Running head: ELECTRICAL AND TRANSFORMERS 1

Electrical and Transformers

Name

Institution Affiliation
ELECRICAL AND TRANSFORMERS 2

Abstract

This paper explores on published articles that report on results from research conducted on

online (internet) and offline (non-Internet) relationships to motors and transformers, their

functionality and what they are composed up of. The articles, however, vary in their

definitions, functions, and components. This chapter is an introduction to motors and

transformer fundamentals. It describes the basic principles for the three-phase motor and a

three-phase, their functions in a mechanical room of a commercial building. The objective of

this research is to contribute towards familiarizing with the three-phase motors and

transformers for a commercial building and also to be familiarize with the operational,

maintenance and troubleshooting.

Electrical and Transformers

A transformer is one of the most common devices found in electrical system that links

the circuits that are operating at different voltages. Transformers are widely used in

applications where Alternative Current (AC) voltage transition is required from one voltage

level to another. The use of transformer in AC circuits depending on the specifications of the

electrical equipment/system where charge can either decrease or increase the voltage and

currents. Different systems use a wide range of transformers, including transformers of

power, instruments and pulse. According to Georgilaskis (2009) defined a transformer as a

static machine that, by electromagnetic induction, transmits electrical power from one

alternative device voltage level to another without changing the frequency.

Transformer has two or more winding also known as coils that are wrapped around a

Ferro-magnetic core. These windings are not electrically connected, but they are magnetically

coupled, that is, the only connection between the windings is the magnetic flux present within

the core. One of the transformer coils, the primary winding, is connected to an alternating

current electric power source. The second transformer coil, the secondary winding, supplies

electric power to loads. The electrical energy received by the primary winding it first

converted onto magnetic energy that is reconverted back into a useful electrical energy in the

secondary winding (and tertiary winding if it exists).

A basic three-phase transformer comprises of three sets of primary coils on the same

iron core, one for each phase, and three sets of secondary coil connected. It is possible to use

separate single-phase transformers and interconnect them externally to achieve the same

results as a 3-phase system[ CITATION MEE08 \l 2057 ]. Primary windings are connected in one

of a couple ways. The two most common configurations are the delta, where one winding's

polarity end is connected to the next non-polarity end, and the wye, where all three non-

polarities (or polarity) end are linked together. The secondary windings are similarly related.
ELECRICAL AND TRANSFORMERS 4

This means that a 3-phase transformer may have the same (delta-delta) or different (delta-

wye) connected to its primary and secondary windings.

A motor is an extended version of a transformer. Motor is defined as an electrical

device that transforms electrical energy to mechanical energy. Most electric motors work

through the interaction between the magnetic field of the motor and the electrical current in a

wire winding to produce force in the form of a shaft rotation. Electric motors can be operated

by direct current (DC) sources, such as batteries, motor vehicles either rectifiers, or by

alternating current (AC) sources, such as power grids, inverters or electrical generators. In

that case, we can introduce the analogy between a motor and a transformer that is a motor

that is like a transformer with a secondary moving. The primary that does not move is called

the stator, and the secondary that moves is called the rotor. The type of engine used

worldwide with a higher percentage is the three-phase induction engine.

Motors that work by rotating motion by receiving power as current flows are normal

within a magnetic field. Nevertheless, there are a wide range of types of motors, including

those that work by linear motion. Motors are generally classified according to the type of

drive power (source) used and classified either as alternating current (AC) or direct current

(DC).Three-phase electrical power is a common method of alternating electricity generation,

transmission and distribution of electrical power. It is a type of polyphase system and is the

most common technique used by electrical grids worldwide for transferring power. It is also

used to fuel big engines and other heavy loads. Where a polyphase electrical supply is

available, the three-phase (or polyphase) AC induction engine is widely used, particularly for

higher-powered motors. The phase variations between the three phases of the polyphase

electrical supply generate a spinning electromagnetic field in the engine.

1.0 Functions of a Three-phase Transformer and Motor in a Mechanical Room of a

Commercial Building

Transformers and motors are the key driving force for industrial, commercial, and

residential appliances. We can’t even imagine an industry or any commercial operation that

would run without transporters and motors. In commercial buildings and industries all types

of rotational or linear force, torque, movement, etc are applied by motors[ CITATION Ste09 \l

2057 ]. Commercial are getting automated day by day, hence, the use of motors are

increasing with the same pace. The power supply to any medium or large-scale industry is

supplied via transformer as the utilities tend to deliver at higher grid voltage. Motors are the

total portion of the power consumed in any industry.

(a) Functions of a Three-phase Transformer in a Mechanical Room of a Commercial

Building

Transformer is considered as an extended version of an inductor. Three separate

single-phase transformers can be used for three-phase power, or all three phases can be

connected to a single poly-phase transformer. In this case, there is a relation between the

magnetic circuits, the centre containing a three-phase flux stream. It links the three main

windings together and ties the three secondary windings together. The most popular links are

three separate single-phase transformers can be used for three-phase power, or all three

phases can be connected to a single poly-phase transformer. In this case, there is a relation

between the magnetic circuits, the centre containing a three-phase flux stream. It links the

three main windings together and ties the three secondary windings together[ CITATION

Mik18 \l 2057 ]. The most popular links are ∆-∆, Y-Y, Y-∆, and ∆-Y. The Earth contact point

is normally the centre point of a Y winding when a winding is connected to earth (grounded).

(b) Functions of a Three-phase Motor in a Mechanical Room of a Commercial Building

Since motor can be operated by both direct current (DC) sources, such as batteries and

alternating current (AC) sources, such as power grids, inverters or electrical generators, it has

two case of three-phase with both carrying closer functions. For three-phase AC induction

motors, through the electromagnetic induction, (the time changing and reversing rotating

magnetic field induces a reversing and a time changing) current in the conductor in the rotor,

produces a workhorse power that is so vital for big industries and commercial buildings.

Producing up to about 670 horsepower (500kW) in output. Very large induction motors are

capable of tens of thousands of kW in output that can be used for wind-tunnel drives,

overland conveyor systems and pipeline compressors. Other types of motors like three-phase

AC synchronous motors are highly valued because their power factor is much better than that

of induction motors, making them preferred for very high power applications.

2.0 List the Main Components for Electrical and Mechanical of a Motor and a

Transformer

There are various basic electrical and electronic components which are commonly

found in both transformer and motor. In similarity for these devices, their components are

used to build the circuit, which are classified into two categories such as passive components

and active components.

(a) Components for Electrical and Mechanical of a Transformer

A transformer is an electrical device consisting of two wire coils, which are connected

by an iron core. It provides the much-needed ability to easily change the current and voltage

levels. The transformer's main function is to increase (step-up) or decrease (step-down) AC

voltages. In secondary coil is more winding than the main coil in a step-up transformer. It has

more windings in the main coil than the secondary coil when it comes to a step-down

transformer. This is one of the main reasons that we use AC now in our houses, not direct
ELECRICAL AND TRANSFORMERS 7

current (D.C). Other basic components of a transformer are laminated core, insulating core,

transformer oil, cooling tubes, explosion vent, breather, insulating materials, buchholz tubes,

tap changer, and oil conservator.

(b) Components for Electrical and Mechanical of a Motor

The designs of electric motors can vary considerably, but they usually have three main parts:

a stator, a commutator, and a rotor. Such three components use electromagnetism's enticing

and repulsive forces, allowing the motor to spin continuously as long as it receives a steady

current flow.

i. The commutator: It sits at the one end of coil. It is a metal ring divided into two

halves that reverses the electrical current in the coil each time the coil rotates half a

turn.

ii. The rotor: Usually consisting of copper wire wrapped in a coil around an axle, is

inserted into the stator. The resultant magnetic field moves against the field produced

by the stator as electrical current passes through the coil and makes the axle spin.

iii. The stator: There are two essential parts for each electric motor: one stationary and

one rotating. The stator is the stationary component. Although the configurations

vary, the stator is typically a permanent magnet or a row of magnets lining the

bottom of the motor case, which is generally a round plastic drum.

3.0 Common Causes of Electric Motors Failure

It is estimates that 92% of the electric motor failures occur at the start up, and most of

these failures happen due to low resistance. All electric motors have their predetermined life

span ranging from 30, 000 to 40,000 hours. However, this is dependent on proper

maintenance. These main causes are:

(i) Low Resistance: It is caused by an excessive current flow within the motor windings,

exceeding the designed current which the motor is able to carry safely and efficiently. It can

be as a result of low supply voltage, in respond to this, the motor draws in more current in

attempt to maintain its torque

(ii) Contamination: Dirt from dust and chemical is another leading factor causing failure in

motors. When unwanted substance find their way inside the motor can cause dent bearing

raceways and balls, which leads to high levels of wearing and vibrating.

(iii) Over-Heating: It is caused by poor power quality, or a high temperature operating

environment.

(iv) Vibration: It is often caused by the motor being positioned on an uneven or unstable

surface. Still, vibration can be caused by underlying issue with the motor, such as

misalignment, bearing, or corrosion.

(v) Electrical overload: Also known as over-current, it is as a result of excessive current flow

within the motor winding, exceeding the design current which the motor is able to carry

efficiently and safely.

4.0 Detailed Step by Step Process to a Failed Motor

Also known as root cause methodology, it focuses on the stress that acted upon the

failed component. The key steps in root cause methodology are:

Failure mode: The form, manifestation, or arrangement of the failure for example turns –to-

turn.

(i) Failure pattern: How the failure is configured for instance asymmetrical or symmetrical

(ii) Appearance: Assessment of the failed component, the whole engine, and the operating

system. Care should be taken to inspect all parts of the motor for damage, corrosion,

moisture, cracks, or other pressure signs.

(iii) Application: A close assessment of the engine work and the characteristics of these load

types.

(iv) Maintenance history: A check out the work done to keep the engine and equipment in

good working condition.

5.0 Interpreting Rating Label of a Transformer and Motor

The nameplate is normally located on all produced transformers and electric motors.

Though understanding the rating label can be cumbersome, it is essential to take into

consideration. Some of the displayed information on the rating label are: Voltage, type,

efficiency, kW or Horse power, frequency, phase, duty, current, power factor, full-load speed,

maximum ambient temperature, altitude, frame, enclosure, bearings and NEMA/Letter

cord/design letter/service factor.

6.0 Interpreting warning label on the motor and transformer

We recognize that it is of utmost importance to keep people safe and conscious by

using signs and labels when there are risks around them. Proper identification and warning is

crucial to keeping people alert and secure on all pad-mounted and pole-mounted

transformers. In addition, NEMA highly recommends transformer labels on any transformer

in a public area. For many years, most transformer labels made of materials with a high

degree of chemical abrasion and heat resistance can withstand harsh conditions (Herman,

2017). It is recommended that you browse the transformer and motor tag range below and

keep people alert to the hazards.

7.0 Protective Devices Related to Motors and Transformers

The importance of effective transformer and control transformer protection cannot be

over emphasized. After motors, transformers are typically the second most common
ELECRICAL AND TRANSFORMERS 10

application where proper over current protection is required and utilized to provide the

necessary protection to facilitates, electrical systems, equipment, and most importantly

electrical workers and other involved personnel. A device used to protect equipment,

components and devices, machinery, in electrical and electronic circuits, against over current,

short circuit, and earth fault, is called protective devices. Some of these protective devices

related to transformers and motors are

 MCB – Miniature Circuit Breaker

 ELCB – Earth Leakage Circuit Breaker

 ELCB and MCB

 Earthing or Grounding

 Fuse wire or Fuse

8.0 Other Components Connected to Motor and Transformer

In the circuits of almost all peripherals, there are various important basic electrical

components commonly found. Such instruments are the key components of electrical and

electronic circuits. Some of these components are: resistor, capacitor, diode/LED, integrated

circuit, ralays, switch, and inductor.

9.0 Preventive Motor Maintenance

There are simple routine and maintenance checks for three phase motor which can

help a long life to a motor. Maintenance programmes aim to prevent critical breakdowns

rather than repairing them. Some of these simple checks and routine to transformers and

motors are:

(i) Check oil level in bearings

(ii)Technician to examine the starter switch, tighten loose connection and fuses
ELECRICAL AND TRANSFORMERS 11

(iii)Clean motor of any oil or dust.

(iv)Check oil rings turn with shaft.

(v) Visually check for oil and grease from bearings.

(vi) Check and replace brushes that are more than half worn

(vii) Check grease in ball or roller bearings.

10.0 Electrical Troubleshooting

The best and rewarding aspect of working with devices is determining what is

actually going on and making a sound decision on the correct course of action. A successful

troubleshooting a complex piece of equipment gives a technician a tremendous sense of

relieve and satisfaction. The best approach to determining the issue with the motor the

technician should apply these guideline for a successful troubleshooting.

(i) Gather the information – Get to know the logic of the device in relation to its operation

(ii) Understand the malfunction – Identify what portion of the process is operating

incorrectly.

(iii)Identify which parameters need to be evaluated – Get familiarized with the part in terms

of its part it plays in operation.

(iv)Identify the source of the problem – Use the technician to isolate components and

evaluate circuit parameters to isolate circuit group as he/she deals with a complicated circuit.

(v)Repair the component – Perform the required repairs to the circuits.

(vi) Verify the repair– Ensure the equipment is operation as it is designed. Perform enough

tests to ensure it operates right

(vi)Perform root cause analysis- Use the knowledge gained throughout the troubleshooting

process in determining what could have possibly have caused the component to fail.
ELECRICAL AND TRANSFORMERS 12

References

Georgilakis, P.S. (2009). Electrical transformers design and construction technology:

technology and engineering. Spotlight on Modern Transformer Design,1, 3-4.

El-Hawary, M. E. (2008). Introduction to electrical power systems. Piscataway, NJ:

Hoboken, New Jersey : IEEE Press.

Herman, S. L. (2009). Electricity and controls for hvac-r(9781435484276). Delmar Cengage

Learning.

Herman, S. L. (2017). Understanding motor controls. Boston, MA, USA: Cengage Learning.

Mikail, R. (2018). Fundamentals of Electric Motors and Transformers. Dhaka: Bangladesh

University of Engineering and Technology.