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Shop for thousands of Motion Controls Products Online at Servo2Go.com November 11, 2016

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Respected by customers as a premiere source for High Performance Automation and Motion Control Components & Systems, Servo2Go specializes in Automation & Motion Control Systems & Components including: Servo Motors & Drives, Stepper Motors & Drives, Automation & Motion Controllers, Positioning Systems & Actuators, Gearboxes, Couplings, Brakes, Encoders, Tachometers, HMI’s & Operator Displays, AC/DC Motors & Gearmotors, PLC’s and Embedded Controllers all supported via extensive product selection, just-in-time & consignment inventory, dedicated customer service and technical engineering support.

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Servo Motors and Horsepower Rating March 27, 2015

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Reprint of TrueTech Specialty Motors March 26, 2015 Blog

Servo Motors and Horsepower Rating

Servo Motors are not usually rated in Horsepower because:

  • Servo Motors are usually used in incremental motion applications where the speed is frequently (and often rapidly) changing and delivered torque ranges from near nothing to brief periods of high peaks with an average of up to the continuous motor rating. These motors usually have a low inertia to power ratio.
  • Motors that are typically rated in Horsepower are usually used in applications where the motor runs at a constant speed (and fixed input voltage) and delivers a slightly varying torque. These motors usually have a high inertia to power ratio.

Certainly, a Servo Motor CAN be rated in Horsepower but it has to be at a specific load point that is at the motor’s continuous torque rating and a specific speed within the motor’s speed range. The bus voltage of the driving control also has to be known.

Power is a value that cannot stand by itself while specing out a motor and in the physical realm (Power = Speed * Torque). When you are looking at getting a motor’s parameters defined with power, it is necessary to provide speed and/or torque values. You can calculate one of those three variables when provided with the other two. Keep in mind that BLDC (servo) motors have various modes of operation and the power of the motor in use could be lower, or even potentially higher, depending on the application. For example, two motors continuously rated at 1 HP, one motor run at 1000 RPM and the other 15000 RPM, would definitely have at a minimum different voltage constants and physical components constructing the motor.

Horsepower is a Torque – Speed product

If the two values are not “fixed”, Horsepower becomes a slippery value. A handy conversion that is easy to remember is that 1 HP = 1,000,000 oz-in-RPM. Knowing this, a motor with a label rating of 1/2 HP at 1750 RPM (common AC motor) can deliver up to 285 oz-in (17.85 lb-in) (1.49 ft-lb) of torque. That would be a fully loaded rating. If the motor is running at less than rated load, it is not delivering 1/2 HP.

Similarly, a Servo Motor typically has a Continuous Torque rating, a Peak torque rating, a Ke, and a maximum operating speed. It may have a torque/speed curve based on a driver bus voltage and the continuous torque rating. A Horsepower rating for that motor could be the point on the curve where the speed-torque product is at its highest. However, if the motor is run slower or faster than this point, or the torque is lower than the continuous, the HP output will be lower.

Consequently, a typical servo application wherein the motor is expected to run at various speeds, directions, and torques, a Horsepower rating is essentially meaningless and the torque-speed curve is of greater value. However, in a power transmission application where the motor runs at a fixed speed and required torque is a specific maximum value, a Horsepower rating is of value.

 

Tags:  HP Rating, Servo Motor, Servo Motor Horsepower Rating

White Paper: Selecting a Brush-Commutated DC Motor February 11, 2015

Posted by Servo2Go.com in Technical Support Information.
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BASIC PARAMETERS

Permanent magnet direct current (DC) motors convert electrical energy into mechanical energy through the interaction of two magnetic fields. One field is produced by a permanent magnet assembly; the other field is produced by an electrical current flowing in the motor windings. The relationship between these two fields results in a torque that tends to rotate the rotor. As the rotor turns, the current in the windings is commutated, or switched, to produce a continuous torque output.

Brush DC motors can be operated over a wide range of voltages, speeds, and loads. Output power for a brush DC motor is a product of speed and torque; input power is a product of the applied voltage and motor current. The first step in motor selection is to decide if you are going to need a gearbox or not. This will typically depend on your maximum required load speed. A good rule of thumb might be to use a gearmotor if your maximum speeds will be below 1000 RPM, and use only a motor if your maximum speeds will be above 1000 RPM.

Pittman's Brush DC Motor Family

Pittman’s Brush DC Motor Family

If you are going to use a gearbox, start by selecting one that meets the torque requirements of your application. Gearboxes are usually rated by their maximum allowable output (load) torque. Once you have chosen a gearbox type, the appropriate ratio must be selected. Determine the ratio by dividing the maximum acceptable input speed to the gearbox by the maximum desired output (load) speed, then choosing the closest available ratio. Acceptable gearbox input speeds vary, but are typically on the order of 6000 RPM. Calculate the motor speed and torque requirements using the following equations:

  • WM = WL x N and TM = TL / (N x n)
    where WM = Motor Output Speed
  • WL = Load Speed
  • N = Gear Ratio
  • TM = Motor Output Torque
  • TL = Load Torque
  • n = Gearbox Efficiency

Once the motor requirements have been determined, choose a motor type and frame size capable of producing the required motor torque. For continuous operation, select a motor with a continuous torque rating greater than that of the required torque. For intermittent operation with a sufficiently short on-time, select a motor with a continuous torque greater than that of the rms value of the required torque.

Motor manufacturers will provide continuous torque ratings for their motors under certain operating conditions, including a specified ambient temperature (often 25 degrees C. or 40 degrees C.) and thermal resistance (dependent on whether a heat sink is utilized.) Take care to read the fine print when comparing continuous torque ratings as they may need to be adjusted if these assumptions do not match your actual operating conditions.

After a frame size has been selected, the proper winding needs to be specified. Generally, voltage and torque will be known values, and speed and current will need to be determined. The best winding choice will be that which comes closest to providing the desired speed and current draw given the supply voltage and load torque. The governing motor equations to determine speed and current follow:

  • W = (VS – I x Rmt) / KE and I = TL / KT + INL
    where W = Speed
  • VS = Supply Voltage
  • I = Current
  • Rmt = Motor Terminal Resistance
  • KE = Back-EMF Constant
  • T = Load Torque
  • KT = Torque Constant
  • INL = No-Load Current

While these equations are suitable for most applications, it is important to realize that they are only the basic formula and do not take into account thermal considerations. Motor heating will alter some of the parameters in these calculations, including resistance, torque constant, and back-emf constant. Accounting for these effects adds significantly more complexity to the process. Finally, when going through any calculations, make sure to maintain consistency among units of measure.

COMPONENT FEATURES

“Off-the-shelf” brush-commutated DC motors are the exception, rather than the rule, and they are frequently customized to meet specific design and performance criteria for an application. Among those components typically specified:

Optical Encoders: Since closed loop servo applications require velocity and/or position feedback, common motor options include incremental optical encoders, which supply accurate position, velocity, acceleration, and direction feedback for precision motion control. Encoders can be added to any motor or gearmotor with wires or side-exiting power terminals and can be metal-housed or open air. They can be factory-mounted or prepared for mounting in the final stages of end-product assembly. Encoders are usually specified with either two- or three-channel, TTL compatible quadrature outputs. The maximum frequency, which limits the maximum operational speed, is typically 100 KHz. In a three-channel unit, the third channel provides an index signal or pulse once per revolution of the codewheel.

Another encoder option, the rotary pulse indicator (RPI), is a single-channel unit with open-collector or TTL-compatible outputs. RPIs are low-cost solutions for appliance applications that need 120 counts per revolution or less without direction-sensing capabilities.

Shafts: The shaft of any motor can be customized with a flat, journal, cross hole, keyway, slot, groove, gear, or pulley. These options can be combined to meet application requirements. As examples, a cross hole can allow a pulley to be pinned to the shaft, or a journal can include a groove. A variety of other combinations are possible. Shaft material can be customized from the standard 416 Stainless steel to other grades, such as 303 and 316 Stainless with different Hardness ratings. Standard and common optional shaft diameters include a variety of sizes from 4mm to 8 mm and from 5/32-inch to 3/8-inch.

Gearheads: Gearheads increase output torque and decrease speed. These functions and their efficiency vary with different models and applications. For most applications a spur gearhead is flexible enough to meet specific torque, noise, and cost requirements. Standard spur gearheads feature sintered nickel-steel gears, which provide moderate power handling with average audible noise. The sintering process allows for close tolerances (AGMA Q7-8) at a low cost. The sintered gear functions as a lubrication holder and helps dampen sound. When more strength is required, a hybrid cluster (an assembly of a cut-steel pinion and a sintered gear) or precision cut steel gears can be chosen. Other gearhead options include planetary gearheads for lower backlash and much higher torque or Delrin (moldable polymer) gears that produce less noise than sintered gears.

Wire and Cable Assemblies: Custom wire and cable assembly options are designed to speed motor installation and boost component reliability. Almost any connector style and wire type can be specified for motors, gearmotors, and encoders.

EMI/RFI Suppression Components: A number of cast and stamped component solutions have been developed to reduce the amount of electrical noise generated by a motor. For low-frequency RFI (typically below 30 MHz) capacitors are generally effective, and there is an inverse relationship between the value of the capacitor and the attenuated noise frequency. Capacitors installed by the motor manufacturer enable strategic placement inside the motor frame for optimum filtering as close to the noise source as possible. For high-frequency noise (generally above 30 MHz) ferrite beads can help reduce RFI. A combination of ferrite beads and capacitors provides the most effective suppression by creating a low-pass LC filter that is inductive-capacitive at low frequencies and dissipative at high frequencies.

Mounting for each component may vary from slipping ferrite beads over wires to soldering chokes near the motor terminals, depending on the best solution for the application.

Brakes: Developed as a safety and energy-saving feature, rear-mounted power-off and power-on electro-magnetic brakes prevent a motor or gearmotor from rotating freely. Brakes typically are offered for 16 and 40 oz-in static torques and 12, 24, 28, 48, and 90 VDC operation, although other voltages, including 120 VAC, are available. A power-off brake stops a motor when power is removed and releases the motor when power is reapplied. In low-duty applications, the brake saves energy by maintaining a known motor position without power. An added safety feature is that should power be lost while the motor is lifting an object by pulley or lead screw, the brake will lock the motor and prevent the object from falling. A power-on brake holds the motor in place upon application of power and releases the motor when power is removed.

DEALING WITH EXTREMES

When brush-commutated DC motors are used to drive gears or pulleys, avoid excessive side loads. These can push a motor to an extreme and lead to motor failure. If side loads will be present, ball bearings are usually recommended. Environmental conditions will impact, too, on effective brush DC motor operation and performance. For example, the moisture in the air acts as a lubricant and, where humidity is low, the resulting lower lubrication will accelerate brush wear and shorten motor life. (Special brushes are designed to solve this problem.)

AVOIDING PITFALLS

  • Know the proper rating of the motor for an application and recognize and understand the importance of continuous operation vs. duty cycle.
  • Do not press fit components on a motor’s shaft (in any direction) without proper support at the other end of the shaft. This action could lead to motor failure.
  • Do not apply adhesives or other foreign material directly to shafts that could contaminate the bearings. These could negatively affect performance. If such materials are to be applied, it is generally advised to apply them to the component to be secured to the shaft to reduce the chance of contamination.
  • Consult with your motor manufacturer before, during, and after a motor is specified for an application.

STANDARDS AND REGULATIONS

NEMA publications represent the most relevant sources for standards relating to traditional motor products and devices. Other standards include ANSI and IEC for rotating machinery, as well as IEEE standards for motor-related test procedures. A “CE” designation assures compliance with appropriate standards for those products used in the European marketplace. In addition to product standards, a set of quality oriented standards applies to motor suppliers. Those manufacturers that have achieved ISO certification demonstrate documented adherence to procedures and operations consistent with international quality standards.

MOTOR FAILURE MODES

The primary cause for failure of brush-commutated DC motors over time is ongoing brush wear. The traditional method for mounting copper or silver graphite brushes in motor assemblies has been to solder the brushes onto standard cantilever springs to enable the required constant contact with the commutator. This conventional spring design, however, carries inherent drawbacks as force levels diminish over time, and motor failure can result.

The problem can be overcome by housing the brushes within a specially designed cartridge and utilizing torsion springs to ensure desired even force over the life of a motor. The cartridge, which fits into the motor base, consists of a two-piece, high temperature plastic snap-together assembly in which each of two brushes is seated securely within its own specially constructed slot. This design effectively restricts the brushes to traveling in a track in a desired linear motion.

The cartridge design further provides for an ideal region of pressure (6-8 lbs. psi) for the brushes to withstand the detrimental effects of mechanical wear. Other typical causes that can result in motor failure include motor overloading, contamination of the armature, and electrical or mechanical malfunctions. There are many others, depending on motor design, operating parameters, and in-use service and safeguards.

COST SAVINGS

Users can save money (and headaches) at the outset by partnering with a quality motor manufacturer from the very beginnings of the design stage. This will minimize (and likely eliminate) costly mistakes and ensure that a motor performs as intended and required in an application.

This early involvement also can open a window to available motor features and options, which could help initially to reduce labor and material-handling costs for the customer and provide for easier motor installation.

View our Products: DC Mini Motors: 12V & 24V

For more information, please contact:

EDITORIAL CONTACT:
Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com

 

Tags:  DC Motor, Brush Motor, Servo Motor, Brush Servo Motor, Brush-Commutated DC Motor, Brush-Commutated Motor

Slotted vs. Slotless Motor Technology January 23, 2015

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Slotless vs. Slotted BLDC Motor

Slotless vs. Slotted BLDC Motor

When first introduced, brushless DC motors, despite their many advantages, were cast as a costly alternative to brush-commutated motors and were typically only specified for low-power applications where long life was the primary desired requirement. Without the mechanical brush-commutator mechanism that would wear and eventually result in motor failure, brushless motors could be relied upon to deliver performance over time. As for other advantages, conventional wisdom held that brushless motors provide high speed and fast acceleration, generate less audible noise and electromagnetic interference, and require low maintenance. Brush-commutated motors, on the other hand, would afford smooth operation and greater economy. In the past decade, though, brushless motors have gained broader appeal and greater acceptance in industry for a wider range of applications previously dominated by brush-commutated products, due in part to dramatic reductions in the cost and size of electronic components and advances in motor design and manufacturing.

At the same time, manufacturers have further sought to challenge conventional wisdom by improving brushless motor design in an effort to combine the traditional advantages of brush-commutated and brushless types. A noteworthy example of how far these innovations have progressed involves the slotless (instead of slotted) construction of the brushless motor’s stationary member, or stator.

The slotless stator design originated with the goal to deliver smooth running performance and eliminate cogging, which is an unwanted characteristic especially in slower-running applications (less than 500 rpm). The absence of cogging is, in fact, the most-often cited reason for selecting a slotless brushless motor…

Click on the link below to view this complete White Paper.

https://servo2go.com/information.php?menu=TS&page=10032

For more information, please contact:

EDITORIAL CONTACT:
Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com

 

Tags:  Servo2Go, slotted motor, slotless motor, BLDC motor, servo motor

New – High Performance Servo Motors from ElectroCraft September 10, 2014

Posted by Servo2Go.com in New Product Press Releases.
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New RPP Series of High Performance Industrial Servo Motors

ElectroCraft’s RPP series of industrial servo motors features high performance and extremely low cogging – for the most demanding servo applications.

ElectroCraft RPP23 Servo Motor

ElectroCraft RPP23 Servo Motor

The RPP series features a range of encoder, brake, cable and integral connector options.  The totally enclosed non ventilated package (TENV) meets demanding IP65 standards and is RoHS and CE compliant.

These high performance servo motors provide peak torque in excess of 2,200 oz-in (1,600 N-cm) and are available in a variety of windings from 48 VDC to 325VDC.  The RPP servo motors are fully compatible with the ElectroCraft Complete Power Plus series of line voltage servo amplifiers and PRO series DC input controller/amplifiers.

To learn more about the new RPP family of servo motors please click the link below:

https://www.servo2go.com/product.php?ID=105472&cat=

More information on all the NEMA Frame Brushless Servo Motor/Encoders from ElectroCraft can be found at the link below-

https://www.servo2go.com/search.php?search=ElectroCraft RapidPower&D=PROD

For more information, please contact:

Editorial Contact:

Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:   877-378-0249
www.servo2go.com

Tags:  Servo2Go, ElectroCraft, RPP23, Rapid Power Plus, Servo Motor, BLDC Motor

 

Did You Know? Synchronized Motion Using Encoder Following September 2, 2013

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Encoder following, which is also known as A/B Quadrature control mode, can be utilized on stepper and servo drives sold by Applied Motion Products.  An encoder is a feedback device most commonly found in servo systems where positional feedback is essential for closed-loop control. Incremental encoders are standard on all servo motors sold by Applied Motion and they may also be ordered pre-installed on our stepper motors and integrated steppers for use with our stall prevention and stall detection features.

But did you know that an encoder can also act as an input signal to control and synchronize the motion of two or more motors?

Because the output from an encoder is a series of pulses, consisting of an A and B channel, these signals are very similar to the Step Pulse & Direction outputs that are commonly found on a PLC or indexer. With a few simple configuration steps, an Applied Motion stepper drive or servo drive can be configured to accept these encoder pulses as a command source.

In motion control applications such as high speed insertion, line speed matching, adhesives application and labeling (all of which require one axis to be synchronized to another), this configuration can not only be very useful, but quite easy to set up and manage.  In those applications that require the secondary following axis to go faster or slower than the primary axis, the “Electronic Gearing” ratio can be manipulated to achieve this.

When configuring a stepper drive, the ST Configurator™ software is used to select A/B Quadrature as the signal type. When configuring a servo drive, Quick Tuner™ is used to make this selection. In both cases, the Electronic Gearing parameter (defined in units of steps per revolution), can be defined such that the motor following the encoder will run faster, slower, or at the same speed as the encoder itself. To illustrate this concept, picture a large machine equipped with a hand wheel connected to an encoder, which has been wired to a drive configured for encoder following. As the machine operator turns the hand wheel, the corresponding machine axis can be positioned at the desired rate of speed.

In more sophisticated control systems that require encoder following to be switched on only at specific times during the process, our Serial Command Language (SCL) can be used to issue commands to the drive to accomplish this.  This feature allows the system designer to synchronize, on demand, two or more axes of motion.

The FE (Follow Encoder) serial command can be issued to switch on encoder following while a drive is running in any other control mode.

Other SCL commands related to FE are:

  • EG – Electronic Gearing (sets ratio for following motor)
  • AC – Acceleration (controlled upon initiation of FE)
  • DE – Deceleration (controlled when FE is turned off)
  • DI – Distance (defined deceleration distance)

To learn more about SCL and Q Programmer, please visit our website.

For more information, please contact:

EDITORIAL CONTACT:
Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com

Tags:  Encoder Following, Applied Motion Products, Servo2Go, Step Motor, Servo Motor, Stepper Motor,

Reasons For Turning To Slotless Motor Technology July 15, 2013

Posted by Servo2Go.com in Technical Support Information.
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The slotless stator design originated with the goal to deliver smooth-running performance and eliminate cogging, which is an unwanted characteristic especially in slower-running applications (less than 500 rpm).  The absence of cogging is, in fact, the most-often cited reason for selecting a slotless brushless motor.

Click on the link below to view the complete White Paper.

http://www.servo2go.com/support/files/REASONS%20FOR%20TURNING%20TO%20SLOTLESS%20MOTOR%20TECHNOLOGY.pdf

More information on the BLDC Servo Motor Products from Servo2Go can be found at the link below-

http://www.servo2go.com/category.php?cat=10020&sub=10023

For more information, please contact:

EDITORIAL CONTACT:
Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com

NEMA 17 Frame High Speed Brushless Motor/Encoders March 17, 2013

Posted by Servo2Go.com in New Product Press Releases.
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ElectroCraft RapidPower high-speed brushless motors feature ball-bearing construction, dynamically balanced rotors, low vibration and low audible and magnetic noise.

ElectroCraft RP17 Brushless Motor

ElectroCraft RP17 Brushless Motor

By utilizing M-8 ceramic and rare-earth neodymium magnets, these BLDC motors provide the quick acceleration and consistent speed (up to 15,000 rpm) needed for applications such as centrifuges, fans and pumps.   Sealed ball bearings and reduced torque ripple from skewed magetization also ensure a smooth operation at any speed.

They are compatible with all three-phase brushless DC motor amplifiers and have optional 500 or 1000cpr encoders.

For more information on the Nema 17 brushless motors from ElectroCraft, click on the link below-

http://www.servo2go.com/product.php?ID=105478&cat=

For more information, please contact:

Editorial Contact:

Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:   877-378-0249
www.servo2go.com

Typical component forces in a drive system March 3, 2013

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Source:  Maxon Motor AG Formulae Handbook by Jan Braun

The force required to accelerate a mass of 1 kg by 1 m/s in 1 s has the unit kg · m/s², with the special unit name Newton (N) .

Typical Component Forces in a drive system

Typical Component Forces in a drive system

Handbook For High-Performance Brushless Servo Systems February 7, 2013

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Published by ElectroCraft,  12pages

Comparison of DC servomotors and brushless servomotors

ElectroCraft Handbook For High-Performance Brushless Servo Systems

ElectroCraft Handbook

The traditional permanent magnet DC servomotor has been the industry workhorse for many decades in highperformance servo drive applications.  The primary reason for this is that the DC servomotor is very easy to control using adjustable DC voltage.  A brief review of the operating principle of the DC motor illustrates this point (continued)…

Click on the link below to download this Free Handbook.

http://www.servo2go.com/support/files/ElectroCraft%20EC_Handbook%20for%20High-Performance%20Brushless%20Servo%20Systems-Final%20S2G.pdf

More information on brushless servo motors from ElectroCraft can be found at the link below-

http://www.servo2go.com/supplier.php?id=1189973790

For more information, please contact:

Editorial Contact:

Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:   877-378-0249
www.servo2go.com