- Technical Blog From My Notebook

## Tuesday, April 28, 2020

In this post the detailed syllabus of Sub Engineer, KSEB is explained. The pdf of the syllabus can be downloaded.

## Wiring and Earthing MCQ- Electrical Engineering MCQ

Electrical Engineering MCQ's are given. This will be helpful for Technician Grade Electrical, Electrician, Junior Instructor Electrician, Assistant Engineer Electrical, Sub Engineer Electrical, Poly technic Lecturer etc

## Junior Instructor Electrician Previous Question paper

In this post, the Previous Question paper of Junior Instructor Electrician (Category Code: 726/2014) is given. The PDF can be downloaded at the last. You can watch the Detailed explanations in EEE Mae Easy Youtube Channel.

## Static characteristics of instruments

### What do you mean by the Static characteristics of instruments?

The attributes collectively known as the static characteristics of instruments and are given in the datasheet for a particular instrument.

It is important to note that the values quoted for instrument characteristics in such a data sheet only apply when the instrument is used under specified standard calibration conditions.

Due allowance must be made for variations in the characteristics when the instrument is used in other conditions.

### Which are the Static characteristics of instruments?

The 11 main  Static characteristics of instruments are given below;

1. Accuracy and inaccuracy (measurement uncertainty)
2. Precision/repeatability/reproducibility
3.Tolerance
4. Range or span
5. Linearity
6. Sensitivity of measurement
7. Threshold
8. Resolution
9 Sensitivity to disturbance
10. Hysteresis effects

### 1 Accuracy and inaccuracy (measurement uncertainty)

The accuracy of an instrument is a measure of how close the output reading of the instrument is to the correct value.

In practice, it is more usual to quote the inaccuracy figure rather than the accuracy figure for an instrument.

Inaccuracy is the extent to which reading might be wrong and is often quoted as a percentage of the full-scale (f.s.) reading of an instrument.

If, for example, a pressure gauge of range 0–10 bar has a quoted inaccuracy of +/- 1.0% f.s. (+/- 1% of full-scale reading), then the maximum error to be expected in any reading is 0.1 bar.

This means that when the instrument is reading 1.0 bar, the possible error is 10% of this value.

For this reason, it is an important system design rule that instruments are chosen such that their range is appropriate to the spread of values being measured, in order that the best possible accuracy is maintained in instrument readings.

Thus, if we were measuring pressures with expected values between 0 and 1 bar, we would not use an instrument with a range of 0–10 bar.

The term measurement uncertainty is frequently used in place of inaccuracy.

### 2. Precision/repeatability/reproducibility

Precision is a term that describes an instrument’s degree of freedom from random errors.

If a large number of readings are taken of the same quantity by a high precision instrument, then the spread of readings will be very small.

Precision is often, though incorrectly, confused with accuracy.

High precision does not imply anything about measurement accuracy.

A high precision instrument may have low accuracy.

Low accuracy measurements from a high precision instrument are normally caused by a bias in the measurements, which is removable by recalibration.

### What are repeatability and reproducibility?

The terms repeatability and reproducibility mean approximately the same but are applied in different contexts.

#### Repeatability

Repeatability describes the closeness of output readings when the same input is applied repetitively over a short period of time, with the same measurement conditions, same instrument and observer, same location and same conditions of use maintained throughout.

#### Reproducibility

Reproducibility describes the closeness of output readings for the same input when there are changes in the method of measurement, observer, measuring instrument, location, conditions of use and time of measurement.

Both terms thus describe the spread of output readings for the same input.

This spread is referred to as repeatability if the measurement conditions are constant and as reproducibility, if the measurement conditions vary.

The degree of repeatability or reproducibility in measurements from an instrument is an alternative way of expressing its precision.

### 3. Tolerance

Tolerance is a term that is closely related to accuracy and defines the maximum error that is to be expected in some value.

Whilst it is not, strictly speaking, a static characteristic of measuring instruments, it is mentioned here because the accuracy of some instruments is sometimes quoted as a tolerance figure.

When used correctly, tolerance describes the maximum deviation of a manufactured component from some specified value.

For instance,  electric circuit components such as resistors have
tolerances of perhaps 5%.

One resistor is chosen at random from a batch having a nominal
value 1000W and tolerance 5% might have an actual value anywhere between 950W and 1050 W.

### 4. Range or span

The range or span of an instrument defines the minimum and maximum values of the quantity that the instrument is designed to measure.

### 5. Linearity

It is normally desirable that the output reading of an instrument is linearly proportional to the quantity being measured.

In a plot of the typical output readings of an instrument when a sequence of input quantities are applied to it, the normal procedure is to draw a good fit straight line through the points.

The non-linearity is then defined as the maximum deviation of any of the output readings marked points from this straight line.

Non-linearity is usually expressed as a percentage of full-scale reading.

### 6. Sensitivity of measurement

The sensitivity of measurement is a measure of the change in instrument output that occurs when the quantity being measured changes by a given amount.

Thus, sensitivity is the ratio of scale deflection to the value of measurand producing deflection.

The sensitivity of measurement is, therefore, the slope of the straight line drawn based on the values.

If, for example, a pressure of 2 bar produces a deflection of 10 degrees in a pressure transducer, the sensitivity of the instrument is 5 degrees/bar

(assuming that the deflection is zero with zero pressure applied).

### 7. Threshold

If the input to an instrument is gradually increased from zero, the input will have to reach a certain minimum level before the change in the instrument output reading is of a large enough magnitude to be detectable.

This minimum level of input is known as the threshold of the instrument.

Manufacturers vary in the way that they specify a threshold for instruments.

Some quote absolute values, whereas others quote threshold as a percentage of full-scale readings.

As an illustration, a car speedometer typically has a threshold of about 15 km/h. This means that, if the vehicle starts from rest and accelerates, no output reading is observed on the speedometer until the speed reaches 15 km/h.

### 8 Resolution

When an instrument is showing a particular output reading, there is a lower limit on the magnitude of the change in the input measured quantity that produces an observable change in the instrument output.

Like threshold, the resolution is sometimes specified as an absolute value and sometimes as a percentage of f.s. deflection.

One of the major factors influencing the resolution of an instrument is how finely its output scale is divided into subdivisions.

Using a car speedometer as an example again, this has subdivisions of typically 20 km/h.

This means that when the needle is between the scale markings, we cannot estimate speed more accurately than to the nearest 5 km/h. This figure of 5 km/h thus represents the resolution of the instrument.

### 9. Sensitivity to disturbance

All calibrations and specifications of an instrument are only valid under controlled conditions of temperature, pressure etc.

These standard ambient conditions are usually defined in the instrument specification.

As variations occur in the ambient temperature etc., certain static instrument characteristics change, and the sensitivity to disturbance
is a measure of the magnitude of this change.

Such environmental changes affect instruments in two main ways, known as zero drift and sensitivity drift.

#### what is Zero drift?

Zero drift is sometimes known by the alternative term, bias.

Zero drift or bias describes the effect where the zero reading of an instrument is modified by a change in ambient conditions.

This causes a constant error that exists over the full range of measurement of the instrument.

The mechanical form of a bathroom scale is a common example of an instrument that is prone to bias.

It is quite usual to find that there is a reading of perhaps 1 kg with no one stood on the scale.

If someone of known weight 70 kg were to get on the scale, the reading would be 71 kg, and if someone of known weight 100 kg were to get on the scale, the reading would be 101 kg.

### How can we remove the Zero drift of Instruments?

Zero drift is normally removable by calibration.

In the case of the bathroom scale just described, a thumbwheel is usually provided that can be turned until the reading is zero with the scales unloaded, thus removing the bias.

Zero drift is also commonly found in instruments like voltmeters that are affected by ambient temperature changes.

Typical units by which such zero drift is measured are volts/°C.

This is often called the zero drift coefficient related to temperature changes.

If the characteristic of an instrument is sensitive to several environmental parameters, then it will have several zero drift coefficients, one for each environmental parameter.

#### What is Sensitivity drift?

Sensitivity drift (also known as scale factor drift) defines the amount by which an instrument’s sensitivity of measurement varies as ambient conditions change.

It is quantified by sensitivity drift coefficients that define how much drift there is for a unit change in each environmental parameter that the instrument characteristics are sensitive to.

Many components within an instrument are affected by environmental fluctuations, such as temperature changes: for instance, the modulus of elasticity of spring is temperature-dependent.

Sensitivity drift is measured in units of the form (angular degree/bar)/°C.

If an instrument suffers both zero drift and sensitivity drift at the same time, then the typical modification of the output characteristic is shown in Figure (c)

### 10. Hysteresis effects

The above fig. illustrates the output characteristic of an instrument that exhibits hysteresis.

If the input measured quantity to the instrument is steadily increased from a negative value, the output reading varies in the manner shown in curve (a).

If the input variable is then steadily decreased, the output varies in the manner shown in curve (b).

Two quantities are defined, maximum input hysteresis and maximum output hysteresis, as shown in Figure above.

These are normally expressed as a percentage of the full-scale

Dead space is defined as the range of different input values over which there is no change in output value.

Any instrument that exhibits hysteresis also displays dead space, as marked on Figure explaining hysteresis characteristics.

Some instruments that do not suffer from any significant hysteresis can still exhibit a dead space in their output characteristics, however.

Backlash in gears is a typical cause of dead space and results in the sort of instrument output characteristic shown in Figure below.

Backlash is commonly experienced in gearsets used to convert between translational and rotational motion (which is a common technique used to measure translational velocity).

You can check the previous posts also.

Here there are some books for studying Measurements and Instrumentation and some Electrical & Electronics Text Books

## Types of measuring instruments- www.eeemadeeasy.com

### Instrument types

Instruments can be subdivided into separate classes according to several criteria.

These subclassifications are useful in broadly establishing several attributes of particular instruments such as accuracy, cost, and general applicability to different applications.

1.     Active and passive instruments
2.     Null-type and deflection-type instruments
3.     Analogue and digital instruments
4.     Indicating instruments and instruments with a signal output
5.     Smart and non-smart instruments

Instruments are divided into active or passive ones according to whether the instrument output is entirely produced by the quantity being measured or whether the quantity being measured simply modulates the magnitude of some external power source.

### Example of a passive instrument :

A pressure-measuring device is shown in Figure below.

The pressure of the fluid is translated into a movement of a pointer against a scale.

The energy expended in moving the pointer is derived entirely from the change in pressure measured: there are no other energy inputs to the system.

### Example of an active instrument

A float-type petrol tank level indicator as in Figure below.

Here, the change in petrol level moves a potentiometer arm, and the output signal consists of a proportion of the external voltage source applied across the two ends of the potentiometer.

The energy in the output signal comes from the external power source: the primary transducer float system is merely modulating the value of the voltage from this external power source.

In active instruments, the external power source is usually in electrical form, but in some cases, it can be other forms of energy such as a pneumatic or hydraulic one.

One very important difference between active and passive instruments is the level of measurement resolution that can be obtained.

### 2. Null-type and deflection-type instruments

The pressure gauge just mentioned is a good example of a deflection type of instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer.

An alternative type of pressure gauge is the deadweight gauge shown in Figure below, which is a null-type instrument.

Here, weights are put on top of the piston until the downward force balances the fluid pressure.

Weights are added until the piston reaches a datum level, known as the null point. Pressure measurement is made in terms of the value of the weights needed to reach this null position.

### 3. Analogue and digital instruments

An analogue instrument gives an output that varies continuously as the quantity being measured changes.

The output can have an infinite number of values within the range that the instrument is designed to measure.

The deflection-type of pressure gauge described earlier in this post is a good example of an analogue instrument.

As the input value changes, the pointer moves with a smooth continuous motion.

Whilst the pointer can therefore be in an infinite number of positions within its range of movement, the number of different positions that the eye can discriminate between is strictly limited, this discrimination being dependent upon how large the scale is and how finely it is divided.

A digital instrument has an output that varies in discrete steps and so can only have
a finite number of values.

The rev counter sketched in Figure is an example of a digital instrument.
 rev counter

A cam is attached to the revolving body whose motion is being measured, and on each revolution the cam opens and closes a switch.

The switching operations are counted by an electronic counter. This system can only count whole revolutions and cannot discriminate any motion that is less than a full revolution.

### 4. Indicating instruments and instruments with a signal output

The final way in which instruments can be divided is between those that merely give
an audio or visual indication of the magnitude of the physical quantity measured and
those that give an output in the form of a measurement signal whose magnitude is
proportional to the measured quantity.

The class of indicating instruments normally include all null-type instruments and
most passive ones. Indicators can also be further divided into those that have an analogue output and those that have a digital display.

A common analogue indicator is a liquid-in-glass thermometer. Another common indicating device, which exists in both analogue and digital forms, is the bathroom scale.

The older mechanical form of this is an analogue type of instrument that gives an output consisting of a rotating pointer moving against a scale (or sometimes a rotating scale moving against a pointer).

More recent electronic forms of bathroom scale have a digital output consisting of numbers presented on an electronic display.

One major drawback with indicating devices is that human intervention is required to read and record a measurement.

This process is particularly prone to error in the case of analogue output displays, although digital displays are not very prone to error unless the human reader is careless.

Instruments that have a signal-type output are commonly used as part of automatic control systems.

In other circumstances, they can also be found in measurement systems where the output measurement signal is recorded in some way for later use.

This subject is covered in later chapters. Usually, the measurement signal involved is an electrical voltage, but it can take other forms in some systems such as an electrical current, an optical signal or a pneumatic signal.

### 5. Smart and non-smart instruments

The advent of the microprocessor has created a new division in instruments between
those that do incorporate a microprocessor (smart) and those that don’t

## What is Ohm’s Law? Ohm's Law Statement Formula & Examples

### What is Ohm’s Law?

Ohm’s Law applies to  electric conduction through good conductors.

## TECHNICIAN GR II (ELECTRICIAN) Kerala PSC - KMML Kerala minerals & Metals Ltd

Kerala PSC is conducting an exam for the post of Technician Gr II  (Electrician) in May 2020. This will be a common test for the category numbers 33, 34, 35, 36, 37, 38, 39, 40, 41) Category Number : 61/19, 412/19, 506/19, 542/19, 543/19, 196/19, 200/19, 209/19, 326/19

## TRAINING INSTRUCTOR (ELECTRICIAN) Syllabus Kerala PSC

Kerala PSC is conducting an exam for the post of Training Instructor (Electrician) in May 2020. This will be a common test for the category numbers 102/17, 334/19, 321/19.

## QUALITY ASSURANCE Standards -Dairy Engineering-Technical Superintendent Milk Marketing  Federation ltd

### QUALITY ASSURANCE

HACCP, GMP, IS0 standards, FSSAI, AGMARK, MMPO, PFA:
HACCP, GMP, IS0 standards, and FSSAI are QA systems.

## INDIGENOUS MILK PRODUCTS/ SWEETS-Dairy Engineering-Technical Superintendent Milk Marketing  Federation ltd

Milk plays a significant role as a source of animal protein in the average Indian diet which is predominantly vegetarian.

## ICE CREAM-FSSAI standards - Dairy Engineering-Technical Superintendent Milk Marketing  Federation ltd

### FSSAI definition of ice cream:

According to Food Safety and Standard Regulations 2011, Ice Cream, Kulfi, Chocolate Ice Cream or Softy Ice Cream(hereafter referred to as the said product) means the product obtained by freezing a pasteurized mix prepared from milk and /or other products derived from milk with or without the addition of nutritive sweetening agents, fruit and fruit products, eggs and egg products, coffee, cocoa, chocolate, condiments, spices, ginger and nuts and it may also contain bakery products such as cake or cookies as a separate layer and/or coating.

## Continuous Butter Making -Dairy Engineering-Technical Superintendent Milk Marketing  Federation ltd

### Continuous Butter Making

With increasing volume sales of Table butter, the dairy plants are now switching over from conventional batch butter making to continuous ones, ensuring consistent quality of product throughout the continuous run of the continuous butter making machine.

## Butter making in batch churn-Dairy Engineering-Technical Superintendent Milk Marketing  Federation Ltd

There are four basic stages involved in any butter making process. These include:

## The technology of Milk and Milk Products - The technology of Butter making

The technology of Butter making –
i.Batch and

ii. Continuous Processes

Introduction There are basically two kinds of butter

## Set 2 Dairy Engineering Multiple Choice Questions|Dairy Technology MCQ's|Technical Superintendent Milk Marketing Federation

41. Legal butter must contain at least what percentage of fat?
a. 70 %
b. 80 %
c. 90 %
d. 95 %

## Set 2 Dairy Engineering Multiple Choice Questions|Dairy Technology MCQ's

21. 10-15 % more milk is produced with which growth hormones if injected to
lactating cows?
a. Auxin
b. Bovine Growth Hormone
c. Ethylene
d. None of the above

## Dairy Engineering Multiple Choice Questions|Dairy Technology MCQ's

1. What is the principal carbohydrate in the milks of all mammals?
a. Lactose
b. Glucose
c. Sucrose
d. Fructose

## Technical Superintendent Kerala Milk marketing Federation Limited

Kerala PSC is conducting Exam for Technical Superintendent( Engineering) to the Kerala Milk Marketing Federation Limited on 19 February 2020.

## Detailed SyllabusTechnical Superintendent Kerala Milk marketing Federation Limited

Kerala PSC is conducting Exam for Technical Superintendent( Engineering) to the Kerala Milk Marketing Federation Limited on 19 February 2020. The Syllabus of the Technical Superintendent Milma Exam and the Previous Question paper are given below. you can download the Syllabus and previous Question paper PDF also.

## Electrical Engineering Quiz-Electrical Engineering Mocktest

Hi all, you can attend the Electrical Engineering Quiz and press submit to know the Result. All the Best.