SELECTION OF INDUCTION MOTORS FOR 
PETROLEUM PRODUCT PUMPS AND 
ITS ECONOMICS 
 
 
by 
Pelpolage Pujitha Chaminda Dissanayake 
 
 
 
This thesis was submitted to the department of Electrical Engineering in 
partial fulfillment of the requirements for the Degree of 
Master of Engineering 
 
 
Supervised By : Dr. J P Karunadasa 
 
 
Department of Electrical Engineering 
University of Moratuwa 
Sri Lanka 
 
2004 
 
82489 
 
 
 
  
Abstract 
 
This research thesis outlines the necessary guidelines and methods to select the most 
suitable Induction Motor for a Petroleum Product Pump, having a variable load 
pattern. Conventional way to select a motor for a particular pump is based on the 
assumption that the motor operates nearly at its rated power continuously throughout 
the full operating period. But, Petroleum Product Pumps, which are connected to 
Product Gantries, have variable loads varying from zero to rated power (i.e. most of 
time low efficiency under load condition with high losses) as demanded by Gantries. 
This scenario opens the door to carry out studies to investigate the available and the 
new possibilities to select a proper size motor without. exceeding its mechanical and 
thermal withstanding capabilities for the same load pattern (say, Loading Induction 
Motor beyond its Name-Plate ratings). 
 
First, the existing pump drive systems at Ceylon Petroleum Corporation were studied 
together with their present performance and working environment to gather better 
ideas. Simultaneously, a survey of Induction Motors available in the 
national/international markets was done considering their types, performances, 
specifications and costs. 
 
Standards were important for this task and all relevant standards were collected from 
various Standards Institutions, locally and internationally. 
 
After the basic studies, two product pumps (which were connected to 50HP motor) at 
Kolonnawa Terminal, feeding both Diesel and Kerosene products to Gantry "A" and 
"B" were selected to collect operating data. The available data were analysed by 
using the method (developed) of Equivalent Continuous Motor Size as the case 
study. 
 
Finally, the results (i.e. Equivalent Continuous Motor Size) were compared with the 
available 
  
motors to secure Economical and Technical advantages. 
Ultimately, the most suitable Squirrel Cage Induction Motor for a Petroleum Product 
Pump 
for a given Loading Pattern and Working Environment was decided. 
Declaration 
I hereby declare that the work presented in this report is my own work and not has been 
submitted earlier or concurrently for any other degree. 
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1 certify that this work was supervised by me and the above declaration is true. 
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Acknowledgement 
/ 
I express my sincere gratitude to Dr. J P Karunadasa for all the encouragement, guidance and 
support given throughout my Engineering Carrier to make this task a success. 
I also would like to convey my gratitude to Mr. Wimal Amarasinghe, Engineering Manager, 
Mr Anthony Martin, Senior Deputy Engineering Manager, all Engineers and my Foreman 
Mr Gemunu Neelagolla with his Staff in Engineering Department of Ceylon Petroleum 
Corporation, Kolonnawa Terminal for the support given at various stages of this project. 
Finally a big thanks goes to my parents and two sisters for finding me free time and free mind 
taking my responsibilities to do the research. 
"*W. • . -.; 
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Figure 1.1 
Figure 1.2 
Figure 1.3 
Figure 2.1 
Figure 2.2 
Figure 2.3 
Figure 2 4 
Figure 2.5 
Figure 2.6 
Figure 2.7 
Figure 2.8 
Figure 3.1 
Figure 3.2 
Figure 3.3 
Figure 3.4 
Figure 3.5 
Figure 3.6 
Figure 3.7 
Figure 3.8 
Figure 3.9 
List of Figures 
Typical torque-speed curve for a standard AC induction motor 
Typical torque-speed curves for Design A, B, C, and D motors 
Characterises curves of Selected Pump for case study 
Typical torque-speed characteristics of centrifugal pump 
Actual motor output variation of a typical day 
Three-phase squirrel cage induction motors Derating factor due to 
.I 
Unbalanced Voltage 
Typical Power Factor vs Load 
Voltage Flicker Curve 
Insulation Life vs Temperature 
Different types of Motor Losses and its Percentage 
Typical Motor Efficiency vs Load 
Voltage variation of a typical day 
Frequency variation of a typical day 
Starting and continuous No Load Current of 50HP motor 
IV 
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Starting and continuous No Load Active & Reactive Power of 50HP motor 41 
Starting and continuous Full Load Current of 50HP motor 42 
Starting and continuous Full Load Active & Reactive Power of 50HP motor 42 
Current variation of a Diesel-Pump motor 43 
Active and Reactive Input Power variation of a Diesel-Pump motor 
Active Energy consumption of Diesel-Pump motor 
43 
44 
Figure 3.10 Power Factor variation of a Diesel-Pump motor _ . 44 
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Figure 3.11 Actual and Equivalent Output Power variation of a Diesel-Pump motor 45 
Figure 3 12 Current variation of a Kerosene-Pump motor 46 
Figure 3. 13 Active and Reactive Input Power variation of a Kerosene-Pump motor 46 
Figure 3.14 Active Energy consumption of Kerosene-Pump motor 47 
Figure 3.15 Power Factor variation of a Kerosene-Pump motor 47 
Figure 3.16 Actual and Equivalent Output Power variation of a Kerosene-Pump motor 48 
v 
List of Tables & Charts 
Page 
Table 1.1 Details of Gantry Pumps in Ceylon Petroleum Corporation 2 
Table 1.2 Average Induction Motor Prices for both Standard types and 
Explosion Proof types 3 
Table 1.3 Typical values of Locked Rotor & Breakdown Torque of 
induction motors 5 
Table 1.4 Index ofProtection numbers and relevant definitions 8 
Table 1.5 Performances of different types NEMA design mo;ors 10 
Table 1.6 Different types of motor Insulation Classes II 
Table 1.7 Temperature Codes and corresponding Maximum Surface 
Temperatures 13 
Table 1.8 Suitable types ofProtections for different Zones 14 
Table 1.9 Name-Plate data of Selected Motor for case study 15 
Table 2.1 Effects of variation of Voltage and Frequency 24 
Table 2.2 Class oflnsulation and corresponding Temperature Rise 32 
Chart 2.1 Technical Guides for Motor Selection 38 
Table 3.1 Weekly variation of Optimum Equivalent Continuous Motor Sizes 49 
411111l...'••: 
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I 
Declaration 
Abstract 
Acknowledgement 
List of Figures 
List ofTables & Charts 
Contents 
Chapter 1 
INTRODUCTION 
1.1 Background of Research 
Contents 
1.2 Induction Motors installed in Ceylon Petroleum Corporation 
1.3 Induction Motors availability and their Performances 
1.3 .1 Name-Plate Data 
1.4 General Standards of Electric Motors 
1.4.1 Most Common IEC Standards 
1.4.2 NEMA Electrical Design Standards 
l 5 Standards for Hazardous Area Motors 
1.5.1 Hazardous Zone (or Division) Classification 
1.5.2 Classification of Hazardous Materials 
1.5.3 Temperature Class 
1.5.4 Types of Protection 
1.6 Tools and Equipments used to collect Data 
Chapter 2 
SELECTION OF MOTORS 
2.1 Pump Characteristics and Load Pattern 
2. 1. 1 Running Characteristics 
2 2 Selection Methods of Equivalent Motor 
2.2.1 Temperature Behaviour oflnduction Motor 
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2 .2.2 Selection of a Continuous Duty Motor for Variable Loads 22 
2.3 Electrical Distribution System and Motor Characteristics 
2.3.1 Voltage and Frequency 
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24 
2.3.2 Rated Current 
2.3.3 Power Factor 
2.3.4 Voltage Flicker 
2.3.5 Starting Methods 
2.3.6 Direction of Rotation 
2.3.7 Accessories required for Gantry Motors 
2.4 Physical and Environmental Considerations 
2.4.1 Usual Service Conditions 
2.4.2 Service Conditions Applicable to Petroleum Industry 
2.4.3 Motor Enclosure 
2.4.4 Mounting 
2.4.5 Noise level and Vibration 
2.4.6 Core, Winding and Rotor 
2.4.7 Insulation 
2.4.8 Duty 
2.4.9 Service Factor and Overload Capability 
2.5 Efficiency and Economic Considerations 
2.5.1 Capital Costs 
2.5.2 Energy Costs 
2.5.3 Motor Efficiency 
2.5.4 Efficiency and Motor Sizing 
Chapter 3 
CASE STUDY AND RESULTS 
f 
3.1 Equivalent Continuous Motor Size calculation for Diesel Pump 
3.2 Equivalent Continuous Motor Size calculation for Kerosene Pump 
3.3 Results 
Chapter 4 
CO~CLUSION 
4.1 Future Considerations and Project Expansions 
REFERENCES 
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