We specialize in Stepper Motors as well as unique DC & AC Electric Motors and Components found in the Industrial Electronic Industry. From air pumps to wall clocks; an AC, DC or Stepper Motor probably drives it. With AC Motors, you have Induction and Synchronous types. Synchronous are AC Motors designed to run at a constant speed up to the torque break point. AC synchronous motors are called “Line Locked” which means they rotate at a speed that is a multiple of the power line frequency. US power is 60 Hz (Hertz,) so a 3600RPM synchronous AC Motor at 60Hz, would run at 3000 RPM at 50Hz. This is the basic premise of Variable Frequency AC Motor Drives found in machine tools. Synchronous AC Motors are used in clocks, Power factor correction and other RPM critical applications. Induction AC Motors are the most common and cheapest of the consumer motors. Induction AC Motors are used in vacuum cleaners, Fans and pumps, etc. These AC Motors are loosely line locked but are designed to run at non synchronous speeds and torques. AC Motors are less sensitive to input voltage and at no load will run at near rated RPM over a large voltage range. What is lost is torque.
DC Motors are generally used in lower voltage applications where portability is the primary goal. Most DC Motors have brushes to switch the magnetic alignment to cause rotation. DC Motors operate over a wide range of voltages. A 12V DC Motor will operate down below 6V or up to over 15 or more. A 12V, 1200rpm DC Motor at no load will drop to near ˝ Speed at 6V but torque will be lower. The way to lower a DC Motor speed is through the use of Pulse Width Modulation (PWM).
Stepper Motors are a brushless DC Motor more like Synchronous AC motors. For more information, please read How does a Stepper Motor Work. Applying a DC voltage to a Step motor will not cause it to rotate. In a Stepper Motor both the Stator and the Rotor have “Teeth” but not equal in number. The teeth form poles of the magnetic field. The rotor is constructed of multi pole magnets while the Stator is made of coils around shaped steel laminations. When a current is applied to a coil; the field causes a set of stator & rotor teeth to align and the shaft moves. Another pulse to the same coil does not produce anything as the poles are already aligned. We now have 1 coil set & 1 Magnet set aligned, but another set is now misaligned. By pulsing a second coil the rotor will move into alignment with the next set of poles. So by pulsing first coil then second then back to first etc, then the rotor will rotate. Most Step motors are listed by NEMA Frame size. This is the measurement of one side of the square mounting face in inches. A size 17 is approximately 1.7in. on a side.
Electric Motors and Components
We specialize in Stepper Motors as well as unique DC & AC Electric Motors and Components found in the Industrial Electronic Industry.
Electric Motors and Components, AC Motors, DC Motors |
