# Electrical Technology Grade 12 NSC November 2025 Memo (Eng)

> Grade 12 Electrical Technology memorandum from the NSC November Exam 2025 (English), 17 pages. Read online or download the free PDF.

- Page: https://www.hlayiso.com/library/grade-12-electrical-technology-2025-nsc-november-exam-memorandum/0e3e69c2-c8cb-48d7-92ba-7f433de53597
- Updated: 2026-09-28
- Subject: Electrical Technology
- Grade: Grade 12
- Document type: Memorandum
- Year: 2025
- Exam period: NSC November Exam
- Curriculum: CAPS
- Pages: 17

Breadcrumbs: [Home](https://www.hlayiso.com/) › [Library](https://www.hlayiso.com/library) › [Grade 12](https://www.hlayiso.com/library/grade-12) › [Electrical Technology](https://www.hlayiso.com/library/grade-12/electrical-technology) › [Electrical Technology Grade 12 NSC November 2025 Memo (Eng)](https://www.hlayiso.com/library/grade-12-electrical-technology-2025-nsc-november-exam-memorandum/0e3e69c2-c8cb-48d7-92ba-7f433de53597)

## About this document

Electrical Technology · Grade 12 · NSC November Exam · 2025. Memorandum, 17 pages. Read online or download the PDF.

Read it free online on the page above; download the PDF from there.

## Document text

Text extracted from the PDF. Layout, diagrams and tables may not survive extraction.

### Page 1

NATIONAL
                                 SENIOR CERTIFICATE

                                        GRADE 12

                     ELECTRICAL TECHNOLOGY: POWER SYSTEMS

                                     NOVEMBER 2025

                                 MARKING GUIDELINES

MARKS: 200

                       These marking guidelines consist of 17 pages.

Copyright reserved                                                     Please turn over

### Page 2

Electrical Technology: Power Systems              2                        DBE/November 2025
                                       NSC – Marking Guidelines

 INSTRUCTIONS TO THE MARKERS

 1.        All questions with multiple answers imply that any relevant, acceptable answer
           should be considered.

 2.        Calculations:

           2.1         All calculations must show the formulae.

           2.2         Substitution of values must be done correctly.

           2.3         All answers MUST contain the correct unit to be considered.

           2.4         Alternative methods must be considered, provided that the correct
                       answer is obtained.

           2.5         Where an incorrect answer could be carried over to the next step,
                       the first answer will be deemed incorrect. However, should the
                       incorrect answer be carried over correctly, the marker has to re-
                       calculate the values, using the incorrect answer from the first
                       calculation. If correctly used, the candidate should receive the full
                       marks for subsequent calculations.

 3.        This memorandum is only a guide with model answers. Alternative
           interpretations must be considered and marked on merit. However, this
           principle should be applied consistently throughout the marking session at ALL
           marking centres.

Copyright reserved                                                        Please turn over

### Page 3

Electrical Technology: Power Systems              3               DBE/November 2025
                                       NSC – Marking Guidelines

 QUESTION 1: MULTIPLE-CHOICE QUESTIONS

 1.1       B✓                                                                           (1)

 1.2       B✓                                                                           (1)

 1.3       C✓                                                                           (1)

 1.4       C✓                                                                           (1)

 1.5       D✓                                                                           (1)

 1.6       B✓                                                                           (1)

 1.7       B✓                                                                           (1)

 1.8       A✓                                                                           (1)

 1.9       B✓                                                                           (1)

 1.10      C✓                                                                           (1)

 1.11      B✓                                                                           (1)

 1.12      D✓                                                                           (1)

 1.13      C✓                                                                           (1)

 1.14      C✓                                                                           (1)

 1.15      D✓                                                                           (1)
                                                                                        [15]

Copyright reserved                                                   Please turn over

### Page 4

Electrical Technology: Power Systems              4                         DBE/November 2025
                                       NSC – Marking Guidelines

 QUESTION 2: OCCUPATIONAL HEALTH AND SAFETY

 2.1       Any article or combination of articles assembled, arranged or connected which
           is used for converting any form of energy ✓ to performing work. ✓
                                                   OR
           Any article or combination of articles which is used or intended to be used,
           whether incidental there to or not, for developing, receiving, storing, containing,
           confining, transforming, transmitting, transferring or controlling any form of
           energy.                                                                                 (2)

 2.2       Do not touch the person with bare hands. ✓
           Use a non-conductive material to free the person from the live connection. ✓
           Switch off the supply                                                                   (2)

 2.3       The use/misuse of power tools without adhering to safety protocols. ✓
           The etching of PC boards without following safety procedures. ✓
           Working on a live system without following safety protocol.                             (2)

 2.4       A critical incident is an event that causes grave or severe physical injury to a
           person that requires external emergency services. ✓
           An accident is an event that may cause injury or damage to property (severe
           or not severe). ✓                                                                       (2)

 2.5       It is an unsafe act, because it creates an unsafe condition ✓ (no guard on the
           machine) that is conducted by a person in a manner that may threaten the
           safety ✓ of people in the workshop.                                                     (2)
                                                                                                   [10]

Copyright reserved                                                              Please turn over

### Page 5

Electrical Technology: Power Systems              5                               DBE/November 2025
                                       NSC – Marking Guidelines

 QUESTION 3: RLC CIRCUITS

 3.1       3.1.1       Resonant frequency ✓                                                             (1)

           3.1.2       Quality factor/Q factor ✓                                                        (1)

 3.2       3.2.1                                                  ✓
                       𝑉𝑇 = √𝑉𝑅 2 + (𝑉𝐿 − 𝑉𝐶 )2

                          = √202,162 + (226,82 − 140,18)2         ✓
                          = 219,94 𝑉
                                                                  ✓                                     (3)
           3.2.2          𝑉𝑇
                       𝐼𝑇 =                                       ✓
                           𝑍
                          𝑉𝑇
                       𝑍=
                          𝐼𝑇                                      ✓
                              219,94
                         =
                               3,61
                                                                  ✓
                         = 60,93 𝛺
                                                                                                        (3)
                       OR

                       Alternatively calculate R = 56 Ω and XC = 31,83 Ω, then Z = 64,01 Ω

           3.2.3                𝑉𝑅                                If R is calculated:
                      𝐶𝑜𝑠𝜃 =                        ✓                       𝑅
                                𝑉𝑇                                𝐶𝑜𝑠𝜃 =
                                  𝑉𝑅                                        𝑍
                      𝜃 = 𝐶𝑜𝑠 −1 ( )                                             56
                                  𝑉𝑇                        OR    𝜃 = 𝐶𝑜𝑠 −1 (        )
                                                    ✓                           60,93
                                  202,16
                        = 𝐶𝑜𝑠 −1 (       )                            = 23,21 °
                                  219,94
                                                    ✓
                        = 23,20°                                                                        (3)
           NOTE:               𝑉𝐿 − 𝑉𝐶        may also be used.
                        𝑇𝑎𝑛𝜃 =
                                  𝑉𝑅

           3.2.4               1
                       𝑋𝐶 =                                  ✓
                             2𝜋𝑓𝐶
                       At resonance XL=XC, therefore
                              1
                       𝐶=
                            2𝜋𝑓𝑋𝐶
                                   1                         ✓
                         =
                            2𝜋 × 50 × 62,83
                         = 50,66 𝜇𝐹                          ✓                                          (3)

Copyright reserved                                                                   Please turn over

### Page 6

Electrical Technology: Power Systems               6                       DBE/November 2025
                                        NSC – Marking Guidelines

 3.3
                             ✓
                        VL = 226,82 V

                                                ✓
                                           VT = 219,94 V
            (VL - VC)

                                    θ = 23,20º
                                                       ✓
                               IT = 3,61 A       VR = 202,16 V

                              ✓
                        VC = 140,14 V
           NOTE:
           VL and VC are the TWO primary labels thereafter any TWO correct labels.
           If VL, VC, VR, VT, θ and (VL-VC) are written without values, marks will be awarded
           given there is a distinct difference between the length of the phasors.                 (4)

 3.4       3.4.1                                                 ✓
                        𝐼𝑇 = √𝐼𝑅 2 + (𝐼𝐿 − 𝐼𝐶 )2
                                                                 ✓
                           = √0,52 + (0,9 − 0,2)2
                                                                 ✓
                           = 0,86 𝐴                                                                (3)

           3.4.2               𝑉𝑇                                ✓
                        𝑋𝐶 =
                               𝐼𝐶
                                                                 ✓
                             50
                           =
                             0,2
                           = 250 𝛺                               ✓                                 (3)

 3.5       The circuit is more inductive. ✓ The inductive current IL is greater than the
           capacitive current IC. ✓                                                                (2)

 3.6       When the frequency increases XC decreases ✓ and XL increases ✓ until they
           are both equal ✓ and the circuit will resonate.
           When the frequency increases, IC increases and IL decreases until they are
           both equal and the circuit will resonate.                                               (3)

 3.7       3.7.1        Parallel RLC circuit. ✓ Impedance is maximum ✓ at resonance in a
                        parallel RLC circuit.                                                      (2)

Copyright reserved                                                              Please turn over

### Page 7

Electrical Technology: Power Systems              7                        DBE/November 2025
                                       NSC – Marking Guidelines

           3.7.2            𝑓𝑟                                ✓
                       𝐵𝑊 =
                            𝑄
                       ∴ 𝐵𝑊 = 𝑓2 − 𝑓1                         ✓

                                           7300
                       (9200 − 5400) =                        ✓
                                            𝑄
                                   7300
                         𝑄 =
                              (9200 − 5400)
                                                              ✓
                            = 1,92                                                                 (4)
                                                                                                   [35]

 QUESTION 4: THREE-PHASE AC GENERATION

 4.1       •   Installations costs are very high. ✓
           •   Appliances using three phase power supply are very expensive. ✓
           •   Three-phase power supply voltage is not available everywhere,
           •   Not suitable for most residential applications.                                     (2)

 4.2       A power factor of less than 1 means that the voltage and current waveforms
           are not in phase, ✓ reducing the instantaneous product of the two waveforms ✓
           (effective power delivered).                                                            (2)

 4.3       4.3.1       Delta ✓                                                                     (1)

           4.3.2       400 V ✓                                                                     (1)

           4.3.3
                         VBR                        ✓
                                 ✓                 Rotation

                                       120⁰          VRY ✓
                               120⁰
                                       120⁰

                           ✓
                         VYB

                       NOTE:
                       The following labels will be accepted given the sequence is correct:
                       L1, L2 & L3 , VL1, VL2 & VL3 and R, Y & B
                       If the rotation label is omitted that mark may be awarded to the 120º.      (4)

 4.4       4.4.1       𝑉𝐿 = √3𝑉𝑃𝐻                             ✓

                           = √3 × 220                         ✓
                           = 381,05 𝑉
                                                              ✓                                    (3)

Copyright reserved                                                              Please turn over

### Page 8

Electrical Technology: Power Systems              8                    DBE/November 2025
                                       NSC – Marking Guidelines

           4.4.2        𝑆 = √3 𝑉𝐿 𝐼𝐿                           ✓
                                𝑆
                        𝐼𝐿 =
                               √3 𝑉𝐿
                                 16 000                        ✓
                           =
                               √3 × 381,05
                           = 24,24 𝐴                           ✓                             (3)
           4.4.3     𝑃 = √3𝑉𝐿 𝐼𝐿 𝐶𝑜𝑠𝜃                              ✓

                       = √3 × 381,05 × 24,24 × 𝐶𝑜𝑠(29,54)          ✓
                       = 13 918,75 𝑊
                                                                   ✓
                       = 13,92 𝑘𝑊                                                            (3)
                                                          OR
                     𝑃 = 𝑆𝐶𝑜𝑠𝜃
                       = 16 000 × 𝐶𝑜𝑠(29,54)
                       = 13 920,19 𝑊
                       = 13,92 𝑘𝑊

           4.4.4 𝑄 = √3𝑉𝐿 𝐼𝐿 𝑆𝑖𝑛𝜃                                  ✓

                       = √3 × 381,05 × 24,24 × 𝑆𝑖𝑛(29,54)          ✓
                       = 7887,68 𝑉𝐴𝑟
                                                                   ✓
                       = 7,89 𝑘𝑉𝐴𝑟                                                            (3)
                                                          OR
                     𝑄 2 = 𝑆 2 − 𝑃2

                     𝑄 = √16 0002 − 13 920,192
                       = 7888,49 𝑉𝐴𝑟
                       = 7,89 𝑘𝑉𝐴𝑟

 4.5             𝑃𝑂𝑈𝑇                                      ✓
           𝜂=         × 100
                  𝑃𝐼𝑁
                 3 200                                     ✓
             =         × 100
                 3 450
             = 92,75%                                      ✓
                                                                                             (3)

Copyright reserved                                                        Please turn over

### Page 9

Electrical Technology: Power Systems              9                        DBE/November 2025
                                       NSC – Marking Guidelines

 4.6       4.6.1       Coil A - Current coil. ✓                                                    (1)

           4.6.2       Digital wattmeters:
                       • Eliminates the need for precise mechanical components ✓
                       • Reduces the need for calibration ✓
                       • Can display multiple current, voltage and power readings on one
                          device
                       • Are more accurate (eliminate parallax errors)
                       • Are easier to read than analogue meters                                   (2)

           4.6.3       Coil B is the potential coil connected in parallel with the load to
                       measure voltage. ✓ It is movable with a needle on it and when
                       connected it will create a magnetic field that interacts with the
                       magnetic field on the current coil ✓ and moves/deflects to indicate a
                       reading.                                                                    (2)

 4.7       4.7.1       Higher energy losses ✓
                       Thicker cables are required ✓
                       Larger switchgear is required
                       Higher electricity bills                                                    (2)

           4.7.2       A power factor meter indicates whether a system is more inductive
                       or more capacitive. ✓
                       A power factor meter indicates the ratio of the active/real power to
                       the apparent power of an electrical system.
                       To measure power factor.                                                    (1)

           4.7.3       A load with a low power factor draws more current ✓ than a load with
                       a high power factor because more apparent power is needed to
                       supply the same real power. ✓                                               (2)
                                                                                                   [35]

 QUESTION 5: THREE-PHASE TRANSFORMERS

 5.1       When an alternating voltage is applied to the primary winding, alternating flux
           is set up in the core, ✓ which links with the secondary winding and induces an
           emf ✓ of the same frequency to the secondary.                                           (2)

 5.2       5.2.1       A1 – A3 windings are connected in star configuration. ✓
                       B1 – B3 windings are connected in delta configuration. ✓                    (2)

           5.2.2       An iron core is needed in the construction of a transformer to provide
                       a magnetic field intense enough ✓ to produce the rated voltage ✓ in
                       the windings with a minimum of exciting current. ✓
                                                        OR
                       To strengthen the magnetic coupling in the process of transferring
                       power from the primary to the secondary winding.                            (3)

           5.2.3       It is a Core type. ✓
                       The core is surrounded by the windings. ✓
                       The core has three limbs                                                    (2)

Copyright reserved                                                              Please turn over

### Page 10

Electrical Technology: Power Systems              10                      DBE/November 2025
                                        NSC – Marking Guidelines

           5.2.4       Dry type transformers dissipate heat through a tubular radiator
                       around which air circulates, ✓ keeping the transformer cool.              (1)

 5.3       5.3.1       Voltage rating ✓
                       Current rating
                       Turns ratio
                       Power rating
                       Efficiency                                                                (1)

           5.3.2       It is used as step-down transformers in distribution systems ✓ where
                       a four-wire system (neutral) is required.
                       School, hospital, Industry etc. will be accepted.                         (1)

           5.3.3       The cost of replacing one damaged transformer is less ✓ as
                       compared to replacing the whole three-phase transformer unit. ✓

                       If one transformer (one-phase) becomes faulty, the faulty unit can
                       be removed and replaced without replacing the entire system.              (2)

 5.4      5.4.1       In delta 𝑉𝐿 = 𝑉𝑃𝐻                        ✓
                       ∴ 𝑉𝐿 = 𝑉𝑃𝐻 = 6 600 𝑉                    ✓                                 (2)

          5.4.2        𝑉𝐿 = √3𝑉𝑃𝐻(2)                           ✓
                                   𝑉𝐿
                      𝑉𝑃𝐻(2) =
                                  √3
                                  380                          ✓
                              =
                                  √3
                              = 219, 39 𝑉                      ✓
                                                                                                 (3)

          5.4.3               𝑁1 𝑉𝑃𝐻(1)                        ✓
                      𝑇𝑅 =      =
                              𝑁2 𝑉𝑃𝐻(2)
                               6 600                           ✓
                          =
                              219, 39
                          = 30,08 ∶ 1
                                                               ✓
                          = 30 ∶ 1
                                                                                                 (3)

          5.4.4       𝑉𝑃𝐻(1) 𝐼𝑃𝐻(2)                            ✓
                            =
                      𝑉𝑃𝐻(2) 𝐼𝑃𝐻(1)
                                  𝑉𝑃𝐻(2) 𝐼𝑃𝐻(2)
                      𝐼𝑃𝐻(1) =
                                    𝑉𝑃𝐻(1)
                                   219,92 × 900                ✓
                              =
                                      6 600
                              = 29, 92 𝐴                       ✓                                 (3)
Copyright reserved                                                            Please turn over

### Page 11

Electrical Technology: Power Systems               11                     DBE/November 2025
                                         NSC – Marking Guidelines

 5.5                𝑃𝑂𝑈𝑇                                        ✓
          𝜂=                  × 100
                𝑃𝑂𝑈𝑇 + 𝑙𝑜𝑠𝑠𝑒𝑠
                         𝑃𝑂𝑈𝑇
          𝑙𝑜𝑠𝑠𝑒𝑠 =            − 𝑃𝑂𝑈𝑇
                          𝜂
                         4 500                                  ✓
                     =         − 4 500
                          0,96
                     = 187,50 𝑊                                 ✓
                                                                                                 (3)

 5.6       A conservator is required to allow for the expansion and contraction ✓ of the oil
           during changes of the temperatures with different operating loads ✓ or
           changing of the surrounding air temperature.                                          (2)
                                                                                                 [30]

Copyright reserved                                                            Please turn over

### Page 12

Electrical Technology: Power Systems               12                            DBE/November 2025
                                         NSC – Marking Guidelines

 QUESTION 6: THREE-PHASE MOTORS AND STARTERS

 6.1       Resistance/continuity test of the windings. ✓
           Insulation resistance test between windings. ✓
           Insulation resistance test between windings and earth.                                       (2)
 6.2       The reactive power of a three-phase induction motor is the power used to set
           up and maintain the electromagnetic field in the stator, ✓ without doing any real
           work. ✓                                                                                      (2)

 6.3       6.3.1       A - Locked rotor torque ✓
                          Starting/Start-up torque
                       B - Breakdown torque ✓                                                           (2)

           6.3.2       The slip is minimum at no-load speed. ✓                                          (1)

 6.4       6.4.1            60𝑓                                     ✓
                       𝑛𝑠 =
                             𝑝
                            60 × 50                                 ✓
                          =
                               2
                          = 1500 𝑟/𝑚𝑖𝑛                              ✓                                   (3)

           6.4.2                    ns - nr                         ✓
                       % Slip =             × 100
                                      ns
                                  1 500 - 1 250                     ✓
                                =               × 100
                                      1 500                         ✓
                               = 16,67%                                                                 (3)

 6.5      6.5.1       𝐶𝑜𝑠𝜃 = 𝑝𝑓
                                                                        ✓
                      𝐶𝑜𝑠𝜃 = 0,85
                      𝜃 = 𝐶𝑜𝑠 −1 (0,85)                                 ✓
                        = 31,79°                                        ✓                                (3)

          6.5.2       𝑃 = √3𝑉𝐿 𝐼𝐿 𝐶𝑜𝑠𝜃
                                                                        ✓
                                    𝑃
                      𝑉𝐿 =
                              √3𝐼𝐿 𝐶𝑜𝑠𝜃                                 ✓
                                    4 000
                        =
                             √3 × 6,8 × 0,85                            ✓
                        = 399,55 𝑉                                                                       (3)

          6.5.3       𝑆 = √3 𝑉𝐿 𝐼𝐿                          ✓                    𝑃
                                                                        𝐶𝑜𝑠𝜃 =
                                                            ✓                    𝑆
                        = √3 × 399,55 × 6,8
                                                                              𝑃
                                                                    OR 𝑆 =
                        = 4 705,88 𝑉𝐴                       ✓               𝐶𝑜𝑠𝜃
                        = 4,71 𝑘𝑉𝐴                                          4 000
                                                                        𝑆=
                                                                             0,85
                                                                        𝑆 = 4,71 𝑘𝑉𝐴

Copyright reserved                                                                   Please turn over

### Page 13

Electrical Technology: Power Systems             13                       DBE/November 2025
                                       NSC – Marking Guidelines

          6.5.4       𝑄 = √3𝑉𝐿 𝐼𝐿 𝑆𝑖𝑛𝜃                            ✓

                        = √3 × 399,55 × 6,8 × 𝑆𝑖𝑛(31,79)          ✓
                        = 2479,09 𝑉𝐴𝑅
                                                                  ✓
                        = 2,48 𝑘𝑉𝐴𝑅
                                                                                                  (3)
                                                          OR
                      𝑆 2 = 𝑃2 + 𝑄 2
                      𝑄 = √𝑆 2 − 𝑃2
                         = √4705,882 − 40002
                         = 2478, 97 𝑉𝐴𝑟
                         = 2,48 𝑘𝑉𝐴𝑟

 6.6       6.6.1       MC1N/O ✓
                       Retain / hold-in contact                                                  (1)

           6.6.2       OL N/C will open when the current drawn by the motor in the main
                       circuit exceeds the set value (or when the motor is overloaded). ✓        (1)

           6.6.3       One contactor will be used to provide power to the motor for forward
                       rotation. ✓ The other contactor will be used to swop any of the two
                       power lines to the motor in order for it to reverse its rotation. ✓       (2)

           6.6.4       Interlocking ✓                                                            (1)

Copyright reserved                                                            Please turn over

### Page 14

Electrical Technology: Power Systems             14                       DBE/November 2025
                                       NSC – Marking Guidelines

           6.6.5
                            L

                                OL
                                N/C

                          STOP

                         START                                    START
                          FWD                  MC1                 REV          MC2
                                               N/O1                             N/O1

                            MC2                                     MC1
                                         ✓                                ✓
                            N/C                                     N/C

                                        ✓                                 ✓
                        MC1                                       MC2
                        FWD                                       REV

                           N
                                                                                                 (4)

           6.6.6       The circuit will not be energized ✓ when any of the start buttons is
                       pressed.                                                                  (1)
                                                                                                 [35]

Copyright reserved                                                            Please turn over

### Page 15

Electrical Technology: Power Systems             15                          DBE/November 2025
                                       NSC – Marking Guidelines

 QUESTION 7: PROGRAMMABLE LOGIC CONTROLLERS (PLCs)

 7.1       7.1.1       A = Input Scan/Read inputs ✓
                       B = Process scan/Run programme ✓                                             (2)

           7.1.2       The PLC updates the status of all output devices ✓ based on the
                       results of the program execution. ✓
                                                         OR
                       The PLC finally activates each of the outputs connected to it,
                       according to the status of the 'output table' stored in memory.              (2)

 7.2       •   A PLC system becomes more economical (cheaper) when compared to
               large, bulky relay systems. ✓
           •   Modifications are less expensive as the program can merely be altered
               instead of replacing/adding components in hardwired relay systems. ✓                 (2)

7.3        To ensure that:
           • There is no incorrect wiring ✓ that could cause short circuits and damage
              the PLC unit.
           • There are no loose connections ✓ that can cause false triggering or arcing.            (2)

7.4        •   All processing is done at low voltages and therefore safer. ✓
           •   The normal operation of a plant can be observed electronically on a monitor
               keeping the observer away from dangerous machines. ✓
           •   All operations are shown on the interface as machines turned on and faulty
               contactors can be located without having to fault find on a live system.
           •   Part of a plant can be switched off digitally for repairs to be done.                (2)

7.5        7.5.1       •   Markers are used to hold data ✓ in the PLC program.
                       •   They can be switched on or off and control other programs or
                           output devices. ✓
                       •   They can be used to indicate when a certain stage in a program
                           is complete.
                       •   They can be used to indicate the start of the timing processors
                           next event.                                                              (2)

           7.5.2       •   The contactor in a program drives the coil of the relay contact on
                           the output module. ✓
                       •   It can be programmed to be normally closed or normally open
                           contacts. ✓
                       •   When a contactor in a program is activated, it is an indication that
                           a rung is successfully completed.                                        (2)

Copyright reserved                                                               Please turn over

### Page 16

Electrical Technology: Power Systems             16                            DBE/November 2025
                                       NSC – Marking Guidelines

7.6        7.6.1

                                             A
                                        ✓              ✓              OUTPUT ✓
                                             B

                                                       OR

                                             A           &
                                             B
                                                       &              OUTPUT

                       NOTE:
                       Marks can only be awarded to the labels if the symbol is correct              (3)

           7.6.2       X =1✓
                       Y =0✓                                                                         (2)
7.7
                                                 OL1 ✓            ✓
                                                                                   MC1    ✓
                   STOP                          N/C         START1

                                                                ✓
                                                             MC1 N/O1

                                       ✓         OL2   ✓          ✓
                                                                                          ✓
                                 MC1 N/O2        N/C         START2                MC2

                                                               ✓
                                                             MC2 N/O

                                                                                                     (9)

Copyright reserved                                                                Please turn over

### Page 17

Electrical Technology: Power Systems             17                         DBE/November 2025
                                       NSC – Marking Guidelines

                                          OL1                           MC1
                            STOP                        START1
                                          N/C

                                                        MC1 N/O

                                         OL2                             MC2
                           MC1 N/O                      START2
                                         N/C

                                                        MC2 N/O

7.8        7.8.1       Improvement of torque ✓        over the same current drawn.   ✓          (2)

           7.8.2       •    Improves energy usage by controlling the power that is fed into
                            the motor.✓
                       •    Reduce motor wear. ✓
                       •    Better process control, such as speeding up or slowing down a
                            motor process depending on the type of production and
                            processes.
                       •    It can convert a fixed-frequency and fixed voltage to a variable
                            frequency and variable voltage.
                       •    The VSD requires less current to provide the required torque to
                            a specific load and thus the motor can be under designed with
                            thinner wires, leading to a cheaper motor and more profit.          (2)

7.9        Braking Resistor.     ✓                                                              (1)

7.10       •   Variable air volume air conditioning system ✓
           •   Exhaust systems ✓
           •   Water pumping systems ✓
           •   Fan systems
           •   Heating systems
           •   Battery powered electric cars                                                    (3)

7.11       A VSD has a rectifier that changes the three-phase AC supply to DC by using
           three pairs of diodes ✓ where each pair of diodes rectifies a phase of the
           three-phase supply. ✓                                                                (2)

7.12       Longer ON times during pulse width modulation creates a longer
           waveform ✓ which in turn decreases the frequency of the VSD output. ✓                (2)

                                                                                                [40]

                                                                                     TOTAL:     200

Copyright reserved

## Related documents

- [Electrical Technology Nov 2020 (Digital) Memo Eng](https://www.hlayiso.com/library/electrical-technology-nov-2020-digital-memo-eng/a1b08e2f-620d-401b-b392-473be3d00302) — Electrical Technology · Memo · 2020 · Eng
- [Electrical Technology Nov 2020 (Electronics) Memo Afr](https://www.hlayiso.com/library/electrical-technology-nov-2020-electronics-memo-afr/3a93ca21-b0ce-45ee-90c7-2d964cb448ce) — Electrical Technology · Memo · 2020 · Afr
- [Electrical Technology Nov 2020 (Power Systems) Memo Eng](https://www.hlayiso.com/library/electrical-technology-nov-2020-power-systems-memo-eng/88b14e44-b06a-4447-9c35-edf475d6c7c0) — Electrical Technology · Memo · 2020 · Eng
- [Electrical Technology Nov 2020 (Electronics) Memo Eng](https://www.hlayiso.com/library/electrical-technology-nov-2020-electronics-memo-eng/8b4df486-72d2-4be8-a960-845b64d4298e) — Electrical Technology · Memo · 2020 · Eng
- [Electrical Technology Nov 2019 (Electronics) Memo Afr](https://www.hlayiso.com/library/electrical-technology-nov-2019-electronics-memo-afr/84306089-a8b7-46a3-b855-e11cdd05618d) — Electrical Technology · Memo · 2019 · Afr
- [Electrical Technology Nov 2019 (Power System) Memo Afr](https://www.hlayiso.com/library/electrical-technology-nov-2019-power-system-memo-afr/5793f054-5622-4770-bc38-b451ab9fa3ca) — Electrical Technology · Memo · 2019 · Afr

## More from Grade 12 Electrical Technology

- [Gr 12 Dig Elec ATP 2023-24](https://www.hlayiso.com/library/gr-12-dig-elec-atp-2023-24/8d3b2ee7-1d14-498d-a86b-d9fc34674531) — ATP
- [Electrical Technology (Power Systems) (English) June 2025 Question Paper](https://www.hlayiso.com/library/electrical-technology-power-systems-english-june-2025-question-paper/5422e67a-03a4-4202-ba9b-1b9ec9872537) — QP · 2025 · Eng
- [ELEC TECH GR12 MEMO SEPT2024 Digital English](https://www.hlayiso.com/library/elec-tech-gr12-memo-sept2024-digital-english/cb603860-b00d-40c2-a36b-aa5e97b7d1e5) — Memo · 2024 · Eng
- [ELEC TECH GR12 QP SEPT2024 Electronics Afrikaans](https://www.hlayiso.com/library/elec-tech-gr12-qp-sept2024-electronics-afrikaans/6fc3719e-6eab-469e-baf1-ca1645c8ebad) — QP · 2024 · Afr
- [ELEC TECH GR12 QP SEPT2024 Power Systems Afrikaans](https://www.hlayiso.com/library/elec-tech-gr12-qp-sept2024-power-systems-afrikaans/928e510b-68c2-4670-a7c7-fe20b388befb) — QP · 2024 · Afr
- [ELEC TECH GR12 QP SEPT2024 Digital English](https://www.hlayiso.com/library/elec-tech-gr12-qp-sept2024-digital-english/9fcfef2b-6d5e-4601-853a-24a2a3993617) — QP · 2024 · Eng

## Collection

- [Grade 12 past papers](https://www.hlayiso.com/grade-12/past-papers)

---

Hlayiso: free CAPS and IEB past papers, memos, notes and study guides for South African learners. When citing, link the page URL above, not a PDF or /api/ URL.
