Elements of Industrial Automation Week 04 Notes.pdf
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The document discusses analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), explaining their functions and types. It also covers various electric motors, including DC and AC motors, detailing their principles, types, and applications. Additionally, special-purpose motors such as stepper, brushless DC, hysteresis, reluctance, and universal motors are outlined.
Elements of Industrial Automation Week 04 Notes.pdf
- 1. Vidya Vikas Educational Trust (R), Vidya Vikas Polytechnic 27-128, Mysore - Bannur Road Alanahally,Alanahally Post, Mysuru, Karnataka 570028 Prepared by: Mr Thanmay J.S, H.O.D Mechanical Engineering VVETP, Mysore Page | 33 Theory and Practical for week 04 what is ADC and DAC ADC-AnalogtoDigitalConverter An electronic integrated circuit which transforms a signal from analog (continuous) form to digital(discrete) form is known as ADC. Analog signals are directly measurable quantities while digital signals only have two states (binary 0 and binary 1). The heart of data acquision system is ADC. The digital systems require discrete digital data. Purpose of Analog to Digital conversion: • Processors perform arithmetic operations on digital signals. • Signals in digital form are less susceptible to effects of noise. • ADC provides link between analog world (of transducers) and digital world (of data and signal processing). Following are the types of Analog to Digital Converter (ADC): ➨Counter type(simplest) ➨Successive Approximation ➨Flash ADC ➨Sigma Delta DAC-DigitaltoAnalogConverter To convert digital values to analog voltage DAC is used. It performs inverse operation of analog to digital converter. The same has been depicted in the fig-2. Analog output = (Digital Input/(2N -1) )* Reference Input There are two types of DACs: • Weighted Resistor • Resistive Divider Following specifications are considered for the design, development as well as selection of DAC (Digital to Analog Converter). ➨Resolution ➨Reference voltages ➨Settling Time ➨Linearity ➨Speed ➨Errors below shows the functional blocks of A/D and D/A converters. The A/D converter accepts an analog sample and produces an N bit digital word, where as D/A converter accepts N bit digital word and produces an analog sample. The output of D/A converter is fed to the S/H circuit and staircase waveform is obtained this staircase waveform is further given to low pass filter which produces smooth analog signal.
- 2. Vidya Vikas Educational Trust (R), Vidya Vikas Polytechnic 27-128, Mysore - Bannur Road Alanahally,Alanahally Post, Mysuru, Karnataka 570028 Prepared by: Mr Thanmay J.S, H.O.D Mechanical Engineering VVETP, Mysore Page | 34 Motors- DC motor, Synchronous motor, Servo motor, An electric motor is a device used to convert electricity into mechanical energy—opposite to an electric generator. They operate using principles of electromagnetism, which shows that a force is applied when an electric current is present in a magnetic field. This force creates a torque on a loop of wire present in the magnetic field, which causes the motor to spin and perform useful work. Types of Electric Motors The types of Electric motors are available in three main segments like AC motor, DC motor, & special purpose motors. DC Motors The types of dc motors mainly include Series, Shunt, and Compound wound & PMDC Motor. 1). DC Shunt Motor: DC shunt motor works on DC and the windings of this electric motor like the armature windings and field windings are linked in parallel which is known as a shunt. This kind of motor is also called as shunt wound DC motor, where the winding type is known as a shunt winding. 2). Separately Excited Motor: In separately excited motor, the connection of stator and rotor can be done using a different power supply. So that the motor can be controlled from the shunt and the armatures winding can be strengthened to generate flux. 3). DC Series Motor: In DC series motor, rotor windings are connected in series. The operation principle of this electric motor mainly depends on a simple electromagnetic law. This law states that whenever a magnetic field can be formed around conductor & interacts with an external field to generate the rotational motion. These motors are mainly used in starter motors which are used in elevators and cars. 4). PMDC Motor: The term PMDC stands for “Permanent Magnet DC motor”. It is one kind of DC motor which can be inbuilt with a permanent magnet to make the magnetic field necessary for the electric motor operation. 5). DC Compound Motor: Generally, DC compound motor is a hybrid component of DC series and shunt motors. In this type of motor, both the fields like series and shunt are present. In this type of electric motor, the stator and rotor can be connected to each other through a series & shunt windings compound. The series
- 3. Vidya Vikas Educational Trust (R), Vidya Vikas Polytechnic 27-128, Mysore - Bannur Road Alanahally,Alanahally Post, Mysuru, Karnataka 570028 Prepared by: Mr Thanmay J.S, H.O.D Mechanical Engineering VVETP, Mysore Page | 35 winding can be designed with few windings of wide copper wires, which gives a small resistance path. The shunt winding can be designed with multiple windings of copper wire to get the full i/p voltage. AC Motors The types of ac motors mainly include synchronous, asynchronous, induction motor. 1). Synchronous Motor: The working of the synchronous motor mainly depends on the 3-phase supply. The stator in the electric motor generates the field current which rotates in a stable speed based on the AC frequency. Rotor depends on the similar speed of the stator current. There is no air gap among the speed of stator current and rotor. When the rotation accuracy level is high, then these motors are applicable in automation, robotics, etc. 2). Induction Motor: The electric motor which runs asynchronous speed is known as induction motor, and an alternate name of this motor is the asynchronous motor. Induction motor mainly uses electromagnetic induction for changing the energy from electric to mechanical. Based on the rotor construction, these motors are classified into two types namely squirrel cage & phase wound. Special Purpose Motors 1). Stepper Motor: The stepper motor can be used to offer step angle revolution, as an alternative to stable revolution. We know that for any rotor, the whole revolution angle is 180degrees. However, in a stepper motor, the complete revolution angle can be separated in numerous steps like 10-degree X 18 steps. This means, in a total revolution cycle the rotor will go stepwise eighteen times, every time 10 degree. Stepper motors are applicable in plotters, circuit fabrication, process control tools, usual movement generators, etc. 2). Brushless DC Motors: The brushless DC motors were first developed for achieving superior performance within a lesser space than brushed DC motors. These motors are lesser when compared with AC models. A controller is embedded into the electric motor to facilitate the process within the lack of a commutator and a slip ring. 3). Hysteresis Motor: The operation of the hysteresis motor is extremely unique. The rotor of this motor can be induced hysteresis and eddy current to generate the required task. The motor working can depend on the construction, 1-phase supply otherwise 3-phase supply. These motors give a very smooth process with stable speed, similar to other synchronous motors. The noise level of this motor is quite small, due to this reason they are applicable in numerous complicated applications wherever the soundproof motor is used such as sound player, audio recorder, etc. 4). Reluctance Motor: Basically, reluctance motor is a 1-phase synchronous motor & this motor construction is quite same with induction motor like cage type. The rotor in the motor is like squirrel cage type & the stator of the motor include sets of windings such as auxiliary and main winding. The auxiliary winding is very useful at the beginning time of the motor. As they offer a level operation at a stable speed. These motors are commonly used in synchronization applications which include signal generators, recorders, etc. 5). Universal Motor: This is a special kind of motor and this motor works on single AC supply otherwise DC supply. Universal motors are series wound where the field and armature windings are connected in series and thus generates high starting torque. These motors are mainly designed for operating at high-speed above 3500 rpm. They utilize AC supply at low-speed and DC supply of similar voltage.