Types of Variable Frequency Drives

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There are 3 general types of variable frequency drives:

  • Eddy Current Drives
  • DC Drives
  • AC Drives

Each type of variable frequency drive can be divided into different variations. Every variable frequency drive system operates an electric motor and a speed control unit. Variable frequency drive technology in today’s manufacturing processes mainly consist of solid state electronic components in a single control system. Older variable frequency drive systems use mechanical moving parts that in short periods of time, result in equipment failure due to worn parts from constant motion.

DC Motor Drives

Types of Variable Frequency DrivesDC motors have a rotating armature winding (winding in which a voltage is induced) but non-rotating armature magnetic field and a static field winding (winding that produce the main magnetic flux) or permanent magnet. Different connections of the field and armature winding provide different inherent speed/torque regulation characteristics. The speed of a DC motor can be controlled by changing the voltage applied to the armature or by changing the field current. The introduction of variable resistance in the armature circuit or field circuit allowed speed control. Modern DC motors are often controlled bypower electronicssystems called DC drives.

DC drives are also known as DC Motor Speed Control Systems.The speed of a DC motor is directly proportional to armature voltage and inversely proportional to motor flux; either armature voltage or field current can be used to control the motor speed. DC Motors have become expensive and today most DC motor speed control systems are retrofitted with an AC induction motor and AC variable speed drive. AC variable frequency drives are less expensive than DC Drive systems, are more available and are more energy efficient than DC Drive systems.

Eddy Current Motor Drives

Types of Variable Frequency DrivesAn eddy currentdrive consists of a fixed speed motor and an eddy current clutch. The clutch contains a fixed speed rotor and an variable speed rotor separated by a small air gap. A direct current in a field coil produces a magnetic field that determines thetorquetransmitted from the input to the output rotor. The controller provides closed loop speed regulation by varying the clutch current, allowing the clutch to transmit enough torque to operate at the desired speed. Speed feedback is provided by an integral AC tachometer.

Eddy current drives are less efficient than all other types of variable frequency drives.Nearly all eddy current motor drive systems are obsolete today. Eddy Current motor drives were designed and manufactured decades ago and there are very few manufacturing facilities across the globe that still use them in production. When an Eddy Current motor drive system fails, it’s usually too expensive to repair and impossible to replace. When an Eddy Current motor drive reaches the end of its life cycle and can no longer be repaired, manufacturers retrofit the Eddy Current Drive system with an AC Induction Motor and an AC Variable Frequency Drive system.

AC Motor Drives

Types of Variable Frequency DrivesAC variable frequency drives are also known as, VSDs (variable speed drives), inverters, AFDs (adjustable speed drives), and micro drives. AC variable frequency drives are used in many applications such as AC Servo Systems, Air Compressors, Conveyor Systems, Lathes, Mills, Food Processing production lines, Waste Water treatment systems, Submersible Pumps, HVAC fans and blowers, and many more applications in the industrial manufacturing world.

Approximately one third of the world’s electrical energy is supplied by electric motors in fixed-speed centrifugal pump, fan, and air compressor applications. This proves thatsignificant energy efficiency improvement opportunities are available in the industrial manufacturing world if older DC motor speed control systems and eddy current drive systems are retrofitted with AC variable frequency drive systems.Most industrial manufacturers replace their eddy current and DC variable frequency drive systems with AC variable frequency drive systems. Today, technology has reduced AC variable frequency drive systems’ cost, physical size, and has improved performance through advances in semiconductor switching devices, simulation, control techniques, and control hardware and software.

Manufacturers across the globe capitalize on AC variable frequency drive technology to save money on their utility bills, increase quality control, decrease production downtime, and improve overall efficiency on production lines.

 

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What is a Variable Speed Drive?

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What is a Variable Speed Drive?Variable speed drives are also known as variable frequency drives, VFD’s, adjustable speed drives, and inverters. Variable speed drives are solid state motor control systems used mainly for industrial manufacturing. Variable speed drives are designed to control the speed of an electric motor. Variable speed drives can reduce energy costs up to 50% by speed reduction on applications where the full speed (RPM) of the electric motor is not required.

The energy saved on a utility bill from using a variable speed drive is often significant enough to pay for the variable speed drive within a couple of months from installation date. Variable speed drives are commonly used on pump, fan, and air compressor applications, and are often used in manufacturing facilities to increase or decrease the start up time on alternating current (AC) electric motors.

Increasing and/or decreasing the start up time on an AC current electric motor via a variable speed drive can add years to the motor’s overall lifespan. Using a variable speed drive can also improve efficiency on production demands. Variable speed drives provide the ability to control the frequency of starting and stopping an AC electric motor.This ability provides a means by which an AC electric motor is only operating when needed. AC electric motors have a longer lifespan if they are not continuously operating when they do not need to be.

Types of Variable Speed Drives

What is a Variable Speed Drive?The most common type of variable speed drive is known as a V/Hz (volts per hertz), and are applied to applications such as fans, pumps, air compressors, and other related applications wherehigh starting torque is not required. V/Hz variable speed drive applications typically do not require full torque when the AC motor is operating at less than the base speed (RPM) of the electric motor. V/Hz variable speed drives are the most inexpensive type of variable speed drive. V/Hz variable speed drives do not provide full motor torque at low RPM.

Open-Loop vector drives are also known as s”ensorless vector” variable speed drives. Open loop vector drives adapted the name “sensorless vector” because they do not use an external encoder for speed feedback to the motor.Open loop vector drives are used in applications where high starting torque and full torque at low speed (RPM) is required. Open-Loop vector drives operating a motor a zero RPM should not be used on crane or hoist applications. Most open-loop vector drives are used on CNC machines, mixers, mills, lathes, and other applications where high starting torque or full torque at low RPM is needed.Open loop vector drives are usually more expensive than a V/Hz variable speed drives.

Closed-Loop vector drives are used in applications where precise speed control (0.01%) is needed, or in applications where extensive programming is needed. Closed-Loop vector drives use an encoder on the motor to provide constant shaft position indication to the drive’s microprocessor. The encoder feedback allows the drive microprocessor to constantly control torque no matter how many RPM the motor is operating at. Closed-Loop vector drives are used to provide the motor to operate at full torque even at zero RPM. Closed-Loop vector drives are commonly used on hoist and crane applications because crane and hoist motors must produce full torque prior to it’s brake being released, or the load will drop and it will not be able to stop.

 

Variable Frequency Drive Basics

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Variable frequency drives are also known as (VFDs), variable speed drives (VSDs), adjustable speed drives, and inverters. Variable frequency drives are solid state controllers used in AC or DC electric motor applications. Most variable frequency drives are applied on alternating current (AC) electric motors in the industrial manufacturing world. There are some direct current (DC) electric motor applications that apply variable frequency drives, but most manufacturers seek AC motors because DC motors are expensive and often fail. Variable frequency drives can also be used as a phase converters when three phase motors need to be operated from single phase power.

Variable frequency drives can be used in small appliances, large mills, lathes, air compressors, conveyors, and many other electric motor applications in the industrial manufacturing world. Over 30 percent of the world’s electrical energy is consumed by electric motors in fixed-speed fan, pump, and air compressor applications. The basic idea for using a variable frequency drive on mills, air compressors, and fans is to reduce the amount of electrical energy being consumed which consequently reduces electricity costs on unused power.

Energy Savings

About 3% of the total installed AC electric motors in the United States use variable frequency drives.An estimated 60-65% of electrical energy in the United States is used to supply electric motors, and 75% of that electrical energy is consumed by fan, pump and air compressor applications.

Approximately 18% of the electrical energy used in the 40 million motors in the United States could save power consumption via efficient energy improvement by using variable frequency drives on these electric motor applications.

Performance and Operation

Variable frequency drives are applied to alternating current (AC) electric motors to increase quality control in manufacturing processes in the industrial manufacturing world. Variable frequency drives increase quality control in the industrial manufacturing world via monitoring the electric motors’ speed, pressure, temperature, torque, and tension.

Fixed-speed electric motor loads subject the electric motor to a high starting torque and electrical current surges that are up to eight times the full-load motor current. When a variable frequency drive is used on an electric motor, the variable frequency drive gradually ramps the electric motor up to full load operating speed, and this decreases mechanical and electrical stress, which minimizes motor maintenance and motor repair costs which ultimately, extends the life of the electric motor and manufacturing equipment.

Variable frequency drives’ unique programming capabilities allow for application specific patterns to minimize electrical and mechanical stress on the electric motors’ they’re operating. Every variable frequency drive manufacturer uses a unique parameter selection designed so that every manufacturing facility can seek out the product designed for their industry.

Repair and Replacement

The internet has brought high demand of quality repair processes and competitive pricing in the industrial manufacturing world.Maintenance technicians began seeking alternative solutions via the internet for their need of variable frequency drive repair and replacement because maintenance technicians do not always receive the services needed to be a leader in their industry.

A highly trained repair facility is the backbone of successful production. Precision Electric has been repairing industrial electronics, rewinding electric motors, and servicing all other industrial-related equipment since 1982. Customers on the coasts of the United States send Precision Electric repair work everyday such as variable frequency drives, servo motors, servo drives, encoders, printed circuit boards, electric motors, and all other related equipment.

Precision Electric offers free quotes for all repair work and has a reputation for keeping manufacturers’ downtime to an absolute minimum while increasing production processes for 30 years. Equipment repaired by Precision Electric is more reliable than brand new equipment purchased from the manufacturer, because Precision Electric uses the most advanced testing equipment and replaces generic components with the best components in the industry. Precision Electric offers an in-service warranty on all repair work completed. The Precision Electric in-service warranty begins the day repaired work is put into service and ends 12 months thereafter.

Types of Variable Speed Drives

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There are three general types of variable speed drives- DC Motor drives, Eddy Current Drives, and AC Motor drives.Each type of variable speed drive can be divided into different variations. Every variable speed drive system will include an electric motor and a speed control unit. Variable speed drive technology today mainly consists of solid state electronic components in a single system. Older variable speed drive systems used mechanical parts that over time, resulted in failure due to moving and worn parts.

DC Motor Drives

DC drives are also known as DC Motor Speed Control Systems.The speed of a DC motor is directly proportional to armature voltage and inversely proportional to motor flux; either armature voltage or field current can be used to control the motor speed. DC Motors have become expensive and today most dc motor speed control systems have been retrofitted with an AC motor and AC variable speed drive. AC variable speed drives are less expensive than DC systems, are more available and are more efficient than DC systems.

Eddy Current Motor Drives

An eddy currentdrive consists of a fixed speed motor and an eddy current clutch. The clutch contains a fixed speed rotor and an adjustable speed rotor separated by a small air gap. A direct current in a field coil produces a magnetic field that determines thetorquetransmitted from the input to the output rotor. The controller provides closed loop speed regulation by varying the clutch current, allowing the clutch to transmit enough torque to operate at the desired speed. Speed feedback is provided by an integral AC tachometer.

Eddy current drives are less efficient than other types of drives.Nearly all eddy current motor drive systems are obsolete today. There are few manufacturing facilities across the globe that still use eddy current motor drive systems, and when the equipment fails, it’s expensive to repair and often impossible to replace.

AC Motor Drives

AC variable speed drives are also known as, VSDs, variable frequency drives, VFDs, inverters, adjustable speed drives, and micro drives. AC variable frequency drives are used in many applications such as swimming pool pumps, air compressors, conveyor belts, lathes, mills, food processing production lines, waste water treatment pumps, HVAC fans and blowers, and many more applications in the industrial manufacturing world. Approximately one third of the world’s electrical energy is supplied by electric motors in fixed-speed centrifugal pump, fan, and air compressor applications. This proves thatsignificant energy efficiency improvement opportunities are available in the industrial manufacturing world if older DC motor speed control systems and eddy current drive systems are retrofitted with AC variable frequency drive systems.

Conclusion

Most manufacturers currently seek to replace their eddy current and DC variable speed drive systems with AC variable speed drive systems. Today, technology has reduced AC variable speed drive systems’ cost, physical size, and has improved performance through advances in semiconductor switching devices, simulation, control techniques, and control hardware and software. Manufacturers across the globe capitalize on AC variable speed drive technology to save money on their power bill, increase quality control, decrease production downtime, and improve overall efficiency in production lines.

 

What is a Variable Frequency Drive?

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Variable frequency drives (VFD) are also known as variable speed drives (VSD), and inverters. Variable frequency drives are solid state motor control systems used in manufacturing facilities across the globe. Variable frequency drives are designed to control the speed of an alternating current (AC) electric motor. Variable frequency drives can reduce energy costs up to 50% by speed reduction on applications where the full speed (RPM) of the electric motor is not required.

This energy savings is often significant enough to pay for the variable frequency drive within a couple of months. Variable frequency drives are commonly used on pump, fan, and air compressor applications, and are often used in manufacturing facilities to increase or decrease the start up time on alternating current (AC) motors.

Increasing and/or decreasing the start up time on an AC motor can add years to the overall lifespan of an AC motor, and can also improve efficiency on production demands. Variable frequency drives provide the ability to control the frequency of starting and stopping an AC motor.This ability provides a means by which an AC electric motor is only operating when needed. AC electric motors have a longer lifespan if they are not continuously operating when they do not need to be.

There are a few different types of variable frequency drives. The most common type of variable frequency drive is known as a V/Hz (volts per hertz), and are applied to applications such as fans, pumps, air compressors, and other related applications where high starting torque is not required. V/Hz variable frequency drive applications typically do not require full torque when the AC motor is operating at less than the base speed (RPM) of the electric motor.

Another type of variable frequency drive is known as a vector control. Vector control is used on variable frequency drives where high starting torque and full torque at low speed (RPM) is present. Vector control variable frequency drives are usually more expensive than a V/Hz drives.

There are other types of variable frequency drives that are more complex than V/Hz and vector control. These more complex variable frequency drives are typically used for precise speed regulation of an AC motor as well as complex programming to regulate starting and stopping of an AC motor.

Preventing Electrical Bearing Damage Caused by VFD’s

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FACT: Every motor controlled by a variable frequency drive (VFD) should have bearing protection.

WHY?: Variable frequency drives induce voltage to the electric motor’s shaft that discharges through the bearings. This voltage can cause severe pitting, excessive bearing noise and eventuallybearing failure (see picture below).

IT GETS WORSE: Not only the motor’s bearings are at risk but coupled equipment like gear boxes, encoders, brake motors, etc. are also at risk of damage.Installing a bearing protection ring on your electric motor will channel that shaft voltage away from your bearings andsafelyinto ground.

 

Electric Motor Bearing Failure

Pitting in a electric motor’s bearing cause by shaft voltage induced by a variable frequency drive

 

 

 

 

 

 

 

REMEMBER: Insulating bearing housings alone does not prevent shaft current from discharging through the electric motor’s bearings and coupled equipment.

SOLUTION: Precision Electric can help you protect your bearings. Its cheaper than you think and it stops you from paying frequent electric motor repair cost. For more information on pricing on bearing damage protection and general purpose and inverter duty electric motors,

Please call toll free: 877-625-2402.

We will do everything we can to minimize your down time and maximize yourproductivity.

MC Series Drives

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The AC Tech MC Series drive is built in rugged steel enclosures that are known to last many years in production. The 16 character LCD display on the MC Series drive keypad allows for easy set up and operation.

  • MC Series drive available from 1/4 through 150HP
  • MC Series drive Input voltages from 120V single phase (with voltage doubler) to 590VAC
  • MC Series drive available in NEMA Type 1, 12, 4 and 4X Enclosures

The MC Series drive has a constant horsepower and can be set up for simple applications to demanding applications that require PID set-point control and many other programming functions. The MC Series drive consists of the MC1000 and MC3000 models; most applications will use the MC Series drive MC1000 with a remote keypad to Start, Stop, up, down, forward/reverse, Program/Run, Auto/Manual and Enter buttons. For non-reversing applications that require independent switching of start and stop from local to remote and speed control from auto to manual, the MC Series Drive MC3000 series keypad replaces the forward/reverse button with Local/Remote.

 

 

SMV Drive

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We’ve Been Servicing the Industrial World Since 1983.

Minimize Your Downtime. Maximize Your Productivity.

Call Toll Free: 1.877.625.2402

The new Lenze-AC Tech SMVector range of inverter drives offer sophisticated auto-tuning, fast dynamic torque response with impressive low-speed operation all from a compact and simple to use package. Ingress protection to IP65 allows for use in outdoor applications and indoor environments where atmospheric moisture is present or low pressure water jets are used. The SMV range is designed for motor applications where dynamic speed and torque control is demanded, making the units ideal for conveyors, food production lines, packaging equipment plus fan & pump systems.

All SMV Series products offer the benefits of the EPM, a rugged memory chip that plugs directly into the drives fascia, cutting programming time to seconds.

An EPM programming module allows drive parameters to be instantly copied onto the chip, and once plugged in, the EPM ensures the drive is ready to run without being powered up. OEM manufacturers can speed-up production and suppliers can provide effective low-cost product support.

Key Benefits :

  • IP65 integrity providing rugged environmental capabilities
  • Flux Vector operation providing precise motor control
  • 150% overload for 60 secs (200% for 15 secs)
  • Compact size, saving panel space
  • Intuitive user interface for fast setup
  • Easy navigation parameter structure
  • On-board PID controller with energy saving Sleep Mode function
  • User terminals status on 1 display
  • Built in EMC filter (standard on 240V 1 only, optional on 400V/480V 3)
  • Optional mains isolator with lock off meets IEC 60947-3

Control I/O Features :

  • Negative or Positive logic.
  • Motorised Potentiometer.
  • Scalable 4-20mA and 0-10V Analogue Input (with wire Breakdetection)
  • Status relay output.
  • Optional remote mountable keypad

Motor Control Features :

  • Flying restart
  • Auxiliary ramp to stop.
  • UL approved motor thermal overload protection system
  • Motor brake controller
  • Dual Acceleration/Declaration rates
  • S ramps
  • DC Injection braking
  • Motor Flux Braking
  • Sequencer
  • 8 preset speeds

Call Precision Electric today for price and delivery time for any Lenze-AC Tech, or other related products. We also provide repair services for all industrial electrical equipment.

Ryan Chamberlin
Inside Sales, Customer Support
[email protected]
Call Toll Free: 1.877.625.2402

Source: http://www.lenze-actech.eu/Products/SMVector/Overview/tabid/2239/Default.aspx

Do I Need An Encoder Or Resolver?

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We’ve Been Servicing the Industrial World Since 1983.

Minimize Your Downtime. Maximize Your Productivity.

Call Toll Free: 1.877.625.2402

Choosing the correct encoder or resolver for your application may seem tedious, but is an important decision that needs to be carefully examined before these devices are going to be used in your plant. Encoders and resolvers often are used to sense motor shaft speed in machines and robots. Resolvers have been around longer, but encoders are more widely used in modern designs because of higher accuracy and superior digital communication interfaces.

Incremental rotary encoders work on either of three technologies: optical, magnetic or capacitive. Each technology has its drawbacks and advantages, and the right choice typically is determined by the application.

“Optical encoders can be found in office applications such as copiers, and in industrial applications such as automated guided vehicles,” says Cory Mahn, senior specials engineer at Dynapar “Magnetic encoders typically are needed in harsh conditions where optical encoders could show significant performance decrease. These applications can be overhead cranes, paper mills and steel mills.”

The vulnerable component in optical encoders is the glass disk, and various designs are available to provide protection. “Our Safety-Lock bearing design incorporates two mechanically interlocked bearings that have the maximum possible distance between them,” says Tony Udelhoven, sensors division director at Turck “This design helps protect the internal optical disk system from shock and vibration that would damage traditionally designed encoder bearings.”

Some applications are too rugged for optical encoders, and others have inherent strong magnetic fields that preclude use of magnetic encoders. “Our capacitive encoders are designed and built to meet the challenges of difficult applications as they dont have bearings or optics, and are well-suited for direct-drive applications,” notes Joanna Suresh, product manager for motor feedback and absolute encoders at Sick.

Bearing design is critical for optical encoders because the bearings are subject to contact and wear. Magnetic encoders eliminate bearings from their design, and can also offer higher performance.No matter the type of encoder selected for a particular application, it requires an interface to other components in the automation system. As with many automation components, digital interfaces provide high-speed two-way communications, enabling high-resolution outputs and diagnostics.Although resolvers are not as widely used as encoders, they can be a good fit in certain applications.

If you are not certain of which product you should use, contact Precision Electric. You can reach us by email or telephone. Send the specifications for your application to me at the email address shown below. If you have a resolver or encoder that you would like quoted for either repair or replacement, let me know.

Ryan Chamberlin
Inside Sales, Customer Support
[email protected]
Call Toll Free: 1.877.625.2402

Sources:
http://www.sickusa.com
www.turck.us
www.dynapar.com
http://www.controldesign.com/articles/2011/EncoderResolver1101.html

Allen Bradley Alternative

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We’ve Been Servicing the Industrial World Since 1983.

Minimize Your Downtime. Maximize Your Productivity.

Call Toll Free: 1.877.625.2402

Customers of Precision Electric who use Allen Bradley products typically get frustrated when they don’t get support or more frequently, have to sign an expensive contract to get support. Eventually these customers seek alternative products for their applications. Precision Electric recommends Parker/SSD drive solutions for customers looking for an alternative to Allen Bradley. We have been a systems integrator as well as certified repair facility for Parker/SSD products since 1996.

Parker offers a full range of drives from stepper, compact and high performance servo, AC variable speed, high current output DC to panel mounted drives. Parker industry leading drives include Sensorless, Vector and Microstepping options. Parker drives are suitable for speed, torque or position control and are available in power ranges from fractional to over 2,000 hp.

Drive product offerings from Parker:

  • Open loop V/Hz speed control for induction motors
  • Sensorless vector and closed loop flux vector control
  • Brushless AC and DC servo control
  • Programmable servo drives
  • Stepper and microstepper
  • Field bus and ethernet based motion bus
  • Packaged systems in NEMA enclosure panels

Parker power electronics are used in a wide variety of markets ranging from industrial to life sciences and are supported by a highly technical distribution network around the globe.

  • Thousands of standard drive configurations
  • Custom engineered drives designed to your OEM application
  • Global manufacturing and service with local application support

Parker drives products carry international industrial approvals, including UL, cUL and CE marking.

Parker drive/controllers support numerous industry-standard fieldbus protocols including:

  • CANOpen
  • Ethernet IP
  • Ethernet Powerlink
  • Ethercat
  • Profibus
  • Modbus and others

Products are available as standalone packages or PC-bus cards. Call or email for further information.

Ryan Chamberlin
Inside Sales, Customer Support
[email protected]
Call Toll Free: 1.877.625.2402

 

 

Variable speed drive energy savings

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We’ve Been Servicing the Industrial World Since 1983.

Minimize Your Downtime. Maximize Your Productivity.

Call Toll Free: 1.877.625.2402

The use of variable frequency drives on variable torque loads for the purpose of gaining energy savings is a common application. Variable frequency drives operate as load controls within applications that may accomplish up to 50% reduction in energy costs. In general, an electric motor will turn at a rate proportional to the frequency of the alternating current (AC) applied to it. The majority of Variable Frequency Drives in the market today contain electronic circuitry that converts a 60Hz Line power into direct current. The VFD converts this line power into a pulsed output voltage that duplicates varying alternating current to a desired frequency.

In our ever growing world of technology variable frequency drives have over the past decade allowed to become a cost efficient way to reduce energy costs and increase system efficiencies. Today manufacturers around the globe within a wide range of industries are finding more ways to apply variable frequency drives to their manufacturing equipment.

From past experience, smaller HP drives typically fail in eight years and are more often replaced rather than repaired. Larger HP drives last longer by virtue of repairs that often require replacement circuit boards and other components. After bearing the cost of two or three replacement boards in any one drive, the user often realizes that the drive should have been junked sooner.

For an even more in depth explanation of Variable Frequency Drives go to Wikipedia.

RyanChamberlin
Inside Sales, Customer Support
[email protected]

AC Tech mc series manual & Lenze smvector drive

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If you need any AC Tech variable frequency drive literature, everything you’re looking for can be found right here on our website. Simply click the Manuals tab in the top right corner of this page. The following AC Tech literature can be found here: on our website.

SMV Series
Sub Micro Series
MC Series
MCH Series

All of the literature that AC Tech has available on their website, is available on our website. Precision Electric also has digital documentation available for Lenze products, Baldor products, and other manufacturers’ literature whom we work with. If you need specific documentation and you cannot find it elsewhere, send me an email request.

Precision Electric service fliers, brochures, line cards and other related documentation is available here on our website via PDF. If you click the Capabilities tab in the top right corner of this page you will be able to download these files. If you do not find the information you need on our website, email me, and I’ll do my best to help.

RyanChamberlin
Inside Sales, Customer Support
[email protected]