Motor Control

Motor Control SystemsCore Applications

BY: CELESTINO COLE

04/12/2023 2

1. Definition of motor controllers.2. Different types of motor controllers.3. How control circuit interacts with different

components to met specific requirements.4. The use of motor control for energy

savings.

At the end of the presentation we will know the following:

cole.c/motor_control

04/12/2023cole.c/motor_control 3

ELECTRIC MOTORELECTRIC MOTOR- is an electrical machine that converts electrical energy to mechanical energy in order to produce work.

Modern civilization is incomplete without electric motors !!!


A motor controller is a device or group of devices that serves to govern in some predetermined manner the performance of an electric motor.

DEFINITION

A motor controller includes a manual or automatic means for starting and stopping the motor, selecting forward or reverse rotation, selecting and regulating the speed, regulating or limiting the torque, and protecting against overloads and faults.


MOTOR CONTROL SYSTEMS

REQUIREMENTS

i.e. conveyor, lift, pump, fan

and others

MOTOR CONTROLCORE APPLICATIONS

CONVENTIONAL METHOD USING

ELECTROMECHANICAL COMPONENTS AND

SYSTEMS

ADVANCE METHOD USING PLC, MICROCONTROLLER,

SCADA, REMOTE CONTROLLER


Full voltage starter is the most common type of motor starter where the motor is connected directly across the line.

FULL VOLTAGE STARTER

When started this way the starting current will reach as high as 600% of its full load current.

This method of starting is used for motors 10 HP and below.


FULL VOLTAGE STARTER:NON-REVERSING

RUN SIMULATION

Commonly known as across the line method of starting. This type of starter is used when controlling motor in one direction.

* When the start button is pressed the contactor is activated closing the main contact M and causes the motor to run.

* The auxiliary contact M that is connected in parallel with the “start” pushbutton will hold the whole rung remain activated whenever the pushbutton will return into its original position after pressing.


FULL VOLTAGE STARTER:NON-REVERSING


VARIATION Depending upon the requirements every circuit may vary

depending upon the application requirements.

For example:

The NC auxiliary contact of the pressure switch can be connected in series with the standard DOL starter in order to automatically off the motor once the set value for pressure is reach.


FULL VOLTAGE STARTER:REVERSING

RUN SIMULATION

Commonly known as forward-reverse method of starting. This type of starter is used when controlling motor in two directions.

* The key for reversing the direction of the motor is that the lines that supplies the other contactor (R) L1and L3 is interchanged.

* The 2 normally closed contacts that are connected in series in forward and reverse rung respectively are called electrical interlocking. This is to prevent simultaneous activation of the 2 rungs that might cause serious damage to the equipment if happens.

* When the forward F contactor is activated the motor will put into forward direction.


EXAMPLES OF MOTOR THAT USED REVERSING CONTROL


VARIATION FOR REVERSING CIRCUIT

The NC contact from the limit switch can be connected in series with the UP branch of the reversing circuit to automatically stop the motor once it reach the desired level.

Similarly the NC contact from the limit switch can be connected in series with the DOWN branch of the reversing circuit to automatically stop the motor once it reach the desired level.

LS

LS


Reduced voltage starter is a type of motor starter wherein the effect of the starting inrush current is suppressed. This can be accomplish by the used of sequential switching from the initial to the final state. Once the motor has come up to some fraction of its full-load speed the starter switches to full voltage at the motor terminal.

REDUCED VOLTAGE STARTER

Full voltage starting of motors can produce objectionable voltage flicker, mechanical stress to gear boxes or belt drive systems and create pressure surges or water hammer in pumping applications.

Starting a motor at reduced voltage can help reduce or overcome these problems. Reduced voltage is typically used for motors 10 HP or more.


Wye-Delta is an electromechanical way of reducing the voltage applied (58%) during starting. This can be accomplish by connecting the motor at Y first during starting (3-5sec) and changing it to DELTA thereafter.

In 3-phase system:

REDUCED VOLTAGE STARTING:WYE-DELTA STARTER

𝑉 𝑦=𝑉 𝑙𝑖𝑛𝑒

√ 3

𝑉 𝑙𝑖𝑛𝑒

𝑉 𝑙𝑖𝑛𝑒

√3



RUN SIMULATION



T6

CIRCUIT OPERATION IN WYE-DELTA STARTING


VARIATION OFWYE-DELTA STARTER

float

NC auxiliary contact for float control relay can be installed in series with the main contactor to automatically control the pump operation.

The pushbuttons are replaced with selector switch since the latched circuit cannot be automatically activated once deactivated.


REDUCED VOLTAGE STARTING:AUTOTRANSFORMER

Once the start button is pressed the contacts from S and Y contactor will be close, thus reducing the starting current at the desired level.

After 3-5 seconds these contacts will open followed by the closing of contacts from contactor R.


REDUCED VOLTAGE STARTING:AUTOTRANSFORMER

Autotransformer starting method is commonly used in large submersible pump motors. Just like wye-delta the effect of starting inrush current is suppressed.

BENEFITS:1. Submersible pumps

commonly have 3 leads out, making it unfit for wye-delta starting.

2. If there are 6 leads out submersible pump available then it is economically impractical to use wye-delta since it follows that an additional three conductors are needed to power up the motor.

3. Other applications where the starting voltage is to be reduced lower than 58% then autotransformer can be used since wye-delta starting is fixed at 58%.


PART WINDING

PWS can be accomplished by first energizing the half of the motor coil for at most 3 seconds then followed by the energization of the overall coil.

Unlike the wye-delta starting that is used for accelerating the motor or provide reduced torque, PWS on the other hand mainly used to minimized voltage drop that keeps the nearby lights free from flickering.

RUN SIMULATION


SOFT STARTERSoft starter is a solid state device used with AC electric motors to temporarily reduce the load and torque of the motor during startup. This reduces the mechanical stress on the motor and shaft, as well as the electrodynamic stresses on the attached power cables and electrical distribution network, extending the lifespan of the system.


SOFTSTARTER

TYPICAL POWER CIRCUIT


SOFTSTARTER

TYPICAL POWER CIRCUIT

Auxiliary SCR output contact 13-14 is used for controlling the start/stop function directly wired from the control circuit to the soft starter.

Auxiliary SCR output contact 23-24 is activated when the ramp up time has elapsed causing the by-pass contactor to be activated.


COMPARISON

DIRECT ON LINE WYE- DELTA SOFT STARTER


VARIABLE FREQUENCY DRIVE

A variable-frequency drive (VFD) is a solid state device for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor.

Where:

= synchronous speed (RPM)f = frequency (Hz)P = number of poles



VFD system



VFD can be controlled by many ways such as:

• Button or attached HMI

• Potentiometer for remote control operation

• Discrete input from PLC or other remote controlled relay

• PID signal from transmitters and transducers

• Computer ports thru RS-485


VFD CONTROL

VFD is controlled manually by keypad or attached HMI.


VFD CONTROL:DIRECT MANUAL EXAMPLE

CAN SEAMER TIN COIL CUTTING LINE


VFD CONTROL:REMOTE CONTROL

For remote control manual operation:

A separate remote control unit using toggle switch, pushbutton and potentiometer can be installed to control the operation of the VFD.

For automated operation:

A remote control unit and feedback control using transmitters and transducers forming close loop system is installed to control the operation of the VFD.


VFD WITH REMOTE CONTROL

Discrete output from PLC can be connected directly to VFD.


APPLICATION EXAMPLE FOR VFD WITH REMOTE CONTROL

BOILER CONTROL ROOM

DEVICE LOCATION


VFD CONTROL: AUTOMATED CLOSE LOOP SYSTEM

AUTOMATING VFD SYSTEM CAN BE USED FOR ENERGY SAVING PURPOSES

--- 4-20 mA or 0-10 VDC


VFD CONTROL: AUTOMATED CLOSE LOOP SYSTEM

Temperature sensor

Temperature controllerPLC

-analogue signal feedback: 4-20 mA or 0-10 VDC

HMI

motor

The VFD can be activated manually thru HMI or from PLC if the motor operation is dependent on the other parts of the industrial processes.

C O L

E

The function of the analogue feedback signal is to keep the speed of the motor at the set value.


MOTOR CONTROL FOR ENERGY SAVING APPLICATIONS:AIR BLAST FREEZER

In air-blast freezer where the fan are used to induced cool air to the products.

Once the cool air are uniformly distributed all throughout the products, the temperature will tend to go down until the temperature will reach into the saturated level (e.g. -35 degree C ).

When the temperature will go beyond its required value, it is already useless as far as the requirement is concern.

The fan that are continuously running at full speed once the temperature requirement is met manifests waste of energy.

Solution:

The temperature sensor will detect that the temperature level. The sensor will send feedback to the VFD thru temperature

controller. The VFD now will regulate the speed of the motor so as to met

the required temperature.


MOTOR CONTROL FOR ENERGY SAVING APPLICATIONS:GRAIN DRYER

In grain dryer the fan are used to induced hot air to the products.

The size of the drying bin is fixed and the fan is designed for that size.

Sometime the volume of the production is relatively lower than the drying capacity.

If the fan is operated at full speed it could result into substandard products.

The conventional solution for this problem is the installation of valve in the drying bin that would served as a passage to the excess hot air.

The evacuated hot air manifests waste of energy.

Solution:

The temperature sensor will detect that the temperature level. The sensor will send feedback to the VFD thru temperature

controller. The VFD now will regulate the speed of the motor so as to met

the required temperature.


HOW VFD REDUCES ENERGY CONSUMPTION

AFFINITY LAW OF CENTRIFUGAL LOADS:

P2/P1 = (f2/f1)3

P2= (f2/f1)3 X P1

From the formula it is clear that an 80% speed reduction of the motor driving centrifugal loads such as pumps and fans can make 50% reduction of electrical consumption.

REMEMBER THAT:

Nsyn = (120 x f ) / P

f = (P x Nsyn ) / 120

SAMPLE


THANK YOU VERY MUCH…

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Motor Control