Q.1 A

Q.1 B

Q.1 C

Working Principle Of A DC MotorA motor is an electrical machine which converts electrical energy into mechanical energy. The principle of working of a DC motor is that "whenever a current carrying conductor is placed in a magnetic field, it experiences a mechanical force". The direction of this force is given by Fleming's left hand rule and it's magnitude is given by F = BIL. Where, B = magnetic flux density, I = current and L = length of the conductor within the magnetic field.Fleming's left hand rule: If we stretch the first finger, second finger and thumb of our left hand to be perpendicular to each other AND direction of magnetic field is represented by the first finger, direction of the current is represented by second finger then the thumb represents the direction of the force experienced by the current carrying conductor

When armature windingsare connected to a DC supply, current sets up in the winding. Magnetic field may be provided by field winding (electromagnetism) or by using permanent magnets. In this case, current carrying armature conductors experience force due to the magnetic field, according to the principle stated above.

Commutator is made segmented to achieve unidirectional torque. Otherwise, the direction of force would have reversed every time when the direction of movement of conductor is reversed the magnetic field.

Q.1D

An autonomous robot is a robot that performs behaviors or tasks with a high degree of autonomy, which is particularly desirable in fields such as space exploration, household maintenance (such as cleaning), waste water treatment and delivering goods and services.

Some modern factory robots are "autonomous" within the strict confines of their direct environment. It may not be that every degree of freedom exists in their surrounding environment, but the factory robot's workplace is challenging and can often contain chaotic, unpredicted variables. The exact orientation and position of the next object of work and (in the more advanced factories) even the type of object and the required task must be determined. This can vary unpredictably (at least from the robot's point of view).

One important area of robotics research is to enable the robot to cope with its environment whether this be on land, underwater, in the air, underground, or in space.

A fully autonomous robot can:

Gain information about the environment Work for an extended period without human intervention Move either all or part of itself throughout its operating environment without human assistance Avoid situations that are harmful to people, property, or itself unless those are part of its design specificationsQ.1E Comb-drives are capacitive actuators, often used as linear actuators that utilize electrostatic forces that act between two electrically conductive combs. Comb drive actuators typically operate at the micro- or nanometer scale and are generally manufactured by bulk micromachining or surface micromachining a silicon wafer substrate.The attractive electrostatic forces are created when a voltage is applied between the static and moving combs causing them to be drawn together. The force developed by the actuator is proportional to the change in capacitance between the two combs, increasing with driving voltage, the number of comb teeth, and the gap between the teeth. The combs are arranged so that they never touch (because then there would be no voltage difference). Typically the teeth are arranged so that they can slide past one another until each tooth occupies the slot in the opposite comb.Restoring springs, levers, and crankshafts can be added if the motor's linear operation is to be converted to rotation or other motions.The force can be derived by first starting with the energy stored in a capacitor and then differentiating in the direction of the force. The energy in a capacitor is given by:

Using the capacitance for a parallel plate capacitor, the force is:

Q.1 F

There are two ways of transmitting a byte between two digital devices. We can either transmit the byte in PARALLEL or we can transmit the byte in SERIAL form. The drawing to the left illustrates the differences between these two types of communication mechanisms. In parallel mode, each bit has a single wire devoted to it and all the bits are transmitted at the same time. In serial mode, the bits are transmitted as a series of pulses.

Q.3A

The Speed of Induction Motor is changed from Both Stator and Rotor SideThe speed control of three phase induction motor from stator side are further classified as :

1. V / f control or frequency control.2. Changing the number of stator poles.3. Controlling supply voltage.4. Adding rheostat in the stator circuit.

The speed controls of three phase induction motor from rotor side are further classified as: 1. Adding external resistance on rotor side.2. Cascade control method.3. Injecting slip frequency emf into rotor side.

Q.3B Relief Valve

Always use a relief valve with fixed-displacement hydraulic pumps. Pressure-compensated pump circuits also may use a relief valve for certain applications.

Think of a relief valve in a hydraulic system as a fuse or circuit breaker in an electric circuit. An electric circuit never blows a fuse unless it overloads. When an electric circuit overloads, it is inoperable until reset. Usually the person responsible for resetting the fuse looks for the reason it blew and fixes the problem before restarting the machine. Many hydraulic circuits allow the relief valve to dump some or all pump flow to tank all or part of the time. The extra power to produce that unused flow is expensive. Also, heat generation from excess flow requires larger heat exchangers that are expensive to buy and operate.

Protecting the pump and the system from excess pressure is the only valid function for a relief valve. At no time should the relief valve be used to pass excess pressure fluid to tank. When excess pump flow goes to tank, it generates heat. The relief valve in a well-designed hydraulic circuit never relieves oil to tank — unless there is a circuit or control malfunction.

Q.5A Scada

SCADA (supervisory control and data acquisition) is a system that operates with coded signals over communication

channels so as to provide control of remote equipment (using typically one communication channel per remote station).

The control system may be combined with a data acquisition system by adding the use of coded signals over

communication channels to acquire information about the status of the remote equipment for display or for recording

functions.[1] It is a type of industrial control system (ICS). Industrial control systems are computer-based systems that

monitor and control industrial processes that exist in the physical world. SCADA systems historically distinguish

themselves from other ICS systems by being large-scale processes that can include multiple sites, and large distances.[2] These processes include industrial, infrastructure, and facility-based processes.

Common system components[edit]

A SCADA system usually consists of the following subsystems:

Remote terminal units (RTUs) connect to sensors in the process and convert sensor signals to digital data. They

have telemetry hardware capable of sending digital data to the supervisory system, as well as receiving digital

commands from the supervisory system. RTUs often have embedded control capabilities such as ladder logic in

order to accomplish boolean logic operations.

Programmable logic controller (PLCs) connect to sensors in the process and convert sensor signals to digital

data. PLCs have more sophisticated embedded control capabilities (typically one or more IEC 61131-

3 programming languages) than RTUs. PLCs do not have telemetry hardware, although this functionality is

typically installed alongside them. PLCs are sometimes used in place of RTUs as field devices because they are

more economical, versatile, flexible, and configurable.

A telemetry system is typically used to connect PLCs and RTUs with control centers, data warehouses, and the

enterprise. Examples of wired telemetry media used in SCADA systems include leased telephone lines and WAN

circuits. Examples of wireless telemetry media used in SCADA systems include satellite (VSAT), licensed and

unlicensed radio, cellular and microwave.

A data acquisition server is a software service which uses industrial protocols to connect software services, via

telemetry, with field devices such as RTUs and PLCs. It allows clients to access data from these field devices

using standard protocols.

A human–machine interface or HMI is the apparatus or device which presents processed data to a human

operator, and through this, the human operator monitors and interacts with the process. The HMI is a client that

requests data from a data acquisition server.

A Historian is a software service which accumulates time-stamped data, boolean events, and boolean alarms in a

database which can be queried or used to populate graphic trends in the HMI. The historian is a client that

requests data from a data acquisition server.

A supervisory (computer) system, gathering (acquiring) data on the process and sending commands (control) to

the SCADA system.

Communication infrastructure connecting the supervisory system to the remote terminal units.

Various processes and analytical instrumentation.

Q.4A UART

A universal asynchronous receiver/transmitter is a computer hardware device that translates data

between parallel and serial forms. UARTs are commonly used in conjunction with communication standards such

as TIA (formerly EIA) RS-232, RS-422 or RS-485. The universal designation indicates that the data format and

transmission speeds are configurable. The electric signaling levels and methods (such as differential signaling etc.) are

handled by a driver circuit external to the UART.

A UART is usually an individual (or part of an) integrated circuit (IC) used for serial communications over a computer or

peripheral device serial port. UARTs are now commonly included in microcontrollers.

A universal asynchronous receiver/transmitter, abbreviated UART is a computer hardware device that translates data

between parallel and serial forms. UARTs are commonly used in conjunction with communication standards such

as TIA (formerly EIA) RS-232, RS-422 or RS-485. The universal designation indicates that the data format and

transmission speeds are configurable. The electric signaling levels and methods (such as differential signaling etc.) are

handled by a driver circuit external to the UART.

A UART is usually an individual (or part of an) integrated circuit (IC) used for serial communications over a computer or

peripheral device serial port. UARTs are now commonly included in microcontrollers.

Q.4 B FRLAir leaving a compressor is hot, dirty, and wet—which can damage and shorten the life of downstream equipment, such as valves and cylinders. Before air can be used it needs to be filtered, regulated and lubricated.An air line filter cleans compressed air. It strains the air and traps solid particles (dust, dirt, rust) and separates liquids (water, oil) entrained in the compressed air. Filters are installed in the air line upstream of regulators, lubricators, directional control valves, and air driven devices such as cylinders and air motors.

Air line filters remove contaminants from pneumatic systems, preventing damage to equipment and reducing production losses due to contaminant related downtime. Downtime in an industrial plant is expensive; often it is the result of a contaminated and poorly maintained compressed air system.Selecting the proper size of filter for any application should be done by determining the maximum allowable pressure drop, which can be caused by the filter. The pressure drop can be determined by referring to flow curves provided by the manufacturer.

There are three types of filters. General purpose, Coalescing (oil removal), and Vapor removal. General Purpose are used to remove water and particles, Coalescing to remove oil and Vapor removal to remove oil vapor and odor.Pressure regulators reduce and control fluid pressure in compressed air systems. Regulators are also frequently referred to as PRVs (pressure reducing valves). Optimally, a pressure regulator maintains a constant output pressure regardless of variations in the input pressure and downstream flow requirements. In practice, output pressure is influenced to some degree by variations in primary pressure and flow.

Q.4C How Does A Stepper Motor Work?

The unique feature of a stepper motor is that the shaft rotates in definite steps, one step being taken each time a command pulse is received. When a definite number of pulses are supplied, the shaft rotates through a definite known angle. The rotor of a stepper motor is gear shaped and it can be of ferromagnetic material or permanent magnet. Multiple toothed poles on which field coils are wound are arranged around the gear shaped rotor. The stator poles are magnetised in the appropriate manner by using a microcontroller or microprocessor or by other means.First, one pole is magnetised by supplying the corresponding field coil. This toothed pole then aligns the rotor teeth due to magnetic attraction. Rotor teeth are slightly offset from the next pole.At the next step, first pole is demagnetised and the second is magnetised. This causes the rotor to rotate in a fixed angle to align with the second pole and offset with the previous pole.This was the basic working principle of a stepper motor. The rotor can be made multiple stacked to achieve more steps. Also, different types of stepping (like full step, half step or micro step) can be used for achieving more steps.

Basic Classification of Stepper MotorsBased on the type of construction stepper motors can be classified as,

Variable Reluctance (VR) stepper motor Permanent Magnet (PM) stepper motor Hybrid stepper motor

Variable Reluctance (VR) stepper motorThe variable reluctance stepper motors are those which have a rotor made of ferromagnetic substances. Hence when the sator is excited it becomes an electromagnet and the rotor feels a pull in that direction. The ferromagnetic substance always tries to align itself in the minimum reluctance path.By exciting the coils, a magnetic field is procured and airgap reluctance is varied. Hence it is called a variable reluctance stepper motor. In this motor, the direction of the motor is independent of the direction of the current flow in the windings.Permanent Magnet (PM) stepper motorHere the rotor is permanently magnetized. Hence, the movement of the motor is due to the attraction and repulsion between the stator and rotor magnetic poles.In this motor, the direction of the motor is directly dependent of the direction of the current flow in the windings as the magnetic poles are reversed my changing the direction of the current flowing through the rotor.Hybrid stepper motorThe hybrid stepper motor, as the name suggest is a motor designed to provide better efficiency by combining the pros of both the permanent magnet stepper motor and variable reluctance stepper motor.The VR and PM stepper motors are the most common type of stepper motors. The only difference is that, in the variable reluctance stepper motor, the rotor is made of a ferromagnetic substance and in the case of permanent magnet stepper motor, the rotor is permanently magnetized.