duration of that torque (by segment).  Our example below illustrates how to calculate Trms of your motion profile.

The below motion profile would be broken up into eight (8) different segments, each with a required torque Tx and time tx.

Motion Profile with Segmentation

To calculate Trms, use this equation:
 RMS Torque Formula

Where T1 = torque required by and during segment 1, and t1 = time duration (t1-t0) of segment 1, etc..  Note the additional torque required by the motor to over come some external/thrust force (greater than friction alone) during segment 2, and the lack of this required torque  during the dwell segment 4 and 8.

Going back to the example motion profile above and the chart of that motion profile:

Motion Profile Table with Segmentation

Therefore, if you do the math – and we will spare you writing this into a very long equation, the result is:

Trms =  RMS Example   = 2.74 lb-ft or 3.715_Nm (1.35582_Nm/lb-ft.)

Conclusion:  We hope that this tutorial has helped you!  If you have questions about this or other calculations,  or any automation related problem you may be having, please contact the motion control and programming experts at CMA/Flodyne/Hydradyne.

cropped-cmafh-logo-with-tagline-caps.pngCMA/Flodyne/Hydradyne is an authorized  Kollmorgen distributor in Illinois, Wisconsin, Iowa and Northern Indiana.

In addition to distribution, we design and fabricate complete engineered systems, including hydraulic power units, electrical control panels, pneumatic panels & aluminum framing. Our advanced components and system solutions are found in a wide variety of industrial applications such as wind energy, solar energy, process control and more.