MODULE DETAILS

Module 18: Network Protection

Nominal duration: 5 weeks (60 hours total time commitment)

This time commitment includes the preparation reading, attendance at each webinar (1 hour plus 15-30 minutes for discussion), and the time necessary to complete the assignments and further study.

MODULE PURPOSE

This module discusses the protection of transmission and distribution systems in the electric supply industry and imparts the skills required to select appropriate protection devices for various types of systems, carry out the testing and commissioning of protection systems, and verify the settings.

PRE-REQUISITE MODULE(S)

Module 17: Power Supply System Equipment and Installations

ASSESSMENT STRATEGY

To evaluate the achievement of the learning outcomes; written assignments, group projects and practical exercises are set.

SUMMARY OF LEARNING OUTCOMES

1.   Explain the schemes for protection of distribution feeders

2.   Examine the schemes for protection of transmission feeders

3.   Apply busbar protection to switchgear

4.   Commission network protection systems

Learning Outcome 1

Explain the schemes for protection of distribution feeders

Assessment Criteria

1.1

Identify and describe the faults in overhead lines used in transmission and distribution

1.2

Identify and describe the use of fuses and compare the different types of fuses commonly used in networks

1.3

Describe:

(a)   the procedure for planning the protection         devices for distribution feeders using over-        current and earth fault relays, and;

(b)   the rules for setting and coordinating these         protective devices.

1.4

Explain:

(a)   the correlation between the system earthing         practices followed;

(b)   the choice of earth fault protection device, and;

(c)   how to overcome the hazard of broken HV         conductors by sensitive protection.

Learning Outcome 2

Examine the schemes for protection of transmission feeders

Assessment Criteria

2.1

Examine and discuss the application of unit protection in transmission feeders (pilot wire protection) and other forms of comparison such as phase comparators

2.2

Describe and explain:

(a)   the application of distance protection to         transmission feeders, and;

(b)   safeguarding against incorrect operations due to         arc resistance and power swings

2.3

Outline the process required to enhance a distance protection scheme by the use of power line carrier communication (PLC) and other equivalent digital communication methods

2.4

Describe the application of directional protections in transmission systems  

Learning Outcome 3

Apply busbar protection to switchgear

Assessment Criteria

3.1

Examine and discuss the application of unit protection to busbars and compare available alternatives.

3.2

Discuss the application of numerical relays to large transmission substations and the resulting flexibility

3.3

Configure a busbar protection system for a substation with multiple busbars and disconnectors (for circuit switching) clearly outlining the problem areas and methods for overcoming spurious trips by check-zone approach.

3.4

Review and assess the alternative methods of busbar protection specially applicable for metal clad MV switchgear such as frame earth type, blocking type and optical sensing and their pros and cons

Learning Outcome 4

Commission network protection systems

Assessment Criteria

4.1

Explain the need for testing of current and voltage transformers and the procedures to be used to carry out the test

4.2

Examine and discuss the procedure for testing of over current and earth fault relays

4.3

Describe and assess the requirements for testing complex protection schemes

4.4

Review the use of automated test equipment and prepare a specification for test equipment

4.5

Identify and discuss the procedures for safe commissioning of new protection schemes within existing installations.

Delivery mode

A combination of asynchronous and synchronous e-learning delivery comprising a judicious mix of interactive online web conferencing, simulation (virtual labs) software, remote online labs, online videos, PowerPoint slides, notes, reading and study materials (in PDF, HTML and Word format) accessed through the Moodle Learning Management System (LMS).