UEECD0043 — Solve problems in direct current circuits

Elements & performance criteria

Performance evidence

• altering an existing circuit to comply with specified operating parameters
• applying Ohm’s Law to solve problems in direct current (d.c.) single path circuits
• applying relevant work health and safety (WHS)/occupational health and safety (OHS) requirements, including identifying risks and applying risk control measures
• calculating resistance of a conductor from factors such as conductor length, cross-sectional area, resistivity and changes in temperature and material
• connecting analogue/digital ammeter into a circuit ensuring the polarities are correct to take current readings
• connecting a series d.c. circuit containing capacitor and resistor to determine the time constant of the circuit
• calculating quantities from given information to determine capacitance, energy and voltage
• calculating one time constant as well as the time taken to fully charge and discharge a given capacitor
• calculating equivalent capacitance of capacitors connected in series and parallel circuits
• dealing with unplanned events in accordance with workplace procedures in a manner that minimises risk to personnel and equipment
• demonstrating graphical relationships of voltage, current and resistance
• calibrating and using measuring device in accordance with manufacturer specifications
• determining the operating parameters of an existing circuit
• developing circuits to comply with a specified function and operating parameters
• identifying and applying electrical industry standard symbols to represent electrical components in circuit diagram
• identifying fixed and variable resistors, including: determining resistance of a colour coded resistor from colour code tables and confirming the value by measurement, measuring resistance of variable resistors under varying conditions of light, voltage and/or temperature, selecting a resistor for an application
• solving problems in series and series-parallel circuits, including: developing, setting up and connecting a single source d.c. series-parallel circuit, measuring voltage and current, calculating resistance, voltage, current and power from measured and/or given values of any two of these quantities in a single source series-parallel circuit
• using test equipment to confirm the effect of material length, cross-sectional area and temperature on the resistance of conductive materials
• selecting an appropriate meter in terms of units to be measured, range, loading effect and accuracy for a given application
• using measuring devices to Solve problems in direct current circuits
• using meters for problem solving, including measuring resistance using direct, volt-ammeter and/or bridge methods
• using methodical techniques to solve d.c. circuit problems from measured and calculated values.

Knowledge evidence

• electrical concepts, including: calculations involving quantity of electricity, velocity and speed, distribution of electricity from the source to the load via the transmission systems, principle of conservation of energy, production of electricity, including: renewable and non-renewable energy sources, static and current electricity, utilisation of electricity by the various loads
• electrical circuit, including: industry standard symbols used to represent components in an electrical circuit diagram, multiple and sub-multiple units, purpose of each component in the electrical circuit
• Ohm’s Law, including: d.c. single path circuit, determining voltage, current and resistance in a circuit, effects of an open circuit, a closed circuit and a short circuit on a d.c. single path, relationship between voltage and current from measured values in a circuit, graphical relationships of voltage, current and resistance, relationship between voltage, current and resistance, voltage and current levels in a d.c. single path circuit
• electrical power, including: effects of power rating of various resistors, methods for measuring of electrical power in a d.c. circuit, power dissipated in circuit from voltage, current and resistance values, power ratings of electrical devices, relationship between force, power, work and energy
• effects of electrical current, including: relevant industry standards relating to fundamental principles for protection against the damaging effects of current, mechanisms by which metals corrode, principles by which electric current can result in the production of: heat, magnetic fields, a chemical reaction, typical uses of electrical current, physiological effects of current
• electromotive force (EMF) sources and conversion of electrical energy, including: input, output, efficiency and losses of electrical systems and machines, principles of generating an EMF, including: when a mechanical force is applied to a crystal, when moving a conductor in a magnetic field, by the application of light falling on the surface of photovoltaic (PV) cells, from the heating of one junction of a thermocouple, principles of producing an electrical current from primary, secondary and fuel cells
• resistors, including: types and applications of fixed and variable resistors used in the electrotechnology industry, characteristics of variable resistors used in the electrotechnology industry, including: adjustable resistors: potentiometer and rheostat, light dependent resistor (LDR), voltage dependent resistor (VDR), temperature dependent resistor, power ratings of a resistor, power loss (heat) occurring in a conductor, resistor colour code tables
• series, parallel, and series-parallel circuits, including: applications where these circuits are used in the electrotechnology industry, characteristics of series, parallel, and series-parallel circuits, including: connection of loads, current path, voltage drops, power dissipation, effects of an open circuit, diagrams of single source d.c. series, parallel, and series-parallel circuits, identification of the components of series, parallel, and series-parallel circuits, including power supply, loads, connecting leads and switch, relationship between voltage drops and resistance in a simple voltage divider network, techniques for determining voltage, current, resistances or power dissipated from measured or given values (of any two of these quantities), relationship between branch currents and resistances in a two-branch parallel and series-parallel current divider network
• factors affecting the resistance of a conductor, including: conductor length, cross-sectional area, resistivity, changes in temperature and material, effect the change in cross-sectional area, length and type of material has on the resistance of a conductor, effects of resistance on the current-carrying capacity and voltage drop in cables, effects of temperature change on the resistance of various conducting materials
• effects of measuring devices in a circuit, including: advantages and disadvantages of each voltage indicator tester, calibration and use of the measuring device, methods for connecting an analogue/digital voltmeter into a circuit ensuring the polarities are correct and taking various voltage readings, correct techniques to read the scale of an analogue meters and how to reduce the ‘parallax’ error, hazards associated with the use of measuring devices, including polarity, hazards involved in using electrical instruments and the safety control measures that should be taken, instruments used in the field to measure voltage, current, resistance and insulation resistance and the typical circumstances in which they are used, methods for using insulation resistance measuring devices to relevant industry standards, loading effect of various voltmeters when measuring voltage across various loads, methods for measuring resistance using direct, volt-ammeter and bridge methods, non-contact voltage indicator types and use, operating characteristics of analogue and digital meters, connecting an analogue/digital voltmeter into a circuit ensuring the polarities are correct and taking various voltage readings, operation of various voltage indicator testers, purpose and characteristics of a voltmeter, purpose of an ammeter and the correct connection (series) of an ammeter into a circuit, reasons the internal resistance of an ammeter must be extremely low and the dangers and consequences of connecting an ammeter in parallel and/or wrong polarity
• methods for selecting an appropriate meter in terms of units to be measured, range, loading effect and accuracy for a given application
• types of voltage indicator testers, including light-emitting diode (LED), neon, solenoid, volt-stick and series tester and the purpose of each voltage indicator tester
• methods for using voltage indicator testers to detect the presence of various voltage levels
• capacitors and capacitance, including: construction of a standard capacitor, different types of dielectric material and each dielectric’s relative permittivity, types of capacitors commonly used in the electrotechnology industry, industry standard symbol of various types of capacitors, including standard, variable, trimmer and polarised, terms and units for capacitance, electric charge and energy, factors affecting capacitance, behaviour of a series d.c. circuit containing resistance and capacitance components. - charge and discharge curves, arrangement of a series d.c. circuit containing capacitance and resistor to determine the time constant of the circuit
• capacitors in series and parallel, including: application of capacitors in the electrotechnology industry, common faults in capacitors, arrangement of capacitors in series and/or parallel configurations to achieve various capacitance values, equivalent capacitance of capacitors connected in series and parallel, effects of capacitors connected in parallel by calculating their equivalent capacitance, effects on the total capacitance of capacitors connected in series by calculating their equivalent capacitance, hazards involved in working with capacitance effects and the safety control measures that should be taken, including safe handling and the correct methods of discharging various size capacitors, dangers of a charged capacitor and the consequences of discharging a capacitor through a person, testing of capacitors to determine serviceability.

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Questions about assessing UEECD0043