UPMSP Vocational Domestic Electrical Appliances & Repair key terms

A safety connection that gives fault current a low-resistance path to the earth so that metal appliance bodies cannot stay live and shock a user, and so protective devices trip quickly.

A residual current device that compares live and neutral currents and trips when a small leakage (typically 30 mA) flows to earth, protecting people from electric shock.

A miniature circuit breaker that automatically opens a circuit on overload or short circuit and can be reset by hand, replacing fuses in domestic distribution boards.

The current value at which a fuse element melts and breaks the circuit; it must be chosen just above normal load current but below the current-carrying capacity of the wiring it protects.

The relationship stating that voltage equals current multiplied by resistance (V = IR); used to calculate expected current, voltage drop, or heater resistance in appliance circuits.

The rule that electrical power equals voltage times current (P = VI) for resistive loads; used to find heater wattage, appliance current draw, and suitable cable size.

The ratio of real power to apparent power in an AC circuit, caused by motors and inductive loads; a low value means higher current for the same useful output.

The resistance measured between live conductors and the metal body of an appliance; a low reading indicates moisture, damage, or breakdown that can cause leakage current and shock.

The standard thickness designation of a conductor, which determines its current-carrying capacity; domestic appliance circuits commonly use 1.0, 1.5, 2.5, or 4.0 sq mm copper.

The loss of voltage along a cable caused by its resistance under load; excessive drop makes motors strain and heaters underperform, so cable length and thickness must be checked.

An instrument that applies a high DC test voltage to measure insulation resistance in megohms, used to check appliance windings, cables, and heating elements for breakdown or moisture.

A combined measuring instrument for voltage, current, resistance, and continuity; the technician's basic tool for tracing supply faults and checking appliance components.

A meter with a hinged jaw that measures current by sensing the magnetic field around a single conductor, allowing load current checks without breaking the circuit.

A resistance check, usually with a buzzer, confirming that a path exists through a wire, switch, thermostat, or fuse; an open reading means the component or connection is broken.

Two ways of connecting loads: series gives one path with shared voltage, parallel gives separate paths with full voltage each; domestic appliances and most heater elements are paralleled.

A temperature-sensing switch that opens and closes contacts to hold an appliance at a set temperature; bimetallic types are common in irons, heaters, and geysers.

A one-shot or resettable safety device that opens the circuit when a preset temperature is exceeded, protecting an appliance when the main thermostat fails closed.

A resistive coil or sheathed wire that converts electric current into heat; its resistance and length set the wattage, and a break in it stops all heating.

A method where an alternating magnetic field from a coil induces eddy currents in a ferromagnetic pot, heating the vessel directly rather than the glass surface.

An insulated-gate bipolar transistor used as a fast power switch in induction cooktops and inverter appliances, chopping DC into high-frequency AC to drive the heating coil or motor.

A component that creates a phase shift to give a single-phase motor starting torque or improve running efficiency; a failed capacitor causes humming, no start, or weak operation.

The coils of copper wire inside a motor that produce the magnetic field; checks include continuity for open windings and insulation resistance for shorts to the frame.

A speed-operated switch inside some single-phase motors that disconnects the start winding once the rotor reaches speed; sticking contacts prevent starting or keep the start winding energized.

The fluid in a refrigeration circuit that absorbs heat by evaporating at low pressure and releases it by condensing at high pressure; common domestic types include R-134a and R-600a.

The pump at the heart of a refrigerator or air conditioner that raises refrigerant pressure and circulates it around the sealed circuit; it is driven by a motor inside a sealed casing.

A narrow fixed-bore tube that throttles refrigerant from the high-pressure side to the low-pressure evaporator, controlling flow in small domestic refrigeration systems.

A thermal or current-operated device fitted to a compressor or motor that opens the supply when it overheats or draws excess current, then resets automatically after cooling.

A component whose resistance changes with temperature or another physical quantity, feeding a control board; an open or drifted sensor causes wrong readings and faulty appliance behaviour.

The electronic module that converts incoming AC to DC and then to variable-frequency output, controlling motor or compressor speed; it contains power devices, sensors, and fault detection.

A switched-mode power supply that converts mains AC into the low DC voltages needed by a control board; a failed SMPS leaves the appliance completely dead with no display.

A logical process of gathering the complaint, testing from supply to load, and eliminating possible causes one by one until the defective component is identified before any replacement.

Running a motor-driven appliance without its load to check current draw, speed, noise, and heating; abnormal readings point to bearing, winding, or capacitor faults.

A written statement of the likely repair cost, parts, and time given to the customer before work begins, protecting both technician and customer from later disputes.

Documentation of the appliance's purchase date, warranty period, and past repairs, used to decide whether a repair is free, chargeable, or should be referred to the brand's service centre.

The process of listening without argument, confirming the fault, explaining options clearly, agreeing a price, and following up after repair so the customer trusts the workshop.

Safety items such as insulated gloves, goggles, footwear, and aprons worn while testing or repairing appliances to reduce shock, burn, cut, and refrigerant exposure risks.

A procedure of isolating the supply, removing or locking the plug and fuse, and tagging the point so an appliance cannot be re-energized while someone is working on it.