-SQA-SCOTTISH QUALIFICATIONS AUTHORITY
HIGHER NATIONAL UNIT SPECIFICATION
GENERAL INFORMATION
-Unit Number-
2460897
-Superclass-
XJ
-Title-
ELECTRICAL NETWORKS
-----------------------------------------DESCRIPTIONGENERAL COMPETENCE FOR UNIT:
Applying network
measurement and reduction techniques to electrical networks.
theorems,
OUTCOMES
1.
apply reduction techniques to evaluate an electrical network;
2.
apply network theorems to solve network problems;
3.
use measurement techniques to analyse electrical networks.
CREDIT VALUE:
1 HN Credit
ACCESS STATEMENT: Access to this unit is at the discretion of the centre.
However, It would be beneficial if the candidate possessed NC module:
NC module:
2160010 Electrical Fundamentals
2160030 Single Phase AC
HN Unit:
2460877 Single Phase AC Networks
----------------------------------------For further information contact: Committee and Administration Unit, SQA,
Hanover House, 24 Douglas Street, Glasgow G2 7NQ.
Additional copies of this unit may be purchased from SQA (Sales and Despatch
section). At the time of publication, the cost is £1.50 (minimum order £5.00).
Unit No. 2460897
Continuation
HIGHER NATIONAL UNIT SPECIFICATION
STATEMENT OF STANDARDS
UNIT NUMBER:
2460897
UNIT TITLE:
ELECTRICAL NETWORKS
Acceptable performance in this unit will be the satisfactory achievement of the
standards set out in this part of the specification. All sections of the statement of
standards are mandatory and cannot be altered without reference to SQA.
OUTCOME
1.
APPLY REDUCTION TECHNIQUES
ELECTRICAL NETWORK
TO
EVALUATE
AN
PERFORMANCE CRITERIA
(a)
(b)
(c)
(d)
The network is correctly reduced to its equivalent total resistance
using reduction techniques.
The total network current, apparent, active and reactive power are
calculated correctly.
Current division rule is applied to the network to calculate branch
currents and power dissipated correctly.
Voltage division rule is applied to the network to calculate
individual potential differences correctly.
RANGE STATEMENT
network: voltage source; series and parallel impedances.
EVIDENCE REQUIREMENTS
Written evidence is required to show that the candidate can perform calculations
of total impedance, total current, active, reactive and apparent power, branch
currents and potential differences for an electrical network comprising a source
and a minimum of five impedances as detailed in performance criteria (a) to (d).
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Unit No. 2460897
Continuation
OUTCOME
2.
APPLY NETWORK
PROBLEMS
THEOREMS
TO
SOLVE
NETWORK
PERFORMANCE CRITERIA
(a)
(b)
(c)
(d)
An ac network is solved correctly using star/delta and delta/star
transformations.
A dc network is solved correctly using Kirkchhoff’s Laws.
An ac network is solved correctly using a Thevenin equivalent
circuit.
An ac network is solved correctly using a Norton equivalent circuit.
RANGE STATEMENT
ac network: voltage source and impedances.
dc network: voltage sources; resistors.
EVIDENCE REQUIREMENTS
Written evidence is required to show that the candidate can apply network
theorems to solve networks, as detailed in performance criteria (a), (c) and (d) for
one voltage source and five impedances in a series/parallel configuration. Two
voltage sources and three resistors in a T configuration are required for PC (b).
OUTCOME
3.
USE
MEASUREMENT
ELECTRICAL NETWORKS
TECHNIQUES
TO
ANALYSE
PERFORMANCE CRITERIA
(a)
(b)
(c)
Ohm’s Law is verified by accurately measuring and recording
voltages and currents in a dc circuit containing one voltage source
and a resistance.
Kirchhoff’s laws are verified by accurately measuring and
recording currents and voltages in a dc network.
Thevenin and Norton equivalent circuits are calculated and drawn
correctly from measurements taken in an ac network.
RANGE STATEMENT
The range for this outcome is fully expressed in the performance criteria.
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Unit No. 2460897
Continuation
EVIDENCE REQUIREMENTS
Written evidence in the form of a report is required to show that the candidate
can verify Ohm’s law in a dc circuit as detailed in performance criterion (a).
Written evidence, in the form of a report is also required to demonstrate that the
candidate can verify Kirchhoff’s Laws from test results as detailed in PC (b).
Written evidence in the form of a report including calculations and equivalent
circuits should be provided as evidence for performance criterion (c).
Measurements should be taken from an ac network comprising a voltage source
and a minimum of four impedances for performance criterion (c).
MERIT To gain a pass in this unit, a candidate must meet the standards set out
in the outcomes, performance criteria, range statements and evidence
requirements.
To achieve a merit in this unit, a candidate must demonstrate a superior or more
sophisticated level of performance. This may be demonstrated by:
(i)
(ii)
measurement techniques;
applying reduction techniques and network theorems to unfamiliar
problems.
-----------------------------------------
ASSESSMENT
In order to achieve this unit, candidates are required to present sufficient
evidence that they have met all the performance criteria for each outcome within
the range specified. Details of these requirements are given for each outcome.
The assessment instruments used should follow the general guidance offered by
the SQA assessment model and an integrative approach to assessment is
encouraged. (See references at the end of support notes).
Accurate records should be made of the assessment instruments used showing
how evidence is generated for each outcome and giving marking schemes
and/or checklists, etc. Records of candidates’ achievements should be kept.
These records will be available for external verification.
SPECIAL NEEDS
Proposals to modify outcomes, range statements or agreed assessment
arrangements should be discussed in the first place with the external verifier.
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Unit No. 2460897
Continuation
 Copyright SQA 1997
Please note that this publication may be reproduced in whole or in part for
educational purposes provided that:
(i)
(ii)
no profit is derived from the reproduction;
if reproduced in part, the source is acknowledged.
5
Unit No. 2460897
Continuation
HIGHER NATIONAL UNIT SPECIFICATION
SUPPORT NOTES
UNIT NUMBER:
2460897
UNIT TITLE:
ELECTRICAL NETWORKS
SUPPORT NOTES: This part of the unit specification is offered as guidance.
None of the sections of the support notes is mandatory.
NOTIONAL DESIGN LENGTH: SQA allocates a notional design length to a unit
on the basis of time estimated for achievement of the stated standards by a
candidate whose starting point is as described in the access statement. The
notional design length for this unit is 40 hours. The use of notional design length
for programme design and timetabling is advisory only.
PURPOSE The unit is designed to provide core knowledge to support HN units
in HND Electronic Engineering, Electrical Engineering and Telecommunications.
CONTENT/CONTEXT
Outcome 1
PC (a) It is recommended that the candidate will utilise the formulae for both
series and parallel impedances in reducing the network to the equivalent total
impedance.
Relevant formulae:
Series Zeq = Z1 + Z2 ......... Zn
Parallel 1/Zeq = 1/Z1 + 1/Z2 .... 1/Zn
PC (b) It is recommended that the candidate will cover Active power VICos and
12R, Reactive Power VISin and I2X and apparent power VI and I2Z.
PC(c) Current division should be restricted to a division of current for two
impedances.
Outcome 2
It is recommended that:
PC(a) the candidate will cover both star/delta and delta/star transformations
hence a suitable network would be an unbalanced Wheatstone Bridge.
PC(b) in using Kirchhoff’s Laws for solving currents and potential differences in
the network care should be taken to ensure that the student develops an
understanding of the laws in ascertaining the direction of current flow and points
of high and low potential in the network.
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Unit No. 2460897
Continuation
PC(c) the impedance characteristics of ideal voltage and current generators are
outlined in the development of the equivalent circuits. In addition the relationship
between the Thevenin and Norton equivalent circuits should be demonstrated.
Outcome 3
It is recommended that V = KI should be verified and the resistance obtained
from the slope of the graph. A computer simulation package can be used for
PC(b) or as an addition to the laboratory exercise to confirm the measurements.
APPROACHES TO GENERATING EVIDENCE The unit should be taught in a
classroom environment where access to a laboratory and computers with
suitable simulation packages are available.
ASSESSMENT PROCEDURES
Outcome 1
Structured question
Outcome 2
Structured questions
Outcome 3
Reports on the practical or computer simulation tests.
PROGRESSION This unit provides basic knowledge to support the specialist
areas in Electrical Engineering.
A support pack for this is available from SQA. Please call our Sales and
Despatch section on 0141 242 2168 to check availability and costs. Quote
product code C086.
REFERENCES
1.
2.
3.
4.
Guide to unit writing.
For a fuller discussion on assessment issues, please refer to SQA’s
Guide to Assessment.
Information for centres on SQA’s operating procedures is contained in
SQA’s Guide to Procedures.
For details of other SQA publications, please consult SQA’s publications
list.
 Copyright SQA 1997
Please note that this publication may be reproduced in whole or in part for
educational purposes provided that:
(i)
(ii)
no profit is derived from the reproduction;
if reproduced in part, the source is acknowledged.
7