SAQA All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.
SOUTH AFRICAN QUALIFICATIONS AUTHORITY 
REGISTERED UNIT STANDARD THAT HAS PASSED THE END DATE: 

Demonstrate knowledge of power system voltage control 
SAQA US ID UNIT STANDARD TITLE
242768  Demonstrate knowledge of power system voltage control 
ORIGINATOR
SGB Power Plant Operations 
PRIMARY OR DELEGATED QUALITY ASSURANCE FUNCTIONARY
-  
FIELD SUBFIELD
Field 06 - Manufacturing, Engineering and Technology Engineering and Related Design 
ABET BAND UNIT STANDARD TYPE PRE-2009 NQF LEVEL NQF LEVEL CREDITS
Undefined  Regular  Level 6  Level TBA: Pre-2009 was L6  4 
REGISTRATION STATUS REGISTRATION START DATE REGISTRATION END DATE SAQA DECISION NUMBER
Passed the End Date -
Status was "Reregistered" 		 2018-07-01  2023-06-30  SAQA 06120/18 
LAST DATE FOR ENROLMENT LAST DATE FOR ACHIEVEMENT
2024-06-30   2027-06-30  

In all of the tables in this document, both the pre-2009 NQF Level and the NQF Level is shown. In the text (purpose statements, qualification rules, etc), any references to NQF Levels are to the pre-2009 levels unless specifically stated otherwise.  

This unit standard does not replace any other unit standard and is not replaced by any other unit standard. 

PURPOSE OF THE UNIT STANDARD 
A person credited with this unit standard understands the principles of voltage control on the electrical network, the system's need for reactive power (VARs) and how VARs are generated and/or absorbed by the various components of the power system. 

LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING 
It is assumed that learners are already competent in:
  • Communication and Mathematical Literacy at NQF Level 5.
  • Appropriate mechanical and electrical knowledge at NQF Level 5. 
    		•

    UNIT STANDARD RANGE 
    N/A 

    Specific Outcomes and Assessment Criteria: 

    SPECIFIC OUTCOME 1 
    Explain MVAr supply and demand. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Types of power produced at the generators and the difference in electrical. equipment work functions are explained according to specified requirements. 

    ASSESSMENT CRITERION 2 
    Curves for power are compared and explained according to requirements. 
    ASSESSMENT CRITERION RANGE 
    Purely inductive circuit and power in a purely capacitive circuit.
     

    ASSESSMENT CRITERION 3 
    The difference between VARs are explained according to requirements. 
    ASSESSMENT CRITERION RANGE 
    Negative and Positive VARs.
     

    ASSESSMENT CRITERION 4 
    Power system components that supply or demand VARs on the system are described according to requirements. 

    ASSESSMENT CRITERION 5 
    The concept of components is described with examples. 
    ASSESSMENT CRITERION RANGE 
    Components to "compensate" for others.
     

    ASSESSMENT CRITERION 6 
    Production of MW and MVAr in an electric generator is explained according to requirements. 

    ASSESSMENT CRITERION 7 
    The function and response of an Automatic Voltage Regulator (AVR) to an increase or decrease in MVAr demand on the system are described according to requirements. 

    ASSESSMENT CRITERION 8 
    Voltage characteristics to drive MVAr through the system are explained according to requirements. 

    ASSESSMENT CRITERION 9 
    The function of a synchronous condenser and a static VAR compensator are described according to requirements. 

    SPECIFIC OUTCOME 2 
    Describe the effect of line loadings on VARs and voltage. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    MVAr source or load reasons are explained according to requirements. 

    ASSESSMENT CRITERION 2 
    The effect of current flow on voltage drop is described according to requirements. 

    ASSESSMENT CRITERION 3 
    The voltage drop resulting from the flow of MW is explained according to requirements. 

    ASSESSMENT CRITERION 4 
    Events that can have a profound effect on MVAr flows and voltage level are described according to requirements. 

    ASSESSMENT CRITERION 5 
    Transmission line requirements with respect to MVAr when the MW loading is increased are explained with examples. 

    ASSESSMENT CRITERION 6 
    Typical transfer limit curve (PV) and the significance of the knee of the curve is sketched and explained according to requirements. 

    ASSESSMENT CRITERION 7 
    The industry limit is described according to NERC requirements. 
    ASSESSMENT CRITERION RANGE 
    Limit for percent voltage change following any single contingency and system conditions and events that may lead to a voltage collapse.
     

    SPECIFIC OUTCOME 3 
    Explain characteristics and effects of line Surge Impedance Loading (SIL). 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    The significance of a line's Surge Impedance Loading (SIL) is explained according to requirements. 

    ASSESSMENT CRITERION 2 
    The importance of having adequate MVAr sources located at intermediate points in the network is explained according to requirements. 

    ASSESSMENT CRITERION 3 
    The voltage profile along a transmission line is explained according to requirements. 
    ASSESSMENT CRITERION RANGE 
    Operating at, above or below SIL, with voltage at both ends fixed.
     

    ASSESSMENT CRITERION 4 
    Reasons for MVAr supply drop off is explained according to requirements. 
    ASSESSMENT CRITERION RANGE 
    From a line's capacitance drop off sharply at loadings above SIL.
     

    ASSESSMENT CRITERION 5 
    Typical loading levels for electrical lines in percentage of SIL are explained according to requirements. 

    SPECIFIC OUTCOME 4 
    Explain generating plant voltage control equipment and methods. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    The importance for system operators to prepare in advance for voltage emergencies is explained according to requirements. 

    ASSESSMENT CRITERION 2 
    Methods of adjusting voltage and or VAR supply at the generating units are described according to requirements. 

    ASSESSMENT CRITERION 3 
    Reasons why VAR setpoints must be raised or lowered in unison to effect a net change in voltage and VAR supply are explained according to requirements. 

    ASSESSMENT CRITERION 4 
    Typical generator capability curve sketched and the lagging or leading VAR limitations are described according to requirements. 

    ASSESSMENT CRITERION 5 
    Function and operation of excitation limiters is explained according to requirements. 
    ASSESSMENT CRITERION RANGE 
    Maximum and minimum limiters on generating units.
     

    ASSESSMENT CRITERION 6 
    Power system components that allow operators to adjust voltage and VAR supply at locations other than generating plants are explained according to requirements. 

    SPECIFIC OUTCOME 5 
    Explain transmission voltage control equipment and methods. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Reactive overload capability of generators, synchronous condensers, and static VAR compensators are described according to requirements. 

    ASSESSMENT CRITERION 2 
    Typical applications for shunt reactor and capacitor banks on the transmission system are explained according to requirements. 

    ASSESSMENT CRITERION 3 
    Assistance of series capacitors in voltage control is explained according to requirements. 

    ASSESSMENT CRITERION 4 
    Function and operation of Load Tap Changing Transformers (LTCs) in providing voltage correction on the transmission and distribution systems are explained according to requirements. 

    ASSESSMENT CRITERION 5 
    The importance of operator actions in implementing voltage control is explained according to requirements. 
    ASSESSMENT CRITERION RANGE 
    Curtailing economy transfers, bringing on local generation, bringing on reactive sources ahead of the morning load rise, removing lines during light load.
     


    UNIT STANDARD ACCREDITATION AND MODERATION OPTIONS 
  • Anyone assessing a learner or moderating the assessment of a learner against this unit standard must be registered as an assessor with the relevant Education, Training, Quality, Assurance (ETQA) Body, or with an ETQA that has a Memorandum of Understanding with the relevant ETQA.
  • Any institution offering learning that will enable the achievement of this unit standard must be accredited as a provider with the relevant Education, Training, Quality, Assurance (ETQA) Body, or with an ETQA that has a Memorandum of Understanding with the relevant ETQA.
  • Assessment and moderation of assessment will be overseen by the relevant Education, Training, Quality, Assurance (ETQA) Body, or by an ETQA that has a Memorandum of Understanding with the relevant ETQA, according to the ETQA's policies and guidelines for assessment and moderation.
  • Moderation must include both internal and external moderation of assessments at exit points of the Qualification, unless ETQA policies specify otherwise. Moderation should also encompass achievement of the competence described both in the Unit Standards.
  • Anyone wishing to be assessed against this unit standard may apply to be assessed by any assessment agency, assessor or provider institution that is accredited by the relevant ETQA. 
    		•

    UNIT STANDARD ESSENTIAL EMBEDDED KNOWLEDGE 
    Principles of voltage control on the electrical network. 

    UNIT STANDARD DEVELOPMENTAL OUTCOME 
    N/A 

    UNIT STANDARD LINKAGES 
    N/A 


    Critical Cross-field Outcomes (CCFO): 

    UNIT STANDARD CCFO IDENTIFYING 
    Solve problems. 

    UNIT STANDARD CCFO COLLECTING 
    Collect, organise and critically evaluate information. 

    UNIT STANDARD CCFO COMMUNICATING 
    Communicate effectively using visual, mathematical and language skills in the modes of oral and written procedures. 

    UNIT STANDARD CCFO SCIENCE 
    Use science and technology effectively and critically. Show responsibility towards the environment and health of others. 

    UNIT STANDARD CCFO DEMONSTRATING 
    Demonstrate an understanding of the world as a set of related systems. 

    UNIT STANDARD CCFO CONTRIBUTING 
    Contribute to the full personal development of each learner and the social and economic development of the society
    at large, by making it the underlying intention of any programme of learning to make an individual aware of the importance of:
  • Reflect on and exploring a variety of strategies to learn more effectively.
  • Participate as responsible citizens in the life of local, national and global communities.
  • Be culturally and aesthetically sensitive across a range of social contexts.
  • Explore education and career opportunities.
  • Develop entrepreneurial opportunities. 
    		•

    UNIT STANDARD ASSESSOR CRITERIA 
    N/A 

    REREGISTRATION HISTORY 
    As per the SAQA Board decision/s at that time, this unit standard was Reregistered in 2012; 2015. 

    UNIT STANDARD NOTES 
    N/A 

    QUALIFICATIONS UTILISING THIS UNIT STANDARD: 
      ID QUALIFICATION TITLE PRE-2009 NQF LEVEL NQF LEVEL STATUS END DATE PRIMARY OR DELEGATED QA FUNCTIONARY
    Elective  57693   National Diploma: Electrical Network Power Dispatch Controlling  Level 5  NQF Level 05  Passed the End Date -
    Status was "Reregistered"     		 2023-06-30  EWSETA 


    PROVIDERS CURRENTLY ACCREDITED TO OFFER THIS UNIT STANDARD: 
    This information shows the current accreditations (i.e. those not past their accreditation end dates), and is the most complete record available to SAQA as of today. Some Primary or Delegated Quality Assurance Functionaries have a lag in their recording systems for provider accreditation, in turn leading to a lag in notifying SAQA of all the providers that they have accredited to offer qualifications and unit standards, as well as any extensions to accreditation end dates. The relevant Primary or Delegated Quality Assurance Functionary should be notified if a record appears to be missing from here.
     
    NONE 


    All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.