Electromechanical Relays

As the name indicates, electromechanical relays use the principle of inter conversion between electrical and mechanical energies. The most common type of electromechanical relay is the induction coil.

Basic operation of an electromechanical relay:

1. The relay used should activate the circuit breaker when an over current occurs, thereby the circuit breaker disconnects the current flow and prevent the circuit components from damages.
2. Usually a current transformer is used and current flows through its secondary only when over current flows.
3. The current across the secondary of the transformer energizes the relay coil which in turn breaks the circuit connection in the circuit breaker.
4. Thus further damages are prevented.

In the case of induction relays, there may be one or more exciting coils wound around a magnetic core. Due to flow of current in the exciting coil, the electromagnetic torque is produced which rotates the rotor.

This rotation of rotor is translated into mechanical action for closing of relay.

Types of induction relay:

1. Induction disk relays
2. Induction cup relays
3. Hinged armature relays

Disadvantages of Electromechanical relays
Electromechanical relays are widely used for various applications but they suffer the following drawbacks:

1. High burden on instrument transformers
2. High operating time due to high inertia
3. Contact pitting and corrosion
4. Contact Racing: The Phenomenon by which the inertia of the moving parts causes unwanted connections in the circuit, which makes relay co-ordination difficult.
5. Requires frequent maintenance as there are several moving parts.
6. It is easily affected by shocks and vibrations from outside

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Wireless based Instrumentation Projects (NON IEEE)

WIRELESS MOUSE CONTROLLED DISH ANTENNA

Objective of the project is to control the dish antenna position according to the mouse movement through zigbee transmission with help of microcontroller.

Scope:
In current process dish antenna is controlled manually by men or some wired remote. It’s difficult to change the position of the dish in a short time. So this project overcomes this problem.

WIRELESS BUILDING HEALTH MONITOR

Objective of the project is to monitor the health of the building through zigbee transmission with help of microcontroller.

Scope:
Nowadays there are so many buildings are become weak due to high temperature and increase of moist level. To avoid these kinds of problem we need to notice the building’s temperature and moisture status. In order to do that microcontroller is placed inside the wall of the building with sensors and zigbee. Through zigbee communication we can monitor the temperature, vibration and moist of the building from pc itself.

WIRELESS SENSOR NETWORK FOR POLICE PETROL

The objective of this project is to track the location using GPS receiver for the police patrol.

Scope:
In the last decade the number of deaths and fatal injuries from traffic accidents has been increasing rapidly. So, to avoid this, automatically transmit GPS (Global Positioning System) location to the police station with in a second. They will find the exact location by latitude and longitude values. The alarm will ON with the help of driver circuit when accident place reaches.


REMOTE RIVER LEVEL SENSOR NETWORK

The objective of this project is to monitor the river water level using the flow sensors and display on the LCD Display.

Scope:
This paper evaluates an automated water level monitoring network. This network contains multiple nodes on which measuring modules are installed. These modules collect raw data and transmit them periodically to a central monitoring system.
This monitoring system monitors and processes the raw data and extracts information. Based on this information, various approximations are made such as water level rise rate, time remaining to exceed the critical level etc. The whole network is implemented as a prototype.

PILGRIMS TRACKING USING WIRELESS SENSOR NETWORK

The objective of this project is to track location of the pilgrims using zigbee and monitoring in pc with the help of google map.

Scope:
In last decades if someone lost their path, it is so difficult to find their location but, by using this technique easily find their paths and rescue is very easy buy tracking GPS location.
We can track not only pilgrims path can also track anyone who having GPS receiver with them. GPS will provide latitude and longitude value, we can get the exact position by plotting these latitude and longitude in google map.


REAL TIME CROP FIELD MONITORING USING ZIGBEE

Objective:
The objective of this project is to monitor the temperature, PH and moister.

Scope:
In this project we are continuously monitor the temperature, PH and moister by the help of temperature sensor, PH sensor and moister senor. These values are continuously received to the PC. In we can monitor these parameters.

AD-HOC NETWORK BASED FLOOD MONITOR AND ALARM

Objective:
The main objective of this project is to monitor the flood using flow sensor. Flow sensor is used to measure the flow rate of the water.

Scope:
It is one of the best methods to identify the flood. This project consists of two flow sensor at different places, and to monitor the flow rate of water. If the flow rate is increased above the set rate in the two locations, the alarm will indicate and inform that flood.

TOUCH SCREEN AND ZIGBEE BASED CONTROL SYSTEM FOR APARTMENTS

Objective:
The objective of this project is to control the appliances through touch screen and ZIGBEE.

Scope:
In this project we are controlling the home appliances with the help of touch screen and ZIGBEE. The different places in touch screen produce different values. These values will transmit through ZIBEE. In the receiver side ZIGBEE receives and controls the relay.

MULTIPLE WIRELESS ELECTRONIC NOTICE BOARD

The objective of this project is to design the electronic notice board using the LCD and the wireless communication.

Scope:
Now a day’s college and school are using various type of method to convey the message to the student. In this project we convey the message to easily. We are display the data in LCD display. Project consists of two ZIGBEE receiver and two microcontrollers. The LCD display will display while the received data consist of specified symbol or character.

BLUETOOTH BASED HOME APPLIANCES CONTROLLER

Objective:
The objective of this project is to control the home appliances through Bluetooth technology. 

Scope:
In this project we are controlling the home appliances with the help of Bluetooth. One part of Bluetooth device is connected with PC. Another part is connected with controller. The commands sends from the PC is transmitted through Bluetooth device. After receiving the commands in the receiver Bluetooth, the commands are given to the microcontroller. According to the commands the home appliances will control by the help of relay.


More projects and posts coming soon.

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Interferometer

Basic Principle of Interferometer

Interferometer is a precise instrument for flow visualization. The variation of refractive index of the flowing gas with density is the basic principle used in thses system. The principle of interference of light waves is used. At a phase angle, the number of fringes are in relation to change in density with respect to the zero fringe condition.

Description of Interferometer

The arrangement consists of the following:

1. Two windows to form a test section
2. A light source
3. Two Lenses L1 and L2
4. Two beam splitters B1 and B2
5. Two mirrors M1 and M2
6. A display Screen.

Operation of Interferometer

1. Light rays from a source are collimated with a lens L1. That is, the light rays become a parallel beam of rays when they come out of the lens L1.
2. This collimated light rays are then split by a beam splitter B1. The two beams traverse at right angles to each other.
3. That is the beam splitter B1 makes half of the light to go to mirrir M1. The remaining half is reflected towards mirror M2.
4. Beam 1 is made to pass through the test section (to experience the flow filed) and beam 2 travels an alternate path, but of equal length.
5. The two beams are agin brought together with the help of beam splitter S2 and are then focused onto the display screen.
6. Because of the variation in the refractive properties of the flowing gas in the test section, beams-1 will have a travel path of different optical length when compared to that of beam 2. Beacuase of this, the two beams will be out of phase and will interface when they are joined together at B2. This causes alternate bright and dark regions called fringes on the display screen.
7. The number of fringes will be a function of the difference in the optical length of the two beams. That is, for a difference in the path lengths of one wavelength, one fringe will appear. For a difference in the path lengths teo wave lengths, two fringes will appear and so on.
8. It is to be noted that if medium I the test section has the same optical properties as that of the medium experience by beam 2, no fringe shifts will appear.
9. Thus by observing ( and photographing) the interference effects, direct measurement of density variations of the flow in the test section can be obtained/ visualized.
10. The only disadvantage in yusing this instrument is that it is difficult to align the setup to get beams that have travel paths of the same optical lengths.

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Laser Doppler anemometer

Doppler Effect is a method for measuring linear velocity. When a narrow laser beam ( or radio beam or ultrasonic beam) is focused on an abject, the beam will be reflected back to the source. But if the object is moving, the frequency of the signal received back will differ from that of the transmitted signal. This difference in frequency (Doppler shift) becomes a measure of the velocity of the object .

LDA is used to measure flow (especially, high frequency turbulence fluctuations). This device can measure velocity of flow precisely and they don’t disturb the flow during the measurement process.

Description of Laser Doppler anemometer

The main parts of this device are as follows

1. A laser source (an argon laser or He-Ne laser).
2. A beam splitter that splits the laser beam into two equal intensity beams.
3. Alens to focus the two split lazer beams at an intersection point.
4. A photomultiplier tube (PMT)

For a flow whose velocity is to be determine, it is to be noyted that the flow should contain small particles to scatter the light. The particle concentration should be very small.

Operation of Laser Doppler anemometer

1. The laser source sends a beam that is split by a beam splitter into two beams.
2. The two parallel beams are focused by the lens L1 such that they intersect at a point in the test section were flow ( with particles ) exists. In the region of intersection, interference fringes are formed.
3. The particles (carried along with the flow) that pass through the intersection of the beams scatter the light from both the beams.
4. The scattered light experiences a Doppler shift in frequency that is directly proportional to the flow velocity.
5. The light is collected by a photomultiplier tube (PMT). The device is constructed such that the direct and scattered beams travel in the same optical path so that an interference will be observed at the PMT that is proportional to frequency shift. This shift then gives an indication of flow velocity.
6. A signal processor is used to retrieve velocity data from the PMT.

Advantages of Laser Doppler anemometer

1. The device does not disturb the flow during measurement
2. The device measure velocity directly
3. Volume of sensing part can be very small
4. Highly accurate
5. Can be used to measure flow of both gases and liquids.

Disadvantages of Laser Doppler anemometer

1. Requires transparent channels
2. Cannot be-used on clean flows

Applications of Laser Doppler anemometer

1. Wind tunnel studies
2. Blood flow measurement
3. Sensing of wind velocity
4. Used in the field of combustion

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Strain Gauge Accelerometer

Basic Principle of Strain Gauge Accelerometer

When a cantilever beam qattached with a mass at its free end is subjected to vibration, vibrational displacement of the mass takes place. Depending on the deisplacement of the mass, the beam deflects and hence the beam is strained. The resulting strain is proportional to the vibration displacement of the mass and hence the vibration/acceleration being measured when calibrated.

Description of Strain Gauge Accelerometer

The main parts of a strain gague accelerometer are as follows:

• A cantilever beam fixed to the housing of the instrument.
• A mass is fixed to the free end of the cantilever beam.
• Two bounded strain gauges are mounted on the cantilever beam as shown in diagram.
• Damping is provided by a viscous fluid filled inside the housing.

Operation of Strain Gauge Accelerometer

• The accelerometer is fitted on to the structure whose acceleration is to be measured.
• Due to the vibration, vibrational displacement of the mass occurs, causing the cantilever beam to be strained.
• Hence the strain gauges mounted on the cantilever beam are also strained and due to this their resistance change.
• Hence a measure of this change in resistance of the strain gauge becomes a measure of the extent to which the cantilever beam is strained.
• But the resulting strain of the cantilever beam is proportional to the vibration/acceleration and hence a measure of the change in resistance of the strain gauges becomes a measure of vibration/acceleration.
• The leads of the strain gauges are connected to a wheat stone bridge whose output is calibrated in terms of vibration/acceleration.

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SAYBOLT VISCOMETER (EFFLUX CUP VISCOMETERS)

Definition of SAYBOLT VISCOMETER
A device used to measure the viscosity of a fluid. The saybolt viscometer controls the heat of the fluid and the viscosity is the time is takes the fluid to fill a 60cc container.

Efflux cup viscometers are most commonly used for fieldwork to measure the viscosity of oils, syrups, varnish, paints and Bitumen emulsions. The testing procedure is quite similar to the capillary-tube viscometers where efflux time of a specified volume of fluid is measured through fixed orifice at the bottom of a cup to represent the viscosity of the fluid. Since the viscosity of Newtonian liquid are independent of dimensions of viscometer used, it is possible to convert the efflux times to kinematic viscosities by conversion charts or by formulas suggested by the equipment manufacturers.

To obtain high accuracy the liquid holding vessel and orifice are temperature controlled by immersing them in a thermostatically controlled bath. The saybolt viscometer, one of the efflux cup viscometers is the standard instrument for testing petroleum products. There are three types of orifices available-Universal, Furol, Asphalt.

The furol and asphalt orifices, respectively, have an efflux time of approximately, one-tenth and one-hundredth that of the universal orifice. The cup orifice combination should be selected to provide an effllux time within the range of 20 to 100 seconds. Of these types, the universal orifice(saybolt universal viscometer) is most commonly used and its efflux time is designated as saybolt universal seconds(SUS).The universal viscometer measures the time required for 60 cc of sample fluid to flow out through an orifice having dimensions of 0.176 cm in diameter and 1.225 cm in length. Saybolt universal seconds (t) can be converted to kinematic viscosity (v) by the following equations:

When t < 100 secs, v = 0.226t - 195/t Centistokes
When t >100 secs, v = 0.220t - 135/t Centistokes

The viscosity determinations should be conducted in a room free from drafts and rapid changes in temperature the highest degree of accuracy.

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Lead Control Systems Engineer Wanted in london

Status:	Staff
Location:	London, UNITED KINGDOM
Advert Published:	12 Aug 2012
Expiry date:	11 Sep 2012
Talascend Ref. No.:	55623
OilCareers Ref. No.:	J796583

Apply here : http://www.oilcareers.com/content/jobsearch/job_advert.asp?jobadid=796583

Position Duties/Responsibilities:

· The Chief Engineer of Control Systems shall assign a Lead Engineer to a project.
The Lead Engineer shall have extended experience in the Oil, Gas and Chemical (OG&C) contracting industry with experience in lead positions managing a team of at least 15 engineers. In addition, the Lead Engineer shall have hands-on experience of project execution through a variety of phases including conceptual design, feasibility studies, front-end design, detailed engineering design and procurement of instrumentation and control systems equipment.

· The Lead Engineer shall report to the Project Engineering Manager assigned to the project and functionally to the discipline Chief Control Systems Engineer.

· The Lead Engineer shall be responsible for planning, organizing, monitoring, reporting, coordinating and controlling the control system scope of work for the assigned project within agreed man-hour budget, schedule and quality standards.

· The Lead Engineer shall interface with the Client representatives to ensure all customer expectations are met.

· The Lead Engineer shall ensure that the project scope is fully understood by self and communicated to all team members.

· The Lead Engineer is responsible for completing staff employee annual performance appraisals and for coaching and developing control systems staff to professional status where required.

· The Lead Engineer may be required to assist the Chief Control Systems Engineer with input to proposals, corporate workshop activities, developing standards, developing technical work practices, interviewing control systems engineers including graduates, developing execution strategies and performing technical audits.

· Commercial awareness and leadership skills are important attributes of a good Lead Engineer.

· The Lead Engineer shall be a team player, goal oriented in so far as the production of deliverables and achievement of milestones as well as taking ownership of tasks and the responsibility for their outcome.

· He or she will also be an effective administrator and a good communicator.

· The Lead Engineer must be familiar with European and American Standards and their application as well as industry trends and their likely impacts.


Required Qualifications and Position Skills

. Masters or Honours degree in Control Systems, Electrical, Electronic or Mechanical Engineering

. Professional Engineer (Chartered Engineer, Fellow or equivalent)

. Proficient user of office automation packages such as Microsoft Word, Excel, Power Point and Access

. SPI user for the preparation of instrument indices and datasheets – rather than being a proficient hands-on user Lead Engineer should understand how SPI is used

. Document Management, Scheduling, Material Requisition Tool

Additional requirements:

Candidates must be prepared for international travel on business trips and or project assignments to site.

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Electrical Torsion Meter (Torque Measurement using slotted Discs)

Basic principle

Due to the applied torque, there is a relative displacement between the two slotted discs. Due to this relative displacement of the slotted discs, a phase shift exists between the pulse generated by the transducers. When these pulses are connected to an electronic unit, it will show a time lapse between the two pulses. This time lapse between the two pulses is proportional to the twist of the shaft and the torque of the shaft.

Description of Electrical Torsion Meter

1. The main parts of an electrical torsion meter are as follows:
2. A shaft connected between a driving engine and a driven load.
3. Two slotted discs attached on either side of the shaft.
4. Transducer (magnetic or photo electric ) to count pulses from the slotted disc.

Operation of Electrical Torsion Meter

1. The teeth produce voltage pulses in the transducers.
2. When torque is not applied on the shaft, the teeth of the bth the discs perfectly align with each other and hence he voltage pulses produced in the transducers will have zero time difference.
3. But when torque is applied on the shaft, there is a relative displacement of the slotted discs due to twist experienced by the shaft and hence the teeth of both the discs will not align with each other and hence the voltage pulses produced in the transducer will have a time difference (that is , time lapse).
4. This time lapse between the pulses of the two discs is proportional to the twist of the shaft and hence the torque of the shaft.
5. A measure of this time lapse becames of torque when calibrated.

Application of Electrical Torsion Meter

1. Used to measure torque on rotation shafts.

Advantages of Electrical Torsion Meter

1. There are no signal leakage problems.
2. There is no noise creation.

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Seismic – Displacement Sensing Accelerometer

Basic Principle

When a spring – mass – damper system is subjected to acceleration, the mass is displaced, and this displacement of the mass is proportional to the acceleration. Hence a measure of displacement of the mass becomes a measure of acceleration.

Description

The main parts of a seismic accelerometer are as follows:

1. A seismic mass is suspended from the housing of the accelerometer through a spring.
2. A damper is connected between the seismic mass and the housing of the accelerometer.
3. The seismic mass is connected to an electric displacement transducer.

Note: there are two types of seismic – displacement sensing accelerometers namely.

1. Linear seisimic accelerometer.
2. Rotational Seismic Accelerometer.

Both of the above mentioned seismic accelerometers work on the same principle and are shown in diagram.

Operation

1. The accelerometer is fitted on to the structure whose acceleration is to be measured.
2. Due the acceleration, the seismic mass experience a displacement and this displacement of the mass is proportional to the acceleration.
3. As the mass is connected to an electric displacement transducer, the output of the transducer depends on the extent – to which the mass is displaced.
4. Hence the output of the transducer is calibrated to give a direct indication of the acceleration characteristics of the structure.

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What is a Magnetic Tape Recorders

Before explaining about magnetic tape recorders, I will tell you what a recorder is and what the uses of the recorder are?


A recorder is used to produce a permanent record of the signal that is measured.

A record is used to analyse how one variable varies with respect to another and how the signal saries with time.

The objective of a recording system is to record and preserve information pertaining to measurement at a particular time and also to get an idea of the performance of the unit and to provide the results of the steps taken by the operator.

The basic components of a general recorder are an operating mechanism to position the pen or writer on the paper and a paper mechanism for paper movement and a printing mechanism.

Okay, now you know what is a recorder, why it is used and where it is used. Now I will explain about magnetic tape recorder.

A magnetic tape recorder is used to record data which can be retrieved and reproduced in electrical form again. This recorder can record signals of high frequency.

Description of Magnetic Tape Recorders:

The magnetic tape is made of a thin sheet of tough plastic material; one side of it is coated with a magnetic material (iron oxide). The plastic base is usually polyvinyl chloride (PVC) or polyethylene terephthalate. Recording head, reproducing head and tape transport mechanism are also present.

Operation of Magnetic Tape Recorders:

1. The recording head consists of core, coil and a fine air gap of about 10 micrometer. The coil current creates a flux, which passes through the air gap to the magnetic tape and magnetizes the iron oxide particles as they pass the air gap. So the actual recording takes place at the trailing edge of the gap.
2. The reproducing head is similar to that of a recording head in appearance. The magnetic tape is passes over a reproducing head, thereby resulting in an output voltage proportional to the magnetic flux in the tape, across the coil of the reproducing head. Thus the magnetic pattern in the tape is detected and converted back into original electrical signal.
3. The tape transport mechanism moves the tape below the head at constant speed without any strain, distrortion or wear. The mechanism much be such as to guide the tape passed by the magnetic heads with great precision, maintain propoer tension and have sufficient tape to magnetic head contact.

Advantages of Magnetic Tape Recorders:

1. Wide frequency range.
2. Low distortion.
3. Immediate availability of the signal in its initial electrical form as no time is lost in processing.
4. The possibility of erase and reuse of the tape.
5. Possibility of playing back or reproducing of the recorded signal as many times as required without loss if signal.

Applications of Magnetic Tape Recorders:

1. Data recording and analysis on missiles, aircraft and satelites.
2. Communications and spying.
3. Recording of stress, vibration and analysis of noise.

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