Switch Gear

By

denizen robo

-

March 30, 2014

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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.

Names and purpose of different type of Instruments [Part1]

By

denizen robo

-

January 15, 2014

0

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

What is Thermocouples? Standard Thermocouples

By

denizen robo

-

September 22, 2013

0

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

Pressure measurement

By

denizen robo

-

September 21, 2013

0

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 0.0736

What is a ‘controller’? Area of application?

By

denizen robo

-

September 20, 2013

0

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

c 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.

How does a Level troll work? Name the parts of a pneumatic Level troll.

By

denizen robo

-

September 15, 2013

0

Displacer level instruments use the Archimedes Principle to measure the level of a liquid by measuring the weight of a rod that is immersed in the process liquid. As liquid level rises, the displacer rod experiences a greater buoyant force, appearing lighter to the sensing instrument, which interprets the loss of weight as a rise in level and transmits a proportional output signal.

Working of Level Troll:

A Level troll is an instrument that measures the level of liquid between two known points.
This level troll instrument is a displacement and torque tube type of instrument.
The working of level troll is based on the principle of the effect of Buoyancy.
This level troll is a special instrument used to manage the level of fluid entering the tank by adjusting a level control valve.
Due to this buoyancy effect, the displacer seems to be lighter than actual when immersed in process fluid or water,
As the liquid level builds up inside the cage it experiences a larger and larger buoyant force that makes the displacer seems to appear to weigh lighter which relieves some of its weight than actual.
The lever shifts upwards a little bit that twists the torque tube inside the instrument and this metal rod twists as well bringing the flapper closer to the nozzle building up back pressure this is then amplified by the pneumatic relay which then fills up the bourdon tube and makes to pull away.

This is a motion balance instrument because the motion of the flapper nozzle is matched by the motion of the bourdon tube.

The apparent weight of the displacer changes accordingly with respect to the rise or drop of the liquid level.

This slight twisting motion of the rod is noticed at the end isolated from the pressure of the process fluid.

A 20 PSI working supply air pressure is continuously provided by an air pressure regulator with filter assembly for the pneumatic level troll.

The pressure required to fill the bourdon tube becomes a pneumatic output signal of 3 to 15 PSI.
The sensor may be a torque tube that detects the change in weight and then interpreted it into the fluid level.

This level troll is attached to a multi-tool proportional controller consisting of a setpoint adjustment, proportional band, and motion balance mechanism for performing proportional loop control.

The term displacer level troll is known as a float by some people, but actually, the word float is not exact because it will not float on a liquid level instead it hangs within a liquid and experiences a buoyant force proportional to liquid level.

The mechanism called the torque tube present inside is a spring steel tube that can twist back and forth.
The lever placed over here upon which the displacer hangs exerts a torque on that tube that twists a small metal rod attached to a flapper and nozzle assembly.
Level-troll has a float, which is immersed in proportion to raise in liquid level inside the float chamber.
The amount of immersion of the displacer depends on the density of the process fluid or liquid to develop torque.
The rate of torque developed is measured in terms of percentage (%) of level.

Specific gravity is defined as the factor within the process that may affect the span adjustment apart from the length of the fixed displacer

The displace height extends between two points A and B as shown in the figure above.

Name the various parts of a pneumatic Level troll:

Parts of the pneumatic Level Troll are shown with the diagram below:

Torque Arm: The torque Arm is a suspension component mounted on a rear-wheel drive axle.

Torque Rod: The torque Rod is the connection element used to connect the axle to the chassis.

Torque Tube: Torque Tube is a power transmission system that consists of a large diameter stationary housing between the transmission and rear end to enclose a rotating tubular steel or small-diameter solid drive shaft

Knife Edge: Knife Edge A piece of steel sharpened to an acute angle resting on a smooth surface functioning as the axis of motion of a pendulum to oscillate with the least possible friction.

Nozzle: A nozzle is often a pipe or tube of varying cross-sectional area to control the flow of a fluid.

Nozzle & Flapper: The nozzle and flapper mechanism is a displacement-type detector that converts mechanical movement into a pressure signal by covering the nozzle, These devices work in harsh industrial environments, need little maintenance, and don’t cause an explosive risk in potentially hazardous atmospheres.

Basic Concept of PLC (Programmable logic controllers).

By

denizen robo

-

September 23, 2012

0

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.

internal_architecture_of_programmable_logic_controllers_PLC_concept

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

How to Calibrate Differential Pressure Level transmitter with actual pressure

By

denizen robo

-

September 19, 2012

0

DP level transmitter with actual pressure

*Hook up HART Communicator and verify some parameters by refer to data sheet. Typical parameters are, tag number, PV, LRV and URV.*Isolate the instrument from the process.
*Release both pressure and drain low side liquid only through manifold drain.

PRECAUTION 1:

*During this process, please do not open the equalizing valve at the manifold.
*Open both plug at seal pot
*Top up the seal liquid for low side until half of seal pot.
*Remove the tubing at high side of the flange (not at the manifold side) to drain remaining liquid in equalizing tube.

PRECAUTION 2:

*Do not remove the process fluid in B. Please ensure it is full with process liquid.
*Install back both plug and connect back tubing at high side of the flange
*Hook up a multimeter in series with the signal to the DCS to measure current signal.
*Open low side (top) isolation valve only and high side (bottom) isolation valve remain closed
Multimeter should show 4mA If not, do zero adjustment at transmitter using HART Communicator.
Isolate back low side (top) isolation valve and released the pressure through high side vent valve seal pot.
Close the vent at seal pot

*Fill up the equalizing tube until full with product by removed the top fitting and slowly open the isolation valve (high side) until the equalizing tube is full (or up to 100% level) with product. Close the high side isolation valve.
*Install back any fitting that was remove for filling up the equalizing tube
*Open low side (top) isolation valve only and high remain closed.Multimeter should show 20mA
If not, do span adjustment at transmitter using HART Communicator

Note:
The reason to open the low side (top) isolation valve is to get the actual pressure vessel

Example Calculation:
Product S.G=0.89
Glycol S.G = 1.02
A= 2000mm (measurement length)
B= 100mm (off set)
C=A+B=2100mm
Dp = pressure at high side – pressure at low side
LRV = (B x Product S.G) – (A x Glycol S.G)
= (100mm x 0.89) – (2000 x 1.02)
= 89 – 2040
= -1951 mmH2O
URV = (C x Product S.G) – (A x Glycol S.G)
= (2100mm x 0.89) – (2000 x 1.02)
= 1869 – 2040
= -171 mmH2O

Note:

LRV and URV calculation may have small variation as compare with HART communicator reading due to calibration with actual pressure.

How to calibrate Dp level transmitter for low side dry leg

By

denizen robo

-

August 1, 2012

0

Differential level transmitter for low side dry leg

Calibration Procedure:

*Hook up HART Communicator and verify some parameters by refer to data sheet. Typical parameters are, tag number, PV, LRV and URV.
*Isolate the instrument from the process.
*Remove connection at manifold to the process after release the process pressure
*Connect pressure calibrator to high side of manifold
*Expose the low side to atmosphere
*Hook up a multimeter in series with the signal to the DCS to measure current signal.
*Apply pressure as per data sheet LRV
Multimeter should show 4mA
If not, do zero adjustment at transmitter using HART Communicator
*Apply pressure as per data sheet URV
Multimeter should show 20mA
If not, do span adjustment at transmitter using HART Communicator
*Verify the linearity by increasing and decreasing the pressure (0%,25%,50%,75%,100%,75%,50%,25% and 0%of range)

Note

LRV and URV range from data sheet should include the pressure effect from bottom flange height to the transmitter and the SG of process liquid.

Example calculation
S.G=0.89
A= 2000mm (measurement length)
B= 100mm (off set)
C=A+B=2100mm
Dp = pressure at high side – pressure at low side
LRV = (B x S.G) – pressure at low side
= (100mm x 0.89) – 0
= 89 mmH2O
URV = (C x S.G) – pressure at low side
= (2100mm x 0.89) – 0
= 1869 mmH2O

How to Calibrate Offset Displacer Level Transmitter

By

denizen robo

-

July 15, 2012

0

How to Calibrate Offset Displacer Level Transmitter

Procedure:

*Hook up HART Communicator and verify some parameters by refer to data sheet. Typical parameters are, tag number, PV, LRV and URV.
*Isolate the instrument from the process.
WARNING – If the process is hazardous, please unsure proper flushing is done to remove the entire hazard.
Remove isolation drain valve and open the vent flange
*Connect water pump to drain line and line up the reference tube
*Calculate the new measurement to get equivalent up trust force with S.G and length
*Mark on the chamber for reference calibration
*Hook up a multimeter in series with the signal to the DCS to measure current signal.
*Apply water level until 0% marking on chamber
*Multimeter should show 4mA
*If not, do zero adjustment at transmitter using HART Communicator
Apply water level until 100% marking on chamber
Multimeter should show 20mA
*If not, do span adjustment at transmitter using HART Communicator
Verify the linearity by increasing and decreasing the pressure (0%,25%,50%,75%,100%,75%,50%,25% and 0%of range)

Example calculation:

Low S.G=0.802
High S.G= 0.992
A= 810mm (measurement length)
B= 410mm (off set)
C=A+B=1220mm (Displacer length)
0% = (High S.G x off set length) + (low S.G x A)
= (0.992 x 410) + (0.802 x 810)
= 406.72 + 649.62
= 1056.34mm
100% = (High S.G x C)
= (0.992 x 1220)
= 1210.24mm

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

Names and purpose of different type of Instruments [Part1]

What is Thermocouples? Standard Thermocouples

TABLE

Pressure measurement

What is a ‘controller’? Area of application?

How does a Level troll work? Name the parts of a pneumatic Level troll.

Working of Level Troll:

Name the various parts of a pneumatic Level troll:

Basic Concept of PLC (Programmable logic controllers).

How to Calibrate Differential Pressure Level transmitter with actual pressure

DP level transmitter with actual pressure

PRECAUTION 1:

PRECAUTION 2:

Note:

How to calibrate Dp level transmitter for low side dry leg

Differential level transmitter for low side dry leg

Calibration Procedure:

Note

How to Calibrate Offset Displacer Level Transmitter

Procedure:

Example calculation:

Related post:

Calibration displacer type level transmitter
Calibration flow transmitter – DP type
Calibration Differential pressure transmitter

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