Maharashtra SSC Electrical & Hardware Installation Tech Pre-Voc/NSQF flashcards
Maharashtra SSC Electrical & Hardware Installation Tech Pre-Voc/NSQF · 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
- The current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance: V equals I times R.
- Insulation resistance test
- A test using a megger at 500 V DC on a dead low-voltage circuit, expecting at least 1 megohm, to prove the insulation is sound.
- RCD sensitivity
- The earth-leakage current at which a residual current device trips; 30 mA is used for personal protection and 100 to 300 mA for fire protection.
- Lockout/tagout
- A procedure where the isolator is locked, a warning tag with the holder's name is attached, and the circuit is proved dead before work starts.
- Series circuit rule
- Current is the same through all elements, voltages add, and total resistance is the sum of the individual resistances.
- Parallel circuit rule
- Voltage is the same across all branches, currents add, and total resistance is found from the reciprocal sum of the branch resistances.
- Power factor
- The ratio of real power in watts to apparent power in volt-amperes, equal to the cosine of the phase angle between voltage and current.
- Three-phase power formula
- Real power equals square root of three times line voltage times line current times power factor for a balanced three-phase load.
- Copper versus aluminium
- Copper has lower resistivity, about 0.0172 ohm-mm squared per metre, so aluminium needs a larger cross-section for the same current.
- PVC insulation limit
- Polyvinyl chloride cable insulation has a maximum continuous conductor temperature of about 70 degrees Celsius.
- Two-way switch
- A three-terminal switch with a common and two strappers, used in pairs to control one lamp from two positions such as a staircase.
- MCB versus RCD
- An MCB protects against overload and short circuit, while an RCD protects against earth leakage; an RCBO combines both functions.
- Clamp meter rule
- A clamp meter surrounds one conductor only; clamping live and neutral together reads near zero because their magnetic fields cancel.
- Megger safety rule
- An insulation tester must only be used on a dead circuit, and electronics must be disconnected because the test voltage can destroy components.
- Screw size notation
- A screw marked 8 by 50 means gauge 8 diameter and 50 millimetres length; wood screws taper while machine screws have parallel shanks.
- Wall plug selection
- The plug and drill bit are chosen by screw gauge and base material; plastic anchors suit brick, metal anchors suit concrete and heavy loads.
- Chemical anchor curing
- A resin anchor must be left for its full curing time at the ambient temperature before any load is applied to the fixing.
- Ceiling fan hook rule
- The fan hook must be embedded in the structural slab or a rated anchor, and the fan must be connected to the protective earth.
- Fan capacitor fault
- A fan that hums without starting commonly has a failed run capacitor or a seized bearing; the replacement must match microfarads and voltage.
- Heating element test
- A good element reads a low finite resistance on a multimeter, an open element reads infinity, and a shorted element reads near zero.
- Appliance earth test
- Measure resistance between the plug earth pin and the metal casing; a passing appliance reads near zero ohm, proving the earth path.
- Lamp circuit symbol
- A circle with a cross inside represents a lamp or signal light on an electrical schematic diagram.
- Schematic versus wiring diagram
- A schematic shows electrical connections without physical position, while a wiring diagram shows actual terminal-to-terminal connections for installation.
- Contactor coil terminals
- In a contactor, A1 and A2 are the coil terminals, and auxiliary contacts are numbered 13-14 for normally open and 21-22 for normally closed.
- Holding contact
- A normally open auxiliary contact wired in parallel with the start button so the contactor coil stays energised after the button is released.
- Star-delta interlock
- In a star-delta starter the star contactor must open before the delta contactor closes, otherwise a short circuit occurs across the supply.
- CPR compression ratio
- For an adult, give 30 chest compressions at 100 to 120 per minute to a depth of 5 to 6 centimetres, then 2 rescue breaths.
- Electrical fire extinguisher
- Electrical fires are fought with carbon dioxide or dry powder extinguishers only; water and foam conduct and must never be used.
- IP rating meaning
- The first digit shows protection against solid objects and the second against water, so IP44 is splash-proof and IP65 is dust-tight and jet-proof.
- Near-miss reporting
- An unplanned event that did not cause injury but could have must be recorded and investigated as a warning of a future accident.
- Quotation versus bill
- A quotation is an offer of price with a validity period before work, while a bill is a demand for payment after the work is completed.
- Selling price formula
- When margin is expressed on selling price, divide total cost by one minus the margin percentage to obtain the selling price.