Sunday, March 30, 2014

9

Basic troubleshooting of Electrical components in MCC/Electrical Control Panel/Switch Gear

  • Sunday, March 30, 2014
  • denizen robo
  • 1. SDF (Switch Disconnector Fuse)
    Switch Disconnector Fuse
    Possible Fault:- Fuse Burning. 
    Identification:- Check the fuses continuity with a Multi Meter. 
    Cause:- Over Current, Short Circuit
    Remedy:-Replace the Fuse with same rated(Current and Voltage) new one 

    2.MCCB/MCB (Miniature Circuit Breaker )

    MCB / MCCB
    Possible Fault:- Tripping
    Cause: Short Circuited current.
    Remedy:- Rectify the cause produced the tripping current and once rectified the same. Put ON the MCCB/MCB
    Rating :- Voltage, Current, Withstanding Fault Current

    3.CONTACTOR

    CONTACTOR
    Possible Fault:- Motor not starting.
    Cause:- Contactor Coil faulty, Coil is not getting Power 
    Remedy:- Check the Power Supply voltage from Coil point. If coil is faulty replace with new one.     
    Rating:- Voltage , Current, Maximum fault withstand Current.

    4.OLR (Overload Relay)
    Overload Relay

    Possible Faults:- Motor not starting/Motor tripping continuously
    Cause:- Relay Tripped, Current adjustment is faulty.
    Remedy:- Release the tripped OLR switch, Adjust the current rating according to the Name Plate.
    Ratings:- Current and Voltage.
    5.RELAY
    RELAY

    Possible Fault:-  Not Working.
    Cause: Coil faulty, No power, Contact got damaged
    Remedy:- Check the power Supply voltage, Continuity between contacts, wiring faulty.
    Ratings:- Coil Voltage, Current Ratings, Type of Contact.


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    Wednesday, January 15, 2014

    2

    Names and purpose of different type of Instruments [Part1]

  • Wednesday, January 15, 2014
  • denizen robo
  • absorptiometer
    instrument for measuring solubility of gases in liquids
    accelerometer
    instrument for measuring acceleration or vibrations
    acetimeter
    instrument for measuring strength of vinegar
    acidimeter
    instrument for measuring concentration of acids
    actinograph
    instrument used to calculate time of photographic exposure
    actinometer
    instrument for measuring incident radiation
    aerometer
    instrument for measuring weight or density of gas
    aethrioscope
    instrument for measuring temperature variations due to sky conditions
    alcoholometer
    instrument for measuring proportion of alcohol in solutions
    alcovinometer
    instrument to measure strength of wine
    algometer
    instrument for measuring sensitivity to pain
    alkalimeter
    instrument for measuring strength of alkalines
    altimeter
    instrument for measuring altitude
    ammeter
    instrument for measuring electrical current
    anemograph
    instrument for measuring pressure and velocity of wind
    anemometer
    instrument for measuring wind velocity
    areometer
    instrument used for measuring specific gravity
    arthroscope
    instrument for examining interior of a joint
    atmometer
    instrument for measuring evaporating capacity of air
    audiometer
    instrument for measuring acuity of hearing
    auriscope
    instrument for examining the ear
    auxanometer
    instrument for measuring growth of plants
    auxometer
    instrument for measuring magnifying power
    ballistocardiograph
    instrument for detecting body movements caused by heartbeat
    barograph
    instrument for recording air pressure
    barometer
    instrument for measuring air pressure
    baroscope
    weather-glass
    bathymeter
    instrument for recording contours of deep oceans
    bathythermograph
    instrument for recording water temperature as compared to depth
    bolometer
    instrument for measuring radiant energy or infrared light
    bronchoscope
    instrument for examining the windpipe
    calorimeter
    instrument for measuring absorbed or evolved heat
    cardiograph
    instrument for recording movements of the heart
    cathetometer
    instrument for measuring short vertical distances
    ceilometer
    instrument for measuring height of cloud ceiling above earth
    ceraunograph
    instrument for recording thunder and lightning
    chlorometer
    instrument for measuring amount of chlorine in a solution
    chromatograph
    instrument for performing chromatographic separations
    chromatoptometer
    instrument measuring eyes' sensitivity to colour
    chronograph
    instrument for recording the moment of an event
    chronometer
    instrument for measuring time
    chronoscope
    instrument for measuring very short time intervals
    clinometer
    instrument used to measure slopes and elevations
    coercimeter
    instrument for measuring coercive force
    colonoscope
    instrument for viewing the colon
    colorimeter
    instrument for measuring and determining color
    colposcope
    instrument for viewing the neck of the uterus
    coronagraph
    instrument for viewing the corona of the sun
    coulombmeter
    instrument for measuring electric charge
    coulometer
    instrument measuring amount of substance released in electrolysis
    craniometer
    instrument for measuring the skull


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    Sunday, September 22, 2013

    4

    [Instrumentation Interview Question] What is Thermocouples? Standard Thermocouples

  • Sunday, September 22, 2013
  • denizen robo
  • Thermocouple


    A thermocouple consists of a pair of different metal or alloys joined together at both ends. One end, measuring junction, is placed where temperature is to be measured. The two conductors extend out of the measurement area to the reference junction. An electromotive force (emp or mV) is produced which is function of temperature difference between the two junctions and material of the wires.
    E = k (T1 – T2)
     
    Thermocouple working principle
    Since the mV generated by the thermocouple is the function of temperature difference between the two junctions, control or compensation of reference junction temperature is required.

    Standard Thermocouples

    Seven types of thermocouples (TC) have been given letter designation by ISA (Instrument Society of America). These are listed in table along with normal working temperature measurement range. A brief description of important thermocouples, which are extensively used in steel industries, is produced in the following paragraphs.

                                                               TABLE

    TYPE              COMPOSITION        RANGE          EMF                WIRE
                                                                (Deg C)           (mV)                GAUGE
    B                     Pt-6% Rh vs.               0 to                  0 to                  24
                            Pt-30% Rh                  1820                13.81
    R                     Pt vs    .                       -50 to               -0.226 to          24
                            Pt-13% Rh                  1768                21.10
    S                      Pt vs.                           -50 to               -0.236 to          24
                            Pt-10% Rh                  1768                18.69
    J                       Iron vs.                        -210 to             -8.096 to          8
                            constantan                   760                  42.92
    K                     Chromel vs.                 -270 to             -6.458 to          8
                            Alumel                                    1372                54.87
    T                      Copper vs.                   -270 to             -6.258 to          14
                            constantan                   400                  20.869
    E                      Chromel                      -270 to             -9.835 to          8
                            constantan                   1000                76.358


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    Saturday, September 21, 2013

    2

    [Instrumentation Interview Question] Pressure measurement

  • Saturday, September 21, 2013
  • denizen robo
  • Pressure is defined as force per unit area. Pressure above atmospheric is mostly measured in pounds per square inch (PSI), or in kilo gram per square centimeter (kg/cm2) gauge or absolute. For lower pressure (below about 10 psi), inches or cms. of water or mercury column are frequently used. For near atmospheric pressure, we refer more commonly to millimeters of mercury column (or torr).

    The SI unit of pressure is Newton per square meter, or PASCAL (Pa). One atmospheric pressure (atm) is equal to 101325 Pa or 101.325 Kpa. More recently, bar is also being used for higher ranges. A bar is 0.987 atm, or approximately 14.5 PSI. A conversion table for more commonly used pressure units is given here.

    Pressure Conversion Table:
    From                atmospheric     Psi                   Bar                  mmHg (torr):
    Atmospheric    1.000               14.696             1.0133             760.00
    (1.033 kg/cm2)
    Psi                   0.068               1.000               0.0689             51.50
    Bar                  0.987               14.504             1.000               750.06
    Kg/sq.cm         0.9678             14.223             0.9807             735.56
    MmHg(torr)    0.0013             0.019               0.013               1.00
    Mm(WC)         0.0001             0.0014             0.0001             0.0736HgHJH

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    Friday, September 20, 2013

    6

    [Instrumentation interview question ]What is a ‘controller’? Area of application?

  • Friday, September 20, 2013
  • denizen robo
  • Standalone controller (PID)

    A controller is an instrument used for controlling a process variable (measurement). Its continuously monitors the error signal and gives a corrective output to the final control element.

    a    measurement variable
          desired variable
       deviation
          output

    Measurement variable: It is the demand variable measured and controlled.

    Desired Variable: it is the demand signal (set point) to which the process variable is controlled.

    Deviation: it is the error signal caused by the difference between the measurement and the demand signal.

    Output: It is the corrective signal from the controller to the final control element.
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    Sunday, September 15, 2013

    0

    How a Level troll works? Name the parts of a pneumatic Level troll.

  • Sunday, September 15, 2013
  • denizen robo
  • Level troll-Level measuring instrument

    A Level troll in and instrument used for measuring the liquid level between two known points. The Level troll works on the buoyancy principal. Leveltrol has a float, which submerses proportionately with liquid level raise in the float chamber. The amount of submersion of the dis placer depends on the liquid density, which produces a torque. The amount of torque produced in measured in terms of % of level.

    Parts of Level troll:

    Float chamber, Float, Torque lever, Knife edge, Feedback Bellows, Air Relay, Restriction, Flapper, Nozzle, Feedback link, Density range, Action change lever, HP and LP flange,
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    Saturday, September 22, 2012

    4

    Basic Concept of PLC (Programmable logic controllers).

  • Saturday, September 22, 2012
  • denizen robo
  • What is PLC?

     PLC is a solid state device which control output device based which control output device based on input device and user developed program. It performs relay equivalent functions.Modern PLCs can perform complex operations like PID control and Analog signal processing.



     Advantages of PLC over relay logic.

    Cost effective.
    Easy maintenance
    User friendly
    Easy programming
    Easy troubleshooting

    Components of a PLC

    CPU (Central processing unit )
    I/O Modules (Input ouput module)
    Communication module

    PLC programming languages

    Ladder logic
    Functional block diagram
    Structured test
    Sequential flow chart
    Instruction list

    Download free PLC programming software with Simulator
    Next blog post is about "How to do ladder logic programming in allen bradly PLC.

    Related posts:
    Difference between control panel and MCC
    What is control panel? 
    Basic networking : Industrial automation 
    How to read electrical relay diagram

    Read more...

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