BHEL Supervisor Trainee flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Maximum bending moment, simply supported

For a simply supported beam of span L with a central point load W, the maximum bending moment is WL/4, occurring at mid-span where shear force changes sign.

Thermal stress in constrained bar

A bar fully restrained at both ends and heated by ΔT develops stress α·ΔT·E. Length and cross-section do not affect the stress value, only the resulting force.

Three-phase power formula

In a balanced three-phase circuit, total active power is P = √3·V_L·I_L·cos φ, where V_L and I_L are line voltage and line current and cos φ is the power factor.

Transformer EMF equation

The RMS induced EMF per winding is E = 4.44·f·N·Φ_max, where f is supply frequency, N the turns and Φ_max the peak core flux in webers.

Ideal op-amp assumptions

An ideal operational amplifier has infinite open-loop gain and infinite input impedance, so input current is zero and the differential input voltage between the two terminals is zero.

Eutectoid point in iron–carbon diagram

At 0.76% carbon and 723 °C, austenite transforms into pearlite, an alternating lamellar mixture of ferrite and cementite, on slow cooling.

First-order batch reactor time

For a first-order reaction, time t = −ln(1 − X)/k, where X is conversion and k the rate constant; reaching 90% conversion takes 2.303/k.

Successive percentage change

Two successive changes of a% and b% produce a net change of a + b + (ab/100) percent. A 20% increase followed by a 20% decrease gives a net 4% decrease.

Relation between CI and SI

For two years, compound interest exceeds simple interest by P(R/100)², where P is principal and R the annual rate percent compounded yearly.

Work done together

If A alone finishes a job in a days and B in b days, working together they finish it in ab/(a + b) days, because their one-day rates add.

Alligation rule

When two ingredients of prices c and d are mixed to a mean price m, the ratio of their quantities is (m − c) : (d − m), with the cheaper price taken first.

Repeated replacement in mixtures

If x litres are drawn from V litres of pure liquid and replaced by water, repeated n times, the original liquid remaining is V(1 − x/V)^n litres.

Opposite letters in coding

In the English alphabet, letters whose positions sum to 27 are opposites, such as A–Z, B–Y and C–X; this resolves reversal-based coding and decoding questions quickly.

Syllogism validity rule

A conclusion from syllogism premises is valid only if it holds in every possible Venn diagram consistent with those premises, not merely in one convenient diagram.

Clock hand angle formula

The angle between the hour and minute hands at H hours and M minutes is |30H − 5.5M| degrees; if this exceeds 180, subtract it from 360.

Circular seating facing centre

When people face the centre of a circle, a person's left-hand neighbour sits clockwise from them and the right-hand neighbour anticlockwise, which fixes relative positions.

Article 32 of the Constitution

Article 32 gives the right to move the Supreme Court for enforcement of Fundamental Rights; Dr B. R. Ambedkar called it the heart and soul of the Constitution.

Standard Meridian of India

India's Standard Meridian is 82°30′ E, passing near Mirzapur, giving Indian Standard Time as UTC + 5 hours 30 minutes for the whole country.

Repo rate

The repo rate is the interest rate at which the Reserve Bank of India lends short-term funds to commercial banks against government securities, used to control liquidity.

Bharat Ratna

Instituted in 1954, the Bharat Ratna is India's highest civilian award, given for exceptional service in any field without restriction of race, occupation or sex.

Neither–nor verb agreement

With correlative conjunctions either–or and neither–nor, the verb agrees in number and person with the subject nearer to it, as in 'Neither the boys nor the teacher was present'.

Present perfect with since and for

The present perfect tense (has/have plus past participle) is used with 'since' for a starting point and 'for' for a duration continuing to the present.

Uncountable nouns

Nouns such as furniture, information, advice, luggage and equipment take singular verbs and no plural -s; quantities are expressed with pieces of or items of.

Passive voice formation

To change active to passive, make the object the subject, use the correct tense of 'be' with the past participle, and add the agent after 'by'.

Hole basis system

In the hole basis system the hole's lower deviation is zero and the hole size is fixed, while the shaft tolerance varies to obtain clearance, transition or interference fits.

Micrometer least count

The least count of a micrometer equals screw pitch divided by the number of circular scale divisions; a 0.5 mm pitch with 50 divisions gives 0.01 mm.

First-angle projection layout

In first-angle projection the object lies between observer and plane, so the top view is drawn below the front view and the left-side view to its right.

Insulation resistance measurement

Insulation resistance of low-voltage equipment is measured with a 500 V megger, and acceptable readings are in the megohm range, not kilo-ohms.

Hydrodynamic lubrication

In a journal bearing, rotation drags oil into a converging wedge, generating pressure that separates the surfaces; an external pump is not required for film formation.

Permit to work system

A permit records the job, isolation points, validity and authorised signatories; it is accepted before work begins and closed only after the site is verified safe.

Lockout–tagout principle

Energy sources are isolated, locked and tagged by the person doing the work, and zero energy is verified by test before work starts; only the lock holder removes the lock.

Confined space oxygen range

Entry into a confined space requires oxygen between 19.5% and 23.5% by volume, tested before entry, with forced ventilation and a standby observer at the entrance.