Electrical Technology Digital Electronics Memo 1 (English)

November 2025 — Grade 12 / Matric — Electrical Technology

Memo 2025 Grade 12 English

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🎯 200 marks 📄 7 pages 📝 75 items found 📚 2 topics

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2.4All calculations must show the formulae. Substitution of values must be done correctly. All answers MUST contain the correct unit to be considered. Alternative methods must be considered, provided that the correct

2.5Where 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

Q1— Section header —

Q2— Section header —

2.1Any 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,

2.2Do t touch the person with bare hands se a non

2.3The use misuse of power tools without adhering to safety protocols The etching of PC boards without following safety procedures

2.4critical 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

2.5It is an unsafe act, because it creates an unsafe condition (no guard on the machine\ that is conducted

Q3— Section header —

3.1.1Resonant frequency

3.1.2Quality factor/Q factor (1\

3.2(3\

3.2(3\ OR Alternatively calculate R = 56 and X = 31,83 , then Z = 64,01

3.2.3OR If R is calculated: (3\ NOTE may also be used.

3.2.4At resonance X =X C, therefore (3\ Electrical Technology: Power Systems DBE/November 2025

3.3NOTE: and V are the TWO primary labels thereafter any TWO correct labels. If V , V

3.5The circuit is more inductive. The inductive current I is greater than the capacitive current I (2\

3.6When the frequency increase decreases and X increases

Q4— Section header —

4.1Installations 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.

4.2A p ower 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\

4.3.1Delta (1\

4.3.2400 V (1\

4.3NOTE: The following labels will be accepted given the sequence is correct: , L & L

4.4.1(3\ 120 120 120 RY YB

4.4.2(3\

4.4.3(3\ OR

4.4.4(3\ OR

4.5(3\ Electrical Technology: Power Systems DBE/November 2025 NSC Marking Guidelines Copyright reserved Please turn over 4.

4.6.3Coil B is the potential coil connected in parallel with the load to measure voltage. It is movable with a needle on it and w hen connected it

4.7.1Higher energy losses Thicker cables are required Larger switchgear is required Higher electricity bills

4.7.2A 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.

4.7.3A 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\

Q5— Section header —

5.1When 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.

5.3.1Voltage rating Current rating Turns ratio Power rating Efficiency

5.3.2It is used as step down transformers in distribution systems where a four wire system (neutral\ is required.

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

5.4In delta 5.

5.5(3\

5.6A 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. [30]30

Q6— Section header —

6.1Resistance/continuity test of the windings. Insulation resistance test between windings. Insulation resistance test between windings and earth. (2\

6.2The 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\

6.3.1Locked rotor torque Starting/Start up torque Breakdown

6.3.2The slip is minimum at no load speed. (1\ 6. 6. .1

6.5.1(3\

6.5.2(3\

6.5.3OR Electrical Technology: Power Systems 13 DBE/November 2025 NSC Marking Guidelines Copyright reserved Please turn over

6.5.4(3\ OR

6.6.1MC N/O Retain / hold in contact (1\

6.6.2OL 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\

6.6.3One 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

6.6.4Interlocking Electrical Technology: Power Systems 14 DBE/November 2025 NSC Marking Guidelines

6.6.5(4\

6.6.6The circuit will not be energized when any of the start buttons is pressed. (1\ [35] OL N/C35

Q7— Section header —

7.1.1A = Input Scan/Read inputs B = Process scan/Run programme (2\

7.1The 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

7.2A 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

7.3To 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\

7.4All 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

7.57.

5.1Markers 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.

7.67.

6.1NOTE: Marks can only be awarded to the labels if the symbol is correct 7.

6.2X = 1 = 0

7.7(9\ OUTPUT OUTPUT

7.8.1Improvement of torque over the same current drawn. (2\

7.8.2Improves 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

7.9Braking Resistor. (1\

7.10Variable air volume air conditioning system Exhaust systems Water pumping systems Fan systems Heating systems Battery powered electric cars

7.11A 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\

7.12Longer ON times during pulse width modulation creates a longer waveform which in turn decreases the frequency of the VSD output. (2\ [40] TOTAL: 200 STOP START40

Topics Identified

CircuitsMachines

Mark Allocation

Total200 marks

Sections15 + 10 + 35 + 35 + 30 + 35 + 40 = 200 marks

Paper information

SubjectElectrical Technology

Year2025

SessionNovember

TypeMemo

PaperPaper 1

LanguageEnglish

Pages17

Downloads8

Examination context

Decade2020s

Years ago1y

SeasonSpring (SH)

Start dayWednesday

Exam periodNovember 2025

Days since exam355

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