lab 6 kawalan motor

8/10/2019 lab 6 kawalan motor

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EXPERIMENT : AUTO TRANSFORMER STARTER

1. AIM

To provide knowledge in Auto Transformer Starter

2. OBJECTIVES

To familiarize the student with:

1.1 Control circuit and main circuit for Auto Transformer Starter

1.2 Operation in starting AC motor with Auto Transformer Starter.

1.3 Control equipment for Electrical Motor Control

3. EQUIPMENT

Bil

1. 3 phase Contactor 3 unit

2. Thermal Overload Relay (TOR) 1 unit

3. Push button Start 1 unit

4. Push button Stop 1 unit

5. Miniature Circuit Breaker (MCB) 1 unit6. Molded Case Circuit Breaker (MCCB) 1 unit

7. Pilot lamp 2 unit

8. 3 phase AC motor (3/4 ~ 3 hp) 1 unit

9. Timer (TDR) 1 unit

10. Relay 1 unit

11. Cable Necessary


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4. THEORY

Auto transformer starter

This starter produces highefficiency and have the option to be adjusted to obtain the

necessary torque and in accordance with the system. It veryefficiency starter but the

disadvantage is it very high cost to setup control panel starter.

It can improved torque ratio is achieved and starting current is typically 3 times Full Load

Current , depending on the voltage taps selected. Typically it have taps at 50%,65% and

80% voltage.

During start-up, the motor is connected to theauto transformers tapping. This means that

the motor starts up with a reduced voltage and a correspondingly low current.

What is auto transformer starter?

Theauto transformer reduces the current in the mains supply line further and in

accordance with its ratio. The technique for connecting an AutoTransformer starter is via

magnetic contactor and connect the motor to taps by mean of the contactor.

When motor accelerate to full speed, the tap of contactor was open and disconnecting

motor fromtransformer and other contactor close to connecting the motor to the supply.

When the motor has almost reached its rated torque, the starconnection on the

transformer is opened.
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ADVANTAGES OF AUTO TRANSFORMER STARTER:

a ) On the 65% tapping the line current is approximately equal tp that of a Star-Delta

starter, however, at the time of switching from reduced voltage to the full supply voltage,

the motor is not disconnected so that the second peak is very much reduced since the

transformer is converted into reactance for a short time

b ) It is possible to vary the tapping from 65% to 80% or even up to 90% of the supply

voltage in order to ensure that the motor starts satisfactorily.

DISADVANTAGES OF AUTO TRANSFORMER STARTER:

a ) One of its great disadvantages is the limitation of its operation frequency. It is always

necessary to know the operation frequency in order to determine a suitably rated auto-

transformer.

b ) The compensating switch is much more expensive than a Star-Delta starter due to the

auto-transformer.

c ) Due to the size of the auto-transformer starter, much larger control panels are required

which increases the price.


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5. EXPERIMENT PROCEDURE

5.1 EXERCISE 1 : CONTROL CIRCUIT

5.1.1 Will make a connection to the control circuit as shown in Figure 1 (a) or

1 (b)

5.1.2 Taking incoming voltage from 1 to 3 lines (R or Y or B) on a single

phase.

5.1.3 After that I'll connect circuit line is back to neutral (N) using a black

cable.

5.1.4 Experiments will be done on this circuit by making the circuit

connections to the power supply control circuit for testing purposes.

5.1.5 Please refer to the operation of the circuit is

Figure 1(a): control circuit of Auto Transformer Starter


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5.2 EXERCISE 2 : MAIN CIRCUIT

5.2.1 Main circuit connections as shown in Figure 2.

5.2.2 Supply coming to this track is from the 3 phase 415V (R, Y, B, and N)

5.2.3 I will make a connection from the earth (E) to the 3-phase motor.

5.2.4 Then I will make a series of experiments on the circuit is armed with 3-

phase supply is to make full operation on the main circuit and control

circuit AC Motor

5.2.5 Please refer to this operation Auto Transformer Starter

Figure 2: Main circuit of Auto Transformer Starter


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6. DISCUSSION

6.1 Briefly explain the result of this experiment

After the supply was connected to the motor control circuit , press the start

button is pressed will start , after which the current flows through the coil C4

and will get current supply circuit and the contacts N / O C4 will turn into N /

C and timer coil will get electricity . Three main contact S4 will be closed ( N

/ C ) and will be connected to a timer and supply will be doubled. Timer

contacts N / O will turn into a camera and timer coil will get electricity , touch

timer increased N / C will open . With this auto transformer is connected in a

star shape . And voltage to the motor . In addition, the contact is closed N / C

contacts will switch to open N / O to N / C . Therefore , C3 supply and thus

completing the circuit and the motor will rotate .

6.2 Briefly explain the operation of Auto transformer starter.

When the start button is pressed, coils CR, TR, SC1, and SC2 energize.

When the SC1 and SC2 load contacts close, the motor is connected to the

center tap of the open delta auto transformer. Since the transformers have beencenter tapped, the motor is connected to half of the line voltage. A basic

schematic diagram of this connection is shown in Ill. 2.

The normally closed SC1 and SC2 auxiliary contacts connected in

series with the R coil open to provide interlock and prevent the R contactor

from energizing as long as SC1 or SC2 is energized.

After some time, TR timer reaches the end of its timing sequence and

the two timed TR contacts change position. The normally closed TR contact

connected in series with coils SC1 and SC2 opens and de-energizes these

contactors. This causes all SC1 and SC2 load contacts to open and disconnect

the autotransformer from the line. The normally closed SC1 and SC2 auxiliary

contacts connected in series with R coil reclose.

When the normally open TR contact connected in series with R coil

closes, the R contactor energizes and closes all R load contacts. This connectsthe motor directly to the power line.


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The normally closed R auxiliary contact connected in series with coils

SC1 and SC2 opens to provide interlock. The motor will continue to run until

the stop button is pressed or an overload occurs

6.3 Expline function of equipment list.

3 phase Contactor

The top three contacts switch the respective phases of the incoming 3-

phase AC power, typically at least 480 Volts for motors 1 horsepower or

greater. The lowest contact is an "auxiliary" contact which has a current rating

much lower than that of the large motor power contacts, but is actuated by the

same armature as the power contacts. The auxiliary contact is often used in a

relay logic circuit, or for some other part of the motor control scheme,

typically switching 120 Volt AC power instead of the motor voltage. One

contactor may have several auxiliary contacts, either normally-open or

normally-closed, if required.

Thermal Overload Relay (TOR)

Thermal overload relays are 3 pole. The motor current flows through

their bimetals (1 per phase) which are indirectly heated.Under the effect of

the heating, the bimetals bend, cause the relay to trip and the position of the

auxiliary contacts to change.The relay setting range is graduated in amps. In

compliance withinternational and national standards, the setting current is the

motor nominal current and not the tripping current (no tripping at 1.05 x

setting current, tripping at 1.2 x setting current). The tripping curves (cold or

warm starting, 3 phases and 2 phases) are shown in the main catalog. The

relays are built to be self protecting in theevent of an overload until the short

circuit protection device is activated


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Push button Start

Contains a pair of existing open contacts (normally open, NO) which

willclosed when the Button is pressed. When ready to open contacts closed,

current will flowing in the circuit.

Push button Stop

Contains a pair of normally closed contacts (normally closed, NC),

which will be open when Button is pressed. When ready to close the contacts

open, it will be decided the flow of electric current.

Miniature Circuit Breaker (MCB)

Miniature circuit breakers or MCBs are used to replace fuses that

protect individual pieces of electrical equipment and the circuits which supply

them with power

Molded Case Circuit Breaker (MCCB)

Molded case circuit breakers are designed to provide circuit protection

for low voltage distribution systems. They protect connected devices against

overloads and/or short circuits

Pilot lamp

A pilot lamp is a light that illuminates under specific conditions, most

commonly when an electrical circuit is energized. It may also be known as an

indicator lamp or pilot light, although this should not be confused with a small

flame kept burning in a gas appliance to provide a source for ignition when the

appliance is turned on. Pilot lamps are used in a wide variety of settings and in

some cases are required by law for safety reasons


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3 phase AC motor (3/4 ~ 3 hp)

Induction motor or asynchronous motor is a type of AC motor where

power is supplied to the rotor by electromagnetic induction. Electric motor for

rotating the magnetic force applied between a stationary electromagnet called

the stator with a rotating elektrimagnet called the rotor.

Timer (TDR)

The TDR series of electronic relays is a processor based control thatcan have many different functions. The operation of the TDR is determined at

the time of manufacture, based on the firmware loaded into the relay.

Special functions (X) that are unique to a customers specific application are

available by contacting the factory.

Relay

A relayis anelectrically operatedswitch. Many relays use

anelectromagnet to mechanically operate a switch, but other operating

principles are also used, such assolid-state relays.Relays are used where it is

necessary to control a circuit by a low-power signal (with complete electrical

isolation between control and controlled circuits), or where several circuits

must be controlled by one signal. The first relays were used in long

distancetelegraph circuits as amplifiers: they repeated the signal coming in

from one circuit and re-transmitted it on another circuit. Relays were used

extensively in telephone exchanges and early computers to perform logical

operations.

A type of relay that can handle the high power required to directly

control an electric motor or other loads is called acontactor.Solid-state

relays control power circuits with nomoving parts, instead using a

semiconductor device to perform switching. Relays with calibrated operating
http://en.wikipedia.org/wiki/Electrichttp://en.wikipedia.org/wiki/Switchhttp://en.wikipedia.org/wiki/Electromagnethttp://en.wikipedia.org/wiki/Solid-state_relayhttp://en.wikipedia.org/wiki/Electrical_telegraphhttp://en.wikipedia.org/wiki/Contactorhttp://en.wikipedia.org/wiki/Solid-state_relayhttp://en.wikipedia.org/wiki/Solid-state_relayhttp://en.wikipedia.org/wiki/Moving_partshttp://en.wikipedia.org/wiki/Moving_partshttp://en.wikipedia.org/wiki/Solid-state_relayhttp://en.wikipedia.org/wiki/Solid-state_relayhttp://en.wikipedia.org/wiki/Contactorhttp://en.wikipedia.org/wiki/Electrical_telegraphhttp://en.wikipedia.org/wiki/Solid-state_relayhttp://en.wikipedia.org/wiki/Electromagnethttp://en.wikipedia.org/wiki/Switchhttp://en.wikipedia.org/wiki/Electric


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characteristics and sometimes multiple operating coils are used to protect

electrical circuits from overload or fault, in modern electric power systems

these functions are performed by digital instruments still called "protective

relays".

Cable

Cable has a function that acts as a media transimisi to accelerate the

delivery of the message

6.4 What the advantages and disadvantages of this starter compared to the other

type of starter (Dierect On Line Starter, Star-Delta Starter, ETC)

ADVANTAGES OF AUTO TRANSFORMER STARTER:

On the 65% tapping the line current is approximately equal tp that of a

Star-Delta starter, however, at the time of switching from reduced

voltage to the full supply voltage, the motor is not disconnected so that

the second peak is very much reduced since the transformer is

converted into reactance for a short time

It is possible to vary the tapping from 65% to 80% or even up to 90%

of the supply voltage in order to ensure that the motor starts

satisfactorily.

DISADVANTAGES OF AUTO TRANSFORMER STARTER:

One of its great disadvantages is the limitation of its operation

frequency. It is always necessary to know the operation frequency in

order to determine a suitably rated auto-transformer.

The compensating switch is much more expensive than a Star-Delta

starter due to the auto-transformer.

Due to the size of the auto-transformer starter, much larger control

panels are required which increases the price.
http://en.wikipedia.org/wiki/Protective_relayhttp://en.wikipedia.org/wiki/Protective_relayhttp://en.wikipedia.org/wiki/Protective_relayhttp://en.wikipedia.org/wiki/Protective_relay


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ADVANTAGES OF DOL STARTER

Most Economical and Cheapest Starter

Simple to establish, operate and maintain

Simple Control Circuitry

Easy to understand and troubleshoot.

It provides 100% torque at the time of starting.

Only one set of cable is required from starter to motor.

Motor is connected in delta at motor terminals.

DISADVANTAGES OF DOL STARTER

It does not reduce the starting current of the motor.

High Starting Current: Very High Starting Current (Typically 6 to 8

times the FLC of the motor).

Mechanically Harsh: Thermal Stress on the motor, thereby reducing its

life.

Voltage Dip: There is a big voltage dip in the electrical installation

because of high in-rush current affecting other customers connected to

the same lines and therefore not suitable for higher size squirrel cage

motors

High starting Torque: Unnecessary high starting torque, even when not

required by the load, thereby increased mechanical stress on the

mechanical systems such as rotor shaft, bearings, gearbox, coupling,

chain drive, connected equipments, etc. leading to premature failure

and plant downtimes.

ADVANTAGES OF STAR DELTA STARTER:

a ) Star-Delta starters are widely used due to their relatively low price.

b ) There are no limits to the number of times they can be operated.

c ) The components require very little space.


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d ) The starting current is reduced to approximately one-third.

DISADVANTAGES OF STAR DELTA STARTER:

a ) The starter can only be applied to motors where the six leads or terminals

can be accessed.

b ) The supply voltage must be the same as the rated motor voltage for Delta

connection.

c ) Because the starting current is reduced to approximately one-third of the

rated current, the starting torque is also reduced to one-third.

d ) If the motor does not reach at least 90% of its rated speed at the time of

switching from Star to Delta the current peak will be as high as in a D.O.L.

start, thus causing harmful effects to the contacts of the contactors and the

connection system brings no advantage to the electrical system.

The advantages/disadvantages of different types of motor starters like

DOL, star/ delta, korndorfer, primary resistance/reactance, shunt capacitance,

slip ring, vfd, vsd, auto transformer etc.

DOL (simple start up but reflect to high voltage drop, high starting

current, low starting period duration)less power saving. star/delta decrease the

starting current to 1/3 but required many relays for control change between

start connection then to delta.

Auto transformer used for MV application by connect less voltage on

motor during start up then change to nominal voltage on motor terminals after

start up where reflect to decrease the starting current and decrease the voltage

drop but increase the starting duration (very expensive where required 3

MVCB one for motor and one for primary of auto and one for secondary of

auto).


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VSD or VFD used for application where its worked with inlet guide

van or valve (variable load) to make power saving. Capacitor used to avoid the

voltage drop during motor start up but may cause many problems like

resonance.


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CONCLUSION

The end of the experiment on the autotransformer starter, I can learn about the controlcircuit and main circuit for Auto Transformer Starter. With that I also can find more detail

about the operation to start the AC motor with Auto Transformer Starter. And I can also learn

about the tools used to Electric Motor Control. Other than that, I can also see myself

operations performed in the circuit autotransformer starter. With that I also can learn how

Connection to a fully autotransformer circuit.


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Reference

1. http://iitg.vlab.co.in/?sub=61&brch=168&sim=941&cnt=1

2. http://en.wikipedia.org/wiki/Relay

3. http://www.industrial-electronics.com/lab_manual_electr_41.html

4. http://top10electrical.blogspot.com/2014/03/advantages-and-disadvantages-of-

auto.html

5. http://www.softstarter.org/advantages-disadvantages-of-different-motor-starters-

526301.html

6.
http://iitg.vlab.co.in/?sub=61&brch=168&sim=941&cnt=1http://iitg.vlab.co.in/?sub=61&brch=168&sim=941&cnt=1http://en.wikipedia.org/wiki/Relayhttp://en.wikipedia.org/wiki/Relayhttp://www.industrial-electronics.com/lab_manual_electr_41.htmlhttp://www.industrial-electronics.com/lab_manual_electr_41.htmlhttp://top10electrical.blogspot.com/2014/03/advantages-and-disadvantages-of-auto.htmlhttp://top10electrical.blogspot.com/2014/03/advantages-and-disadvantages-of-auto.htmlhttp://top10electrical.blogspot.com/2014/03/advantages-and-disadvantages-of-auto.htmlhttp://top10electrical.blogspot.com/2014/03/advantages-and-disadvantages-of-auto.htmlhttp://top10electrical.blogspot.com/2014/03/advantages-and-disadvantages-of-auto.htmlhttp://www.softstarter.org/advantages-disadvantages-of-different-motor-starters-526301.htmlhttp://www.softstarter.org/advantages-disadvantages-of-different-motor-starters-526301.htmlhttp://www.softstarter.org/advantages-disadvantages-of-different-motor-starters-526301.htmlhttp://www.softstarter.org/advantages-disadvantages-of-different-motor-starters-526301.htmlhttp://www.softstarter.org/advantages-disadvantages-of-different-motor-starters-526301.htmlhttp://www.softstarter.org/advantages-disadvantages-of-different-motor-starters-526301.htmlhttp://www.softstarter.org/advantages-disadvantages-of-different-motor-starters-526301.htmlhttp://top10electrical.blogspot.com/2014/03/advantages-and-disadvantages-of-auto.htmlhttp://top10electrical.blogspot.com/2014/03/advantages-and-disadvantages-of-auto.htmlhttp://www.industrial-electronics.com/lab_manual_electr_41.htmlhttp://en.wikipedia.org/wiki/Relayhttp://iitg.vlab.co.in/?sub=61&brch=168&sim=941&cnt=1


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Before testing

Time test,blue lamp is ON


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Trip lamp

lab 6 kawalan motor

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