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Linear Control Systems Lab Manual

This lab manual document provides instructions for implementing closed loop speed control of a DC servo motor. The objective is to learn closed loop motor speed control techniques. The components include a DC servo trainer, potentiometers, summing amplifier, pre-amplifier, motor driver amplifier, tacho unit, DC power supply, techometer, servo motor and function generator. The procedure involves arranging the components, setting the selector switch, adjusting the potentiometer to obtain half maximum speed, attaching an electronic brake and recording RPM and error voltage at each setting with and without feedback loop. Observations show that motor speed decreases and error increases as load increases, demonstrating closed loop speed control.

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97 views3 pages

Linear Control Systems Lab Manual

This lab manual document provides instructions for implementing closed loop speed control of a DC servo motor. The objective is to learn closed loop motor speed control techniques. The components include a DC servo trainer, potentiometers, summing amplifier, pre-amplifier, motor driver amplifier, tacho unit, DC power supply, techometer, servo motor and function generator. The procedure involves arranging the components, setting the selector switch, adjusting the potentiometer to obtain half maximum speed, attaching an electronic brake and recording RPM and error voltage at each setting with and without feedback loop. Observations show that motor speed decreases and error increases as load increases, demonstrating closed loop speed control.

Uploaded by

Rohaan a.k.a Honey
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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Linear Control Systems lab Manual

Lab # 8

Implementation of Closed Loop Motor Speed Control of DC Servo


Motor

Name: Raja Rohaan Abdullah

Semester: 6th

Section: A

Mis id: 30558

Department of Electrical Engineering

Submitted to: Engr. Saqib Riaz


Objective: To know the closed loop Motor speed control technique

Components: DC Servo Trainer (ED-4400-B) U-158 Potentiometer U-151 Dual Attenuator U-


152 Summing Amplifier U-153 Pre-Amplifier (20 db) U-154 Motor Driver Amplifier (10 watts)
U-155 Tacho Am Unit U-156 DC Power Supply U-157 Potentiometer (Ref) (1KOhm to 10
KOhm) U-158 Potentiometer (Motor Coupling) (1KOhm to 10 KOhm) U-159 Techometer (FS
4000 RPM) U-161 Servo Motor U-162 Function Generator U-163 Magnet Brake

Theory: When a motor is used as a source of mechanical force, the motor is required to provide
constant speed regardless of the change in load. A closed loop speed control system is a self-
regulating system in which the measured speed of the motor is compared to the preset value to
produce an error output. The detected error voltage is then amplified and fed back to the control
circuit to compensate the difference between the actual and preset speed. The self correcting
process continues until the detected error voltage becomes zero. At this point the actual speed of
the motor is equal to the preset speed

Procedure:

• Referring to figure arrange the required modules and connect them together. • Set the selector
switch of summing amplifier U-152 to ‘a’.

• Set AAT-2 of the U-151 to ‘10’ to prevent Tacho output from entering the system. Set AAT-1
to ‘5’.

• Turn the power of U-156 on.

• Adjust U-157 to obtain about one half of the maximum speed. This is same as setting for 2500
RPM on U-159 meter.

• Attach an electronic brake U-163 with the brake’s setting increased by one notch at a time;
record the RPM reading at each setting.

• Measure the error voltage at each brake setting. (There is no feedback at this point. Therefore,
the error voltage will vary only when the preset speed is changed to a different value).

• Set ATT-2 of U-151 to ‘5’. Adjust U-157 to obtain the same speed as in step 5 (around 2500
RPM).

• Measure the Tacho output and error voltage at different brake points.

• Compute the results between steps 3-7 and step 8-9. Notice that the loop was closed for steps 8-
9

Observations:
We observed that when we increased the load at the input, the speed of the motor decreased. It
means that the error value will increase as we increase the load.

Calculation

No load Output speed error


1 0 2500 0
2 1 2300 200
3 2 2200 300
4 3 2100 400
5 5 2000 500

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