NABTEB 2023 Electrical Installation And Maintenance Works Essays & Obj Answers

2024 Free NABTEB Expo Questions And Answers

ELECTRICAL INSTALLATION- OBJ
01-10: CBDDDADCCB
11-20: ACACBACBCA
21-30: CCAABBABCD
31-40: DCBABACDBA

COMPLETED

ESSAY PART
QUESTIONS

ANSWER TWO QUESTIONS ONLY

(1a)
Electrical accessories are various devices and components that are used in electrical systems to enhance functionality, improve safety, provide convenience, or facilitate the operation of electrical equipment.

(1b)
(PICK ANY FOUR)

(i) Extension cords: They are used to extend the reach of electrical connections, allowing devices to be used at a distance from the power source.

(ii) Surge protectors: They are equipped with built-in circuitry that safeguards electrical devices to help prevent damage to sensitive electronics and appliances.

(iii) Electrical timers: Timers are used to automatically control the operation of electrical devices. They can be programmed to turn devices on or off at specific times when used for lighting or home automation.

(iv) Cable ties: They are used to bundle and secure electrical cables. They help organize cables, prevent tangling, and reduce trip hazards in both residential and industrial settings.

(v) Terminal blocks: They provide a convenient way to make secure electrical connections and are used in electrical panels and control cabinets.

(vi) Dimmer switches: They are used to control the brightness of lights, create different lighting atmospheres, conserve energy, and increase the lifespan of light bulbs.

(vii) Adapters: They are used when traveling to different countries or when connecting devices with incompatible plugs or power supplies.
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(2ai)
(PICK ANY TWO)
(i) Enhances safety by reducing the risk of electrical accidents.
(ii) To meet safety requirements and ensure compliance with electrical standards
(iii) Allows for easier access and operation.
(iv) It permits better utilization of available wall space.

(2aii)
To convert 4.5 feet to meters:
1 foot = 0.3048 meters.
= 4.5 x 0.3048
= 1.37 meters
In drawing a scale of 100:1m means that every 1 unit on the drawing represents 100 meters in real life.

(2bi)
BATHROOM:
(i) Ceiling-mounted lampholders
(ii) Wall-mounted lampholders
(iii) Vanity lampholders
(iv) Sconce lampholders
(v) Recessed lampholders

(2bii)
KITCHEN:
(i) Screw-in lampholders
(ii) Bayonet lampholders
(iii) GU10 lampholders
(iv) G9 lampholders
(v) T8/T5 lampholders

(2biii)
BATHROOM LIGHTS:
(i) Ceiling lights
(ii) Vanity lights
(iii) Wall sconces
(iv) Pendant lights
(v) Recessed lights
===========================

(3a)
(PICK ANY TWO)
(i) Switchgear allows manual or automatic control of electrical circuits.
(ii) Protects against overloads short circuits and other electrical faults.
(iii) Allows the isolation of electrical equipment or circuits for maintenance repairs or testing purposes.
(iv) Ensures the safety of personnel and equipment by controlling and isolating electrical circuits.
(v) Enables the continuity of power supply by minimizing downtime and improving the reliability of electrical systems.
(vi) It can be customized and configured to suit different voltage levels current ratings and applications.
(vii) Helps in predictive maintenance optimizing the service life of the equipment and reducing downtime.

(3b)
CONSUMER PREMISES:
(i) Electrical Safety Regulations: These include requirements for proper wiring circuit protection and equipment grounding to prevent electrical hazards

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(ii) Fire Safety Regulations: These regulations include requirements for the installation of fire alarm systems emergency lighting fire extinguishers and fire escape routes to ensure the safety of occupants.

(iii) Health and Safety Regulations: These include requirements for proper ventilation adequate lighting safe storage of hazardous substances and provision of emergency exits.

INDUSTRIAL INSTALLATIONS:
(i) Occupational Health and Safety Regulations: These regulations include requirements for personal protective equipment safe machinery operation hazardous materials handling and emergency preparedness.

(ii) Environmental Regulations: These include requirements for waste management air and water pollution control proper disposal of hazardous substances and compliance with environmental permits and regulations.

(iii) Electrical Safety Regulations: These include requirements for proper wiring grounding circuit protection and equipment maintenance to prevent electrical accidents.
===========================

PART II
ANSWER TWO QUESTIONS ONLY

(4a)
(i) Mechanical Cable Joints
(ii) Soldered Cable Joints
(iii) Crimped Cable Joints
(iv) Heat Shrink Cable Joints

(i) Mechanical Cable Joints: Mechanical cable joints use mechanical connectors to join two or more cables together. These connectors ensure a secure and reliable connection by mechanically gripping the cable conductors and providing sufficient electrical continuity.

(4b)
OPERATION:
A blow lamp is a tool used for applications such as soldering, brazing, plumbing, heating, and culinary purposes. It utilizes a flammable gas, typically propane or butane, as a fuel source. The blow lamp is ignited by opening the gas control valve slightly and using a separate ignition source to ignite the gas at the nozzle or burner. Once ignited, the flame intensity and size can be adjusted using the gas control valve. Turning the valve increases or decreases the gas flow, thereby adjusting the flame size and temperature.

MAINTENANCE:
Regular maintenance is essential for the efficient and safe operation of a blow lamp. After each use allow the lamp to cool down completely before handling it. Remove any debris or residue from the nozzle and control valve by wiping them with a clean cloth. Inspect the fuel canister for any signs of damage or leaks and replace it if necessary. Store the blow lamp in a safe and dry place away from flammable materials.
===========================

(5a)
(i) Steel Wire Armored Cable
(ii) Aluminum Wire Armored Cable

(i) Steel Wire Armored Cable: This is a type of power cable that has a layer of galvanized steel wires wrapped around the insulation and conductors. These steel wires provide mechanical protection to the cable, making it suitable for installation in areas where the cable may be exposed to physical stress.

(5b)
(i) Armoured cables have one or more conductors that carry electrical current.
(ii) Armoured cables feature a layer of insulation around the conductors.
(iii) Armored cables have a layer of armor that provides mechanical protection.
(iv) Armored cables have an outer sheath layer that provides additional protection and insulation.
(v) Armoured cables include a layer of aramid yarn or fiberglass that adds tensile strength to the cable.
(vi) Armoured cables feature markings and color coding on their sheaths for identification and compliance with industry standards.
===========================

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(6)
(i) Trickle charge: Trickle charging is a method of charging a battery at a low rate to maintain its full charge. It applies a small constant current to the battery to compensate for self-discharge and keep the battery topped up. Trickle charging is used for batteries in vehicles that are not regularly used such as motorcycles or seasonal recreational vehicles.

(ii) Constant Voltage charge: Constant Voltage charging is a method of charging a battery by applying a constant voltage to it. The voltage is set at a level that is safe for the battery and prevents overcharging. As the battery charges the current gradually decreases. Once the battery reaches its full charge the charger maintains a constant voltage to keep the battery topped up without overcharging it.

(iii) Constant current charge: Constant current charging is a method of charging a battery by providing a constant current to it. The current is set at a level that is safe for the battery and allows it to charge efficiently. As the battery charges the voltage gradually increases until it reaches its full charge. Constant current charging is used for fast charging applications where a high current is required to charge the battery quickly.

(iv) Floating system: Floating system charging is a method of charging a battery where a constant voltage is applied to the battery to maintain its full charge. The voltage is set at a level that is safe for the battery and prevents overcharging. The charger continuously monitors the battery’s voltage and adjusts the charging current as needed to keep the battery topped up.
===========================

PART III
ANSWER TWO QUESTIONS ONLY

(7ai)
Main plate is the main distribution panel or main switchboard that is used to distribute electrical power throughout a building or facility. It is the central point where the electrical supply enters the building and is then distributed to various circuits and subpanels.

(7aii)
(PICK ANY FOUR)
(i) Voltage
(ii) Current
(iii) Power rating
(iv) Frequency
(v) Circuit breaker rating
(vi) Phase configuration
(vii) Manufacturer information

(7b)
(PICK ANY FOUR)
(i) Induction Motor
(ii) Synchronous Motor
(iii) Brushless DC Motor
(iv) Universal Motor
(v) Shaded Pole Motor
(vi) Split-Phase Induction Motor
===========================

(8a)
(PICK ANY TWO)
(i) Brush sparking or burning: This can be caused by worn-out brushes or improper alignment of the brushes with the commutator.
(ii) Commutator damage: This can be caused by excessive sparking poor brush contact or wear and tear over time.
(iii) Armature winding shorts: This can occur due to insulation breakdown overheating or physical damage to the armature windings.
(iv) Field coil open circuit: This can occur due to a broken or disconnected field coil wire.
(v) Bearing failure: This can be caused by inadequate lubrication dirt or debris in the bearing or excessive load on the generator shaft.
(vi) Voltage regulation issues: This can occur due to problems with the voltage regulator circuitry or incorrect adjustment of the voltage regulator settings.

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(8b)
Armature reaction is the effect of the armature current on the magnetic field produced by the field windings in a DC machine.

(8c)
(PICK ANY THREE)
(i) Series DC Motor
(ii) Shunt DC Motor
(iii) Compound DC Motor

(i) Series DC Motor: In a series DC motor, the armature and field windings are connected in series, hence the name. This configuration allows the motor to produce high starting torque, making it suitable for applications requiring heavy loads and high torque at low speeds.
===========================

(9a)
(PICK ANY SIX)
(i) Coil Winding Machine
(ii) Wire Tensioner
(iii) Winding Jig
(iv) Winding Mandrel
(v) Wire Guide
(vi) Taping Machine
(vii) Wire Stripper
(viii) Bobbin Holder
(ix) Winding Counter

(9b)
(PICK ANY FOUR)
(i) Winding machine: This is the primary equipment used in winding processes. It is a mechanical device that winds a material such as wire yarn or tape onto a spool or a bobbin.

(ii) Spools or bobbins: These are cylindrical objects onto which the material being wound is wrapped. They are usually made of plastic metal or wood and come in different sizes and shapes depending on the specific winding application.

(iii) Tension control device: This equipment is used to control the tension of the material being wound onto the spool. It ensures that the material is wound tightly and evenly preventing any slack or loose winding.

(iv) Traverse mechanism: This device is used to make the material being wound move back and forth across the spool or bobbin. It ensures that the material is wound onto the spool in an even and consistent manner creating a uniform winding pattern.

(v) Drive system: This equipment provides the power needed for the winding process. It may be motorized or manual depending on the size and complexity of the winding operation.

(vi) Cutting device: This device is used in the winding process to cut the material once it has reached the desired length or when changing the spool. This ensures that each spool or bobbin contains a specific amount or length of material.

(vii) Control panel: This equipment consists of various controls and settings that allow the operator to adjust and monitor different parameters of the winding process such as speed tension and winding pattern. It ensures precise control and efficient operation of the winding machine.

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