Maharashtra SSC Electrical Appliances (MSBSHSE) flashcards
Maharashtra SSC Electrical Appliances (MSBSHSE) · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Ohm's law
- Current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance, giving V = I × R at constant temperature.
- Electrical power formula
- Power in watts equals voltage multiplied by current, P = V × I, and can also be written as I²R or V²/R for resistive loads.
- Series circuit rule
- In a series circuit the same current flows through every component, the total resistance is the sum of the resistances, and the supply voltage divides across them.
- Parallel circuit rule
- In a parallel circuit every branch has the same voltage, the branch currents add, and the total resistance is less than the smallest individual resistance.
- Nichrome heating element
- A nickel-chromium alloy with high resistivity, high melting point and resistance to oxidation at red heat, making it the standard material for heater elements.
- Mica as insulator
- A mineral insulator that withstands high temperature and has good dielectric strength, so it is used as a sheet between the element and the soleplate of irons.
- Lockout and tagout
- A safety procedure in which the supply is isolated, the fuse removed or breaker locked, a warning tag fixed, and the circuit proved dead before work begins.
- Electrical fire extinguisher
- Carbon dioxide or dry powder extinguishers are used on live electrical fires because they do not conduct; water and foam must never be used.
- Conduit wiring
- A wiring system in which insulated conductors are drawn through PVC or steel pipes fixed on or inside a wall, giving mechanical protection and, with steel, earth continuity.
- Two-way switch
- A three-terminal switch with one common and two way contacts, wired in pairs so a lamp can be controlled from two different positions.
- Earth pin of a socket
- The earth pin is longer and thicker than the live and neutral pins so the earth connection makes first and breaks last when a plug is inserted or removed.
- Automatic iron thermostat
- A bimetallic strip inside the iron bends as it heats and opens the element contacts at the set temperature, closing them again on cooling to hold the heat steady.
- Universal motor
- A series-wound motor with brushes and a commutator that runs on either AC or DC, giving high speed and high starting torque for mixers and drills.
- Capacitor-start motor
- A single-phase induction motor whose auxiliary winding is fed through a large capacitor to create starting torque; a centrifugal switch disconnects it near running speed.
- Ceiling fan capacitor fault
- If the run capacitor loses capacitance the fan hums without turning or needs a push to start, because the auxiliary winding no longer produces enough phase shift.
- MCB function
- A resettable miniature circuit breaker that trips on overload by thermal action and on short circuit by magnetic action, protecting wiring in the phase conductor.
- RCCB 30 mA
- A current-operated earth leakage device that trips when the phase and neutral currents differ by about 30 mA, the level chosen to protect people from fatal shock.
- Purpose of earthing
- Earthing connects metal appliance bodies to the ground so a fault current flows and trips the protective device, keeping the body at safe potential.
- Earth continuity test
- A dead test using a multimeter or ohmmeter between the appliance metal body and the earth pin, expected to read close to zero ohms.
- Megger insulation test
- A test applying 500 V DC between live parts and the metal body; a sound appliance shows insulation resistance above one megohm.
- Open circuit fault
- A break in the conductor path, such as a burnt element or broken wire, shown by infinite resistance and a completely dead appliance.
- BEE star rating
- An Indian label from one to five stars showing the energy efficiency of an appliance, with five stars the most efficient and annual consumption stated in kWh.
- Energy efficiency formula
- Efficiency equals useful output energy divided by total input energy, multiplied by one hundred and expressed as a percentage; losses appear mainly as heat.
- Resistance of a conductor
- Resistance equals resistivity times length divided by cross-sectional area, so a longer or thinner wire has more resistance than a short thick one.
- Fuse wire material
- A tin-lead alloy with a low melting point, chosen so the fuse melts and breaks the circuit before the wiring or appliance winding overheats.
- Insulated hand tools
- Tools with moulded insulation on the handles, rated for a stated voltage such as 1000 V, used to reduce shock risk during electrical work.
- Wire gauge selection
- Conductor size is chosen from the load current and permitted voltage drop: about 1.0 mm² for lighting, 1.5 to 2.5 mm² for socket circuits.
- Loop-in wiring system
- A wiring method in which the supply and switched wires are looped through the ceiling rose, so the switch drop cable runs from rose to switch.
- Geyser thermal cut-out
- A one-shot safety device that opens the element circuit permanently if the thermostat fails and water temperature exceeds a safe limit.
- Thermal relay protection
- A bimetal or heater-operated relay in a motor circuit that opens the contactor when sustained overload current raises winding temperature above a safe value.
- Short circuit fault
- An unintended low-resistance path between phase and neutral or phase and earth, causing very large current that blows the fuse or trips the breaker at once.
- Standby power loss
- Small continuous consumption by appliances left in standby mode, avoided by switching off at the socket or using a master switch strip.