How to Select AC Motor Drives            Image Credit: ABB Drives and Motors; Eaton Corporation; Panasonic Electric Works     AC motor drives are defined as amplifiers or frequency inverters that interface between a controller and an AC motor. They convert step and direction input from the controller to currents and voltages compatible with the motor. These units are sometimes called variable frequency drives, referring to a...
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Q & A on AC Motor Drives

We asked our users for their input on AC Motor Drives. Here are the results of 337 users familiar with AC Motor Drives.

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice

Who Took Our Poll?Top

Design TrendsTop

Q:
What new technologies are influencing AC motor drive design?
49 answers
Answers:
The introduction of new power electronics componentry is a major factor in both the cost and packaging. An issue that needs attention is the patenting of drive technologies which limits innovative and competitive designs.
~Engineering, Design, Tomago, Australia
Modern user interfaces to make them easier and simpler to use, modern communication technologies (Ethernet etc.),... more SW functions embedded in drives.
~Design Engineer, Helsinki, Finland
I don"t get involved with a whole lot of the engineering of industrial applications, but I have noticed that the drives are getting smaller and the applications are everywhere.
~Dan W, Research & Development, Caldwell, ID
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Q:
From your perspective, which companies are creating the most innovative AC motor drives?
59 answers
Answers:
Allen Bradley, Eaton, Fuji, GE, Siemens, Omron
~Alexis Gonzalez, Mantenimiento Manager, Mexicali, Mexico
I have experience with Siemens, ABB and GE drives.
~Ivan Totev, Technical Support, Gzira, Malta
ABB, Hitachi delta for what i use and i know, Siemens is a good brand, but not so much used in my applications.
~Sebastiano L, Maintenance and repairing, Biella, Italy
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Applications and UseTop

Q:
What are some of the applications you have used an AC motor drive for?
87 answers
Answers:
I've used VFD's (Variable Frequency Drives) to control motors that run chip handling equipment for wood boilers and for automatic board handling decks for planer machines. I recently installed a 100 HP soft starter for a large bandsaw to limit excessive start-up current.
~Engineering, Consulting, Buckfield, ME
AC motor drives for pumping, high volume air flow, PCB eching, wave and reflow soldering, dc power source, braking (dc injection), HVAC, Stainless Steel fab, ice makers, drug manuf, tracking, computers, electric cars, ups, and grid tie's, rock crushing, conveyors, ...
~Engineering, Consulting, Lenexa, KS
1. The controlled mechanical load based on frequency converter - squirrel cage motor drive. Intended for modeling the load for different kinds of motors. 2. Study of squirrel cage motor control: scalar control, vector control, direct control of torque
~Armen Harutyunyan, Design Engineer, Yerevan, Armenia
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Q:
Please share with us any “non-standard” applications that an AC motor drive has been used for.
32 answers
Answers:
AC Drive as a Power Supply Unit. In India Frequency is 50HZ Standard. One motor required 60HZ as a standard power, hence we used drive as a power supply for giving 60 HZ. Voltage control through AC Drive in Glass company in vibrator application.
~Shashi Bhushan C, Sr Executive - Sales & Marketing, Ankleshwar, India
I have seen a drive installed on a coax cable line, controlling the jacketing machine with skip frequency being used to make different wrapping frequency loss.
~John F, 3rd Party Maintenance Technition, Staten Island, NY
Oil injected screw compressor to maintain process pressure variation within 0.1 bar and to control compressor machine devices.
~Taieb I, Production Engineer, Amman, Jordan
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Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of an AC motor drive?
19 answers
Answers:
Yes - improper selection - one installation with a 100 HP VFD driving a 4 pole motor on a variable torque centrifugal pump load - the user assumed he could extract 100 HP at 60% speed - since the unit was rated for 100 HP !!!!!
~Applied Products & Systems M, Technical Support, Oakville, Canada
Undersizing of constant torque applications (Could not get started). Improper sizing, application, and settings for a step up transformer on the output.
~Doug O, Engineer, Baton Rouge, LA
What I know of my experience is that incorrect usage of AC motor drives is going to burn AC motors and sometimes HV step up transformers.
~Ivan Totev, Technical Support, Gzira, Malta
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FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
39 answers
Answers:
The auto tuning based on neural system computing. Precious estimation of motor parameters for elimination of losses in energy save mode. In scalar mode the more points for approximation U/f curve. Take account of saturation. For simple applications like fans and so on - incorporated with motor drives: cheap and simple adjustable.
~Armen Harutyunyan, Design Engineer, Yerevan, Armenia
Input and Output Power Selectable, Input and Output Power Supply should be Universal. Input : 110 - 480 VAC [Single Phase to 3 Phase] Output : 230-480 VAC [3 Phase selectable]
~Shashi Bhushan C, Sr Executive - Sales & Marketing, Ankleshwar, India
Including an adaptive programming - or a function block program space within the drive adding more analog inputs for process control.
~Taieb I, Production Engineer, Amman, Jordan
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Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of an AC motor drive?
23 answers
Answers:
Please select AC Drive based on following details: Please Provide complete Motor details Please provide Application/ Process details. Existing Starting method and its load pattern
~Shashi Bhushan C, Sr Executive - Sales & Marketing, Ankleshwar, India
Location, distance, mounting method, power, weight, too much or too little torque or power or voltage. Compatibility with other components etc...
~John M, Design Engineer, Hamilton, Canada
Do select and dimension the drive based on the application needs, not always based on a motor ratings, because it can be over dimensioned.
~Design Engineer, Helsinki, Finland
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Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using AC motor drives?
29 answers
Answers:
Be sure you're comparing apples to apples. A module drive with several options vs. a complete drive including essential features (choke for harmonic mitigation, EMC filter, basic fieldbus comm. control panel) inside as standard. When taking into account the selection, installation and commissioning costs, quite often the module or lego style approach is more expensive.
~Design Engineer, Helsinki, Finland
Be sure to include the cost of programming the unit as part of the project cost if you do not have a PLC programmer in-house.
~Research & Development, Massillon, OH
Three most important when it comes to buying a drive and application: Correct sizing Choke for long distance cables Proper cooling system
~Khulekani D. Mthembu M, Technician, Secunda, South Africa
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