MPL Servo Motors
MPL (Low Inertia) servo motors from Allen Bradley are highly efficient and compact motors that are used for applications that demand motion sensitivity owing to significantly low rotor inertia. These motors have a high torque density (torque with respect to either weight or volume). These motors are brushless and are available in 9 different frame sizes. Premium permanent magnet is used in the construction of these motors. These servo motors are used with a range of Allen Bradley drive series (discussed later). MPL servo motors are ideally used for applications like assembling electronic components, packaging, material handling in different industries, automotive, and metal forming industries.
Mechanical and Electrical Specifications
Rotor and Rotor Magnets
MP Low Inertia servo motors are brushless AC motors. These motors are synchronous motors (recall the fact that magnet is present, no need for induction). For rotor flux production, their rotors are equipped with rare earth magnets which are premium in quality, and high in energy. These magnets pave way for quicker acceleration. Magnets on the rotors of MPL servo motors might have 8 different stack lengths (1 inch to 8 inch and corresponding codes as multiples of 10).
Rotors of these motors have threaded holes at their shaft end.
Stator Winding
Stator winding, which hugely decides the weight of the machine, is the major factor in determining torque and power density. To keep torque and power density high in MPL servo drives, stator winding is also made using innovative technology, and quality material is used for insulating this winding. Powerful rotor magnets and advanced stator windings make this motor provide 40% more torque (w.r.t. size) than conventional motors. This stator winding is also helpful in better heat management.
Motor Connectors and Cables
MPL servo motors can either have a connector that is a circular bayonet, and it faces a shaft (code 2) or these motors could come with a DIN connector that can rotate up to 180 degrees for ease of use. This connector is SpeedTec circular connector (code 7).
MPL servo motors also have brake (or power) connectors and feedback connectors as motion-sensitive applications need them. The supplier of this product will not provide auxiliary feedback, motor feedback, and I/O connector kits as accessories to the buyer.
Cables provided by the factory manufacturer will have standard length. These cables have appropriate sealing to ensure that the motor achieves promised environmental ratings as well as shield termination. These cables meet specifications and requirements of the following standards: NFPA 79 (National Fire Protection Association code 79) compliant, DESINA cable jacket coloring, tray cable rating, 600V insulation rating, RoHS and REACH, UL-Listed. Customers can also go with the option of designing their cables. For this purpose, kits are made available by Rockwell Automation. The construction of the cable would also affect the Electromagnetic Compatibility (EMC) of the system so extreme care is needed while constructing the cable. Shield of either type of cable would need grounding; it could be hazardous otherwise.
Allen Bradley directs its user that connector housings in the case of M40 and M23 can be rotated to make connector placement in a rearward direction. While connector housings for M58 must be removed physically and placed back in 90 degrees increments.
Shaft Seal
Not all servo motors of the MP Low inertia series come with a shaft seal. The user has to decide if, for some applications and the environment, a shaft seal is needed or not. The shaft seal will ensure that dust particles and moisture content does not enter motor bearings. Moreover, the type of use will also determine the frequency or duration of maintenance and replacement of shaft seals because these wear with time. Allen Bradley recommends users of these motors to inspect and maintain this component regularly – typically every 3 months but not to go beyond 12 months.
For these servo motors, nitrile is used to build shaft seals. For smooth operation of the shaft seal, a lubricant is included in the accessories package. To lubricate the shaft seal, the use of a shaft seal kit is recommended provided by Rockwell Automation. For different servo motors in the MPL series, different shaft seal kits are available, e.g., for motor catalog numbers MPL-A15xx and MPL-B15xx, the shaft seal kit with catalog number MPL-SSN-F63F75 is recommended, while for motor catalog numbers MPL-A3xx and MPL-B3xx, the shaft seal kit with the catalog number MPL-SSN-A3B3 is suggested, and so on. Furthermore, Rockwell Automation recommends its users use its shaft seals. If the owner uses shaft seals from any other company, then any sort of warranty (implied or direct) is not entertained by Rockwell Automation.
The presence or absence of a shaft seal will also determine which standards the product will comply with (discussed later in detail).
Mounting Dimensions
For MPL servo motors, the IEC72-1 standard for rotating electrical machines is complied with while making mounting dimensions. Indirectly, it covers frame numbers all from 56 to 400 and flange numbers ranging between 55 and 1080. Their mounting flanges have free mounting holes of type FF.
Frame Sizes
Allen Bradley has used novel design techniques (e.g. while designing stator winding, choosing winding insulation, placement of magnets, choice of magnets, etc.) to keep the size of MPL servo motors as low as possible. As mentioned, motors from this series of Allen Bradley products are available in nine different frame sizes – all being compact and sturdy. These frame sizes and the corresponding codes are as follows:
- Code 15 indicates a frame size of 63 mm
- Code 2 indicates a frame size of 75 mm
- Code 3 indicates a frame size of 100 mm
- Code 4 indicates a frame size of 115 mm
- Code 45 indicates a frame size of 130 mm
- Code 5 indicates a frames size of 165 mm
- Code 6 indicates a frame size of 215 mm
- Code 8 indicates a frame size of 265 mm
- Code 9 indicates a frame size of 300 mm
Encoders and Feedback
Servo motors from the MPL series are used for those motion applications which require high performance. High-resolution encoders are also there to determine the accurate position of the rotor. Thus, these motors have efficient high-resolution feedback systems. This feedback could be either single turn (-E and –S) or multi-turn (-V and -M) through the encoder. In single turn feedback systems, the absolute position of the rotor is fed back to the controller in just one turn while maintaining high resolution. On the other hand, 4096 turns are needed to provide high-resolution feedback in multi-turn encoder systems. This feedback would also be the absolute position of the motor rotor.
Motors with the –M and –S code can make up to two million counts in one revolution while motors with code –E and –V give up to two hundred and sixty counts in one revolution – all giving smooth performance.
Motors in the MPL series also have the option of an incremental encoder (with Code ‘H’) and resolver (with code ‘R’).
Brake Availability
MPL servo motors could either have a 24V DC brake (code 4) or no brake at all (code 2). If the brake is present, it will keep the motor shaft still or hold it at 0rpm (revolutions per minute) unless applied torque remains below the rated holding torque for the brake. Anyhow, this brake is not to bring the motor to a stop.
For disengaging this brake, a separate power source is needed. This power can be provided by a servo motor controller or an operator control which could be manual.
On-board Memory for Commissioning
To know motor parameters, the system doesn’t need to perform commissioning of these MPL servo motors from scratch. Instead, these motors are equipped with a memory unit to store the identity of the motor. So, upon startup, the system could identify motor, and commissioning time could be reduced significantly.
Voltage Class
Motors from the MPL series are grouped into two classes based on operating voltage: 200V class and 400V class. In the catalog number MPL-xxxxxx-xx7xAA, the first 'x' is to distinguish between voltage classes. Because of two options for voltage, A is for 200V class of motors and B is that for 400V class motors.
Compatibility for Drives
The motor, being the crucial part of a drive system, needs to be designed while considering application requirements and characteristics of other components in the drive system. In other words, the motor’s compatibility with the drive should be kept in mind. MP Low inertia servo motors are compatible with the following Allen Bradley drive systems: Kinetix 5500, Kinetix 6200, Kinetix 6500, Kinetix 6000, Kinetix 300, Kinetix 350, Kinetix 2000, Kinetix 7000, and Ultra3000.
Torque Output
Servo motors from the MPL series give its users a wide range of options for torque. Different motors from this series are capable of providing continuous stall torque in the range of 0.26 to 163Nm while peak stall torque goes up to 278Nm (e.g. catalog number MPL-B980B) starting from 0.77Nm (e.g. catalog number MPL-A1510V). Servo motors in MP Low inertia series give 40% higher torque output than that of other servo motors of the same size.
Speed Output
Servo motors of the MP Low Inertia series can attain speed up to 8000 rpm (revolutions per Minute). Other available options for rated speeds and respective codes are given below.
- Code B indicates a rated speed of 1000 rpm
- Code C indicates a rated speed of 1500 rpm
- Code D indicates a rated speed of 2000 rpm
- Code F indicates a rated speed of 3000 rpm
- Code H indicates a rated speed of 3500 rpm
- Code J indicates a rated speed of 3750 rpm
- Code K indicates a rated speed of 4000 rpm
- Code P indicates a rated speed of 5000 rpm
- Code Y indicates a rated speed of 6000 rpm
- Code U indicates a rated speed of 7000 rpm
- Code V indicates a rated speed of 8000 rpm
Power Output
Like torque, motors in MP Low inertia series have higher power density as well. Rated output (in kW) at respective rated speed can go up to 18.6kW (e.g., motor catalog number MPL-B980D) starting from a small figure of 0.16kW (e.g., motor catalog number MPL-A1510V).
Environmental Specifications
Rockwell Automation has made low inertia servo motors of the MPL series compatible with IP50 or IP66 depending upon the absence or presence of a shaft seal. If there is no shaft seal then the motor follows the IP50 standard minimum (typically IP50 if the shaft is mounted in an upward direction, IP51 if the shaft is installed in a horizontal direction, and IP53 if the shaft is installed in a downward direction). If there is a shaft seal (optional) then the IP66 standard is mandatory (so concerned equipment becomes dust and drip-free). Furthermore, the manufacturer binds its users to use those cable connectors which are environmentally sealed.
As far as the operating temperature is concerned, these servo motors are recommended to be used in the locality where the temperature ranges between 0 and 40 degrees centigrade. Anyhow, storage temperature can range between -30 and 70 degrees centigrade. If the temperature doesn’t remain within prescribed limits, then the owner must make arrangements for enough clearance, airflow, and heatsink.
While storing it must be ensured that the atmosphere is noncorrosive. Relative humidity at the storage site could be anywhere between 5 and 95% noncondensing.
Thermal Management
MPL series servo motors are designed to be smaller in size which complicates the heat management system. But advanced winding techniques, winding insulation, and winding material make this motor thermally efficient. Moreover, the presence of magnets instead of another winding also makes these motors more efficient thermally. During the designing process, heat transfer is also paid heed to. Anyhow, the manufacturer suggests not enclosing the motor except in situations when a forced-air mechanism is used to cool down the motor. It is also suggested that no such devices are placed near motors that produce heat. Aluminum heatsinks can also be used to dissipate heat more efficiently.
Certifications
MP Low inertia servo motors are components that are UL Recognized to corresponding CSA and UL standards. These servo motors are also CE marked for all applicable directives.
Other Products of the MP Series
Low inertia motors are regarded as one product of the MP series, as there are two more products of the MP series as well. These are MP series food-grade motors and stainless-steel motors. These two types of products are designed to meet some extra application requirements.
MP series food grade motors mainly possess characteristics of MP Low inertia motors but they also meet additional requirements of food and beverage related applications e.g. packaging. These motors are designed to have better sealing and food-grade coatings so they could be used near food items. Similarly, MP series stainless steel motors are designed to work in hygienic environments. These motors can be used safely in dairy and poultry-related applications where there could be a corrosive atmosphere or high pressure. These motors are ensured to be leakproof and they are factory sealed to achieve this purpose.