In general, electric motors have two characteristics. They are dependable and they are dumb. The dependability shows itself in the way that the proper motor, correctly installed, will give years of faithful service, doing the job it has been asked to do: turn, turn, turn – outputting a specific amount of force, measured in horsepower or kilowatts.
The dumb part is that the motor will only do that – unless you tell it to do something else. That is the easy part of the electric motor story. The hard part is all the something elses you can tell it to do.
Jim Ryan, IBT’s electrical product specialist for motors and drives, is generally given to humor as he goes about his day-to-day duties. But, he does not joke much when you get him started on the whole question of motors (the dumb part) and drives (the smart part). He is serious because he realizes that this is a very complex situation. And, as in many complex situations, making wise choices can make a major difference in the outcome.
On the one hand, a motor is a motor is a motor. On the other hand, all motors are not created equal. Not only are they different in terms of output, they are different in terms of construction, materials, current requirements, protection, efficiency, output interface and performance profiles. And, they are different in terms of what you can expect them to do when you put them to work.
Motors need to be started, which may be accomplished by a variety of means. The output torque may need to be monitored and controlled, so that neither too little nor too much force is supplied to the work. Speed may have to be varied through a cycle. In the case of servo motors, and step motors, they may need to be started and stopped on command.
With the technical developments of the past ten years, motor drives and control devices have gotten smarter and smarter. With the application of microprocessors and their capacity to be programmed with complex instructions, drives help motors work smarter and more precisely than ever. Drives can be programmed through key pads, downloaded from PCs and other computers, and also be directed through operator interface.
IBT represents a number of vendors who manufacture a full range of motors and drives, allowing the company to supply a near infinite variety of combinations to fit customer needs.
Ryan’s explanation of how motors and controls fit into the picture is an interesting one.
There is work to be done. Gears or belts need to be driven, something needs to be moved. There is energy to be applied. In today’s world, most of the energy comes to us in the form of electricity. So, if we look at the world as a flow, downstream is the work. Upstream is the electricity. And, right in the middle is the motor and its controls. How we put them together and tell them what to do is extremely important in getting the job done in a factory or just about any place else.
Considering the motor and its control devices as a unit makes sense because the control unit has the smarts to tell the dumb motor how to behave.
As in any complicated application, there is usually an easy answer, an OK answer and a right answer.
Getting to the right answer shouldn’t be a matter of luck. It should be based on experience, knowledge and information. Getting to the right answer starts with asking the best questions. The first question should be the broad one: What is it that we are trying to do here? Probably the next several questions have to do with clarifying and verifying the answer to the first question.
For example, not long ago a customer ordered a motor for a pump. Since the caller had a specification in mind, one response would be to pull the motor off the shelf and send it his way. That would be dangerously simple for dedicated and curious people like Jim Ryan and his IBT crew.
Jim got interested in the application and started getting a better picture of just what was involved with the process. What he found, as he and his IBT co-workers pursued the situation, is very interesting. Jim explains: The motor the customer wanted would have driven the pump he had, more or less. But, he didn’t have one pump, he had two – moving different fluids – that filled the tank. And, he needed to drain the tank at times as well.
The way the customer was doing it was to use one motor for three tasks. And he was doing all the work (hooking up pumps turning motors on and off) by hand. The work got done, of course, but it was a relatively messy arrangement.
In addition, the situations of when the different pumps needed to be operated was predictable – based on cycles and fluid levels. So, the guy wanted a motor – but what we ended up recommending to them was a system to handle all the work without having to fool with it all the time. They bought it and they love it.
With the Federal Governments EPAct standards covering motor efficiency, plants have a major opportunity to look into their current electric motor installations and seek ways to improve the efficiency. Because electric motors are such a major consumer of energy, the mandate has been to greatly improve the motor’s efficiencies. Its working
New motors will draw less current than older models while still delivering high performance. The savings in energy are calculated to show payback for the efficient motor over a small portion of the new motors useful life. And, all manufacturers benefit from the lowering of energy consumption, in lower costs and fewer availability problems.
Ryan has key co-workers at IBT headquarters who are available to help branches and customers with problems. Contact IBT with any questions.