15-09-2016, 10:11 AM
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1. INTRODUCTION
An elevator (lift in British English) is a type of vertical transport equipment that efficiently moves people or goods between floors (levels, decks) of a building, vessel, or other structure. Elevators are generally powered by electric motors that either drive traction cables or counterweight systems like a hoist or pump hydraulic fluid to raise a cylindrical piston like a jack.
In agriculture and manufacturing, an elevator is any type of conveyor device used to lift materials in a continuous stream into bins or Silos, Several types exist, such as the chain and bucket, bucket elevator, grain auger screw conveyor using the principle of Archie’s screw, or the chain and paddles or forks of hay elevator.
Wheelchair access laws, elevators are often a legal requirement in new multistory buildings, especially where wheelchair ramps would be impractical.
Power can be generated by connecting the elevator arrangement and dc machine with help of belt or chain
DC machine acts as a generator which runs simultaneously with DC series motor. The power thus generated can be stored in the rechargeable battery. Power generation is indicated by LED. In this storage process we can use unidirectional current controller to avoid going back of power to the machine. This stored energy is DC that can be converted to AC with help of inverter. That AC is supplied to loads
3. DC SERIES MOTOR
3.1 INTRODUCTION
Direct current (D.C.) series motors get their name from the way their armature and field windings are connected together: in a series circuit
This type of connection gives a D.C. series motor the following characteristics:
High Starting Torque
No Load Operation
Poor Speed Regulation
They are widely used for starting heavy, industrial, high torque loads such as cranes, hoists, elevators, trolleys and conveyors, but are also used for automobile starters. The primary disadvantage of D.C. series motors is they cannot operate safely in an unloaded condition.
CONSTRUCTION
The basic components of a D.C. series motor are the armature, field windings, brush assembly, frame, endbells and bearings.
The armature is the rotating component of the motor and is made of a steel shaft with notched laminations that the armature windings are wound on. On one end of the shaft is the commutator, which consists of copper segments insulated from each other. A brush assembly holds the electrically conductive, carbon graphite brushes, which slide on the commutator segments and provide a means to connect the D.C. power supply to the rotating commutator. The commutator and brushes function as an electro-mechanical switch that changes the direction of current flow in the armature as it rotates. The field windings or magnet is a coil and laminated pole assembly powered by the same D.C power supply as the armature. To correct for armature reaction, interlopes are used to shift the neutral magnetic plane to eliminate brush arcing.
The motor frame is a circular, steel structure that mechanically supports the field poles. The end bells enclose all the components of the motor and are bolted onto the frame. Bearings are pressed into the end bells to provide free movement of the armature.
3.3 OPERATION
Motor action governs the operation of a D.C. series motor and states that a current-carrying coil will generate a magnetic field and if this coil is placed in another magnetic field, a force or torque will be exerted on the coil. This torque will be proportional to both the current in the coil and the strength of the magnetic field it is placed within.
The D.C. series motor’s armature (rotating component) is the previously mentioned current-carrying coil and the field winding (stationary component) of the motor is the other magnetic field. So, when the armature and field windings are energized by a D.C. power supply, current will flow through these windings and generate their respective magnetic fields and will be magnetically positioned in such a manner to cause torque. But this torque will only be sustained if the magnetic relationship of the armature and field are maintained. This is accomplished by the commutator, which switches the current flow and reverses the armature’s magnetic polarity every time the commutator segment passes through a brush, causing the armature to be attracted to the stationary field magnet, thus sustaining unidirectional torque or rotation.
3.4 CHARACTERISTICS
To understand the proper application of D.C. series motors, one must understand the characteristics of torque, speed and armature current relative to load changes. In D.C. series motors, the entire armature current (I armature) passes through the series field windings so the magnetic flux (Φ) produced is proportional to armature current:
Flux Φ α I armature
the torque produced will be proportional to the product of flux and armature current:
Torque α (Flux Φ) I armature
Since Flux Φ α I armature and Torque α (Flux Φ) I armature, it follows that the Torque will be proportional the square of I armature. In other words, in formula form:
Torque α I armature
this means that when a D.C. series motor is first started, very high torque will be produced because armature resistance is low, CEMF is zero and the total D.C. supply voltage will drive current through the armature. This armature current would be unimpeded, causing a very high torque. This characteristic makes D.C. series motors ideal for applications requiring high starting torque.
While torque is proportional to the square of the armature current, motor speed is inversely proportional to armature current.
Thus, the torque-speed characteristic of a D.C. series motor is:
Speed α 1/√T
this characteristic means that as the load on the motor increases, the armature current will increase and the torque will increase causing the motor speed to decrease. Hence, D.C. series motors have poor speed regulation because they are load dependent. It also means that as the load decreases, torque decreases and speed increases. At no load, the motor speed would ramp to an extremely high level that could ultimately destroy the motor. This runaway condition would prove to be a personal safety hazard as well.
Applications
D.C. series motors are ideal for large loads and industrial applications that require high starting torque. In addition, they have poor speed regulation that’s load dependent and exhibit an unstable runaway condition when unloaded. Hence, D.C. series motors should never be used where the loads are intermittent, change frequently, or frequently cycle on/off. For example, a water pump drive that runs constantly and requires only small adjustments to maintain the flow rate would be a good application for a series motor. Conversely, a pump those cycles frequently to maintain a tank water level wouldn’t.
4. DC GENERATOR
4.1 INTRODUCTION
An electrical Generator is a machine which converts mechanical energy (or power) into electrical energy (or power).
4.2 PRINCIPLE
It is based on the principle of production of dynamically or ( motionally) induced e.m.f (Electromotive Force). Whenever a conductor cuts magnetic flux, dynamically induced e.m.f. is produced in it according to Faraday’s Law’s of Electromagnetic Induction This e.m.f. causes a current to flow if the conductor circuit is closed.
Hence, the basic essential parts of an electric generator are:
A magnetic field and
A conductor or conductors which can so move as to cut the flux.
CONSTRUCTION
A single-turn rectangular copper coil abcd moving about its own axis in a magnetic field provided by either permanent magnets or electromagnets. The two ends of the coil are joined to two split-rings which are insulated from each other and from the central shaft. Two collecting brushes (of carbon or copper) press against the slip rings.
4.4 APPLICATIONS
• In series arc lightening this type of generators are mainly used
• It is used in railway service
5. LEAD-ACID BATTERY
5.1 INTRODUCTION
The lead-acid battery was invented in 1859 by French physicist Gaston planet and is the oldest type of rechargeable battery .despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents mean that the cells have a relative for use in motor vehicles to provide the high current required automobile starter motors.
As they are inexpensive compared to newer technologies, lead-acid batteries are widely used even when surge current is not important and other designs could provide high energy densities.
For the roles, modified version of the standard cell may be used to improve storage times and reduce maintenance requirements. Gel-cell and absorbed glass-mat batteries are common in these roles, collectively known as VRLA (valve-regulated lead-acid) batteries
5.2 RECHARGEBLE BATTERIES:
A rechargeable battery or storage battery is a group of one or more electrochemical cells. They are known as secondary cells because their electrochemical reactions are electrically reversible.
Rechargeable batteries come in many different shapes and sizes, ranging anything from a button cell to megawatt systems connected to stabilize an electrical distribution network. Several different combinations of chemicals are commonly used, including: lead-acid, nickel cadmium(NiCad), nickel metal hydride (Nigh), lithium ion (Li-ion), and lithium ion polymer (Li-ion polymer).
1. INTRODUCTION
An elevator (lift in British English) is a type of vertical transport equipment that efficiently moves people or goods between floors (levels, decks) of a building, vessel, or other structure. Elevators are generally powered by electric motors that either drive traction cables or counterweight systems like a hoist or pump hydraulic fluid to raise a cylindrical piston like a jack.
In agriculture and manufacturing, an elevator is any type of conveyor device used to lift materials in a continuous stream into bins or Silos, Several types exist, such as the chain and bucket, bucket elevator, grain auger screw conveyor using the principle of Archie’s screw, or the chain and paddles or forks of hay elevator.
Wheelchair access laws, elevators are often a legal requirement in new multistory buildings, especially where wheelchair ramps would be impractical.
Power can be generated by connecting the elevator arrangement and dc machine with help of belt or chain
DC machine acts as a generator which runs simultaneously with DC series motor. The power thus generated can be stored in the rechargeable battery. Power generation is indicated by LED. In this storage process we can use unidirectional current controller to avoid going back of power to the machine. This stored energy is DC that can be converted to AC with help of inverter. That AC is supplied to loads
3. DC SERIES MOTOR
3.1 INTRODUCTION
Direct current (D.C.) series motors get their name from the way their armature and field windings are connected together: in a series circuit
This type of connection gives a D.C. series motor the following characteristics:
High Starting Torque
No Load Operation
Poor Speed Regulation
They are widely used for starting heavy, industrial, high torque loads such as cranes, hoists, elevators, trolleys and conveyors, but are also used for automobile starters. The primary disadvantage of D.C. series motors is they cannot operate safely in an unloaded condition.
CONSTRUCTION
The basic components of a D.C. series motor are the armature, field windings, brush assembly, frame, endbells and bearings.
The armature is the rotating component of the motor and is made of a steel shaft with notched laminations that the armature windings are wound on. On one end of the shaft is the commutator, which consists of copper segments insulated from each other. A brush assembly holds the electrically conductive, carbon graphite brushes, which slide on the commutator segments and provide a means to connect the D.C. power supply to the rotating commutator. The commutator and brushes function as an electro-mechanical switch that changes the direction of current flow in the armature as it rotates. The field windings or magnet is a coil and laminated pole assembly powered by the same D.C power supply as the armature. To correct for armature reaction, interlopes are used to shift the neutral magnetic plane to eliminate brush arcing.
The motor frame is a circular, steel structure that mechanically supports the field poles. The end bells enclose all the components of the motor and are bolted onto the frame. Bearings are pressed into the end bells to provide free movement of the armature.
3.3 OPERATION
Motor action governs the operation of a D.C. series motor and states that a current-carrying coil will generate a magnetic field and if this coil is placed in another magnetic field, a force or torque will be exerted on the coil. This torque will be proportional to both the current in the coil and the strength of the magnetic field it is placed within.
The D.C. series motor’s armature (rotating component) is the previously mentioned current-carrying coil and the field winding (stationary component) of the motor is the other magnetic field. So, when the armature and field windings are energized by a D.C. power supply, current will flow through these windings and generate their respective magnetic fields and will be magnetically positioned in such a manner to cause torque. But this torque will only be sustained if the magnetic relationship of the armature and field are maintained. This is accomplished by the commutator, which switches the current flow and reverses the armature’s magnetic polarity every time the commutator segment passes through a brush, causing the armature to be attracted to the stationary field magnet, thus sustaining unidirectional torque or rotation.
3.4 CHARACTERISTICS
To understand the proper application of D.C. series motors, one must understand the characteristics of torque, speed and armature current relative to load changes. In D.C. series motors, the entire armature current (I armature) passes through the series field windings so the magnetic flux (Φ) produced is proportional to armature current:
Flux Φ α I armature
the torque produced will be proportional to the product of flux and armature current:
Torque α (Flux Φ) I armature
Since Flux Φ α I armature and Torque α (Flux Φ) I armature, it follows that the Torque will be proportional the square of I armature. In other words, in formula form:
Torque α I armature
this means that when a D.C. series motor is first started, very high torque will be produced because armature resistance is low, CEMF is zero and the total D.C. supply voltage will drive current through the armature. This armature current would be unimpeded, causing a very high torque. This characteristic makes D.C. series motors ideal for applications requiring high starting torque.
While torque is proportional to the square of the armature current, motor speed is inversely proportional to armature current.
Thus, the torque-speed characteristic of a D.C. series motor is:
Speed α 1/√T
this characteristic means that as the load on the motor increases, the armature current will increase and the torque will increase causing the motor speed to decrease. Hence, D.C. series motors have poor speed regulation because they are load dependent. It also means that as the load decreases, torque decreases and speed increases. At no load, the motor speed would ramp to an extremely high level that could ultimately destroy the motor. This runaway condition would prove to be a personal safety hazard as well.
Applications
D.C. series motors are ideal for large loads and industrial applications that require high starting torque. In addition, they have poor speed regulation that’s load dependent and exhibit an unstable runaway condition when unloaded. Hence, D.C. series motors should never be used where the loads are intermittent, change frequently, or frequently cycle on/off. For example, a water pump drive that runs constantly and requires only small adjustments to maintain the flow rate would be a good application for a series motor. Conversely, a pump those cycles frequently to maintain a tank water level wouldn’t.
4. DC GENERATOR
4.1 INTRODUCTION
An electrical Generator is a machine which converts mechanical energy (or power) into electrical energy (or power).
4.2 PRINCIPLE
It is based on the principle of production of dynamically or ( motionally) induced e.m.f (Electromotive Force). Whenever a conductor cuts magnetic flux, dynamically induced e.m.f. is produced in it according to Faraday’s Law’s of Electromagnetic Induction This e.m.f. causes a current to flow if the conductor circuit is closed.
Hence, the basic essential parts of an electric generator are:
A magnetic field and
A conductor or conductors which can so move as to cut the flux.
CONSTRUCTION
A single-turn rectangular copper coil abcd moving about its own axis in a magnetic field provided by either permanent magnets or electromagnets. The two ends of the coil are joined to two split-rings which are insulated from each other and from the central shaft. Two collecting brushes (of carbon or copper) press against the slip rings.
4.4 APPLICATIONS
• In series arc lightening this type of generators are mainly used
• It is used in railway service
5. LEAD-ACID BATTERY
5.1 INTRODUCTION
The lead-acid battery was invented in 1859 by French physicist Gaston planet and is the oldest type of rechargeable battery .despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents mean that the cells have a relative for use in motor vehicles to provide the high current required automobile starter motors.
As they are inexpensive compared to newer technologies, lead-acid batteries are widely used even when surge current is not important and other designs could provide high energy densities.
For the roles, modified version of the standard cell may be used to improve storage times and reduce maintenance requirements. Gel-cell and absorbed glass-mat batteries are common in these roles, collectively known as VRLA (valve-regulated lead-acid) batteries
5.2 RECHARGEBLE BATTERIES:
A rechargeable battery or storage battery is a group of one or more electrochemical cells. They are known as secondary cells because their electrochemical reactions are electrically reversible.
Rechargeable batteries come in many different shapes and sizes, ranging anything from a button cell to megawatt systems connected to stabilize an electrical distribution network. Several different combinations of chemicals are commonly used, including: lead-acid, nickel cadmium(NiCad), nickel metal hydride (Nigh), lithium ion (Li-ion), and lithium ion polymer (Li-ion polymer).