BHEL Supervisor Trainee key terms

The ratio of a material's failure strength to the working stress it actually carries. A higher value means a larger margin against unexpected loads, defects, or overload in service.

The stress at which a material begins to deform permanently instead of returning to its original shape. Designers compare it with applied stress to decide safe component dimensions.

The maximum stress a material withstands while being pulled before it necks and breaks. It marks the peak of the stress-strain curve and guides selection of ductile structural materials.

A graph plotting applied stress against resulting strain for a test specimen. Its elastic region, yield point, and fracture point reveal stiffness, ductility, and strength of the material.

The stress a component is designed to experience under normal service loads. It is kept below the material's strength by the factor of safety chosen for that application.

The maximum stress a code or design standard permits in a member under specified loads. It is derived from material strength divided by a prescribed safety factor.

The ratio of real power in watts to apparent power in volt-amperes in an AC circuit. A low value means more current for the same useful power and higher losses.

The product of RMS voltage and RMS current in an AC circuit, measured in volt-amperes. It combines real and reactive power and sizes cables, transformers, and switchgear.

Power that oscillates between source and reactive elements such as inductors and capacitors without doing useful work, measured in volt-amperes reactive. It sustains magnetic fields in motors and transformers.

Deliberately connecting exposed metalwork or a circuit neutral to the ground so fault current flows safely away. It limits touch voltage and lets protective devices trip quickly.

A protective switch that trips when it detects a small imbalance between live and neutral currents, indicating leakage to earth. It guards people against electric shock.

A switch that automatically opens a circuit on overload or short circuit and can be reset after the fault clears. Its rating must coordinate with cable capacity and upstream devices.

A static device that transfers electrical energy between two windings at different voltage levels through mutual induction. It changes voltage and current while keeping frequency essentially unchanged.

A machine element that supports a rotating shaft while reducing friction between moving surfaces. Plain and rolling types differ in load capacity, speed limits, and lubrication needs.

Introducing oil, grease, or another film between moving surfaces to reduce friction and wear and to carry away heat. Correct selection depends on speed, load, and temperature.

Scheduled inspection, cleaning, and replacement work carried out before equipment fails. It reduces unplanned breakdowns and extends the service life of machines and systems.

A formal written authorisation required before hazardous maintenance or hot work begins. It records isolations, precautions, and sign-offs so that energy sources stay controlled.

A procedure in which energy isolating devices are locked and tagged so equipment cannot be re-energised during maintenance. Only the person who applied the lock removes it.

Clothing and gear such as helmets, gloves, goggles, and safety shoes worn to shield a worker from workplace hazards. It is the last line of defence after elimination and engineering controls.

The ranked order of hazard controls: eliminate, substitute, engineer, administrate, then use protective equipment. Earlier steps are more reliable because they remove the hazard rather than rely on behaviour.

The comparison of two quantities by division and the statement that two such comparisons are equal. Unitary and cross-multiplication methods solve most aptitude problems on sharing and mixing.

A fraction expressed with denominator one hundred, used to compare quantities on a common scale. Profit, loss, discount, and interest problems are usually built on percentage change.

The sum of a set of values divided by the number of values. Weighted and combined averages appear frequently in data interpretation and mixture problems.

Interest calculated only on the original principal for the whole period, without compounding. The formula is principal times rate times time divided by one hundred.

Problems relating the rate at which individuals or machines complete a task to the total time taken. Rates add when workers act together, so work done per day is the key quantity.

A reasoning question presenting two or more premises and asking which conclusion follows necessarily. Venn diagrams help test whether a conclusion is always true.

Reasoning puzzles that describe family links in words and ask how two people are related. Drawing a small family tree with standard symbols prevents confusion.

Finding the rule behind a sequence of numbers, letters, or figures and identifying the missing term. Differences, ratios, squares, and alternating patterns are common rules.

Two ways of framing a sentence according to whether the subject performs or receives the action. Passive forms are built with the verb to be plus the past participle.

Reporting someone's words either exactly in quotation marks or as a paraphrased clause. Indirect speech shifts tense, pronouns, and time words to match the reporting verb.

The rule that a verb must match its subject in number and person. Errors usually arise with collective nouns, indefinite pronouns, and phrases inserted between subject and verb.

Replacing a phrase with a single precise word, as tested in vocabulary sections. Candidates should learn common prefixes, roots, and standard substitutions rather than guess.

Fixed expressions whose meaning cannot be worked out from the individual words. Questions ask for the correct meaning or a suitable replacement in a sentence.

The supreme law of the country, adopted in 1949 and enforced from 26 January 1950. It sets out fundamental rights, directive principles, and the structure of government.

Guaranteed civil freedoms in Part III of the Constitution, enforceable in courts. They cover equality, speech, religion, and constitutional remedies against state action.

The three-tier system of local self-government in rural India created by the 73rd Constitutional Amendment. It gives elected bodies powers over local development and welfare.

Controlled heating and cooling of a metal to alter its microstructure and properties. Annealing softens, quenching hardens, and tempering restores toughness after hardening.

Joining metals by melting and fusing their edges, usually with a filler material. Electrode selection, current setting, and joint preparation govern weld strength and defects.