ESE Prelims Electrical case studies

ESE Prelims Electrical · Put your knowledge to work in context.

The Engineering Services Examination (Preliminary) in Electrical Engineering is a screening stage used by the Union Public Service Commission to shortlist engineering graduates for central government technical posts. It suits candidates with a B.E./B.Tech or equivalent in Electrical Engineering who want a career in public-sector engineering rather than private industry. The ESE Prelims Electrical case studies are 5 cases and about 4,962 words.

Noisy 4–20 mA Flow Signal on a Long Shielded Run With a VFD Nearby

A 4–20 mA signal from a loop-powered electromagnetic flowmeter in a remote pump house runs 210 m on shielded twisted pair to a PLC analogue input card. The card is single-ended, uses a 250 Ω sense resistor, and is specified at 60 dB CMRR at dc, falling to 45 dB at 50 Hz.

964 words, about 5 min 2

Induction Motor Tripping on Overload After Rewind With a 6% Supply Voltage Unbalance

A 415 V, 50 Hz, 75 kW, 4-pole, 1480 r/min cage induction motor drives a centrifugal pump through a belt. Full-load current is 132 A and the class 10 thermal overload relay is set at 132 A.

1,018 words, about 5 min 3

Distance Relay Three-Pole Trip Caused by a Blown CVT Fuse

A 220 kV, 150 km single-circuit line is protected by a numerical distance relay with quadrilateral zones: Zone 1 at 80% of the line, Zone 2 at 120%, Zone 3 at 200%, all set on an 85° line angle; the positive-sequence line impedance is 0.42 Ω/km. A VT-fuse-failure supervision function exists in the relay but has never been enabled, and the trip output is three-pole.

936 words, about 5 min 4

Motor Insulation and Bearing Failures on a Long Unshielded Inverter Cable

A 400 V, 50 Hz, 37 kW, 4-pole motor is fed from a PWM voltage-source inverter on a 400 V supply, giving a nominal dc bus of 565 V and 620 V at +10% line. The motor cable is 130 m of unshielded four-core PVC cable in a tray, with the frame earthed only through the tray.

1,025 words, about 5 min 5

Pressure Loop Limit-Cycling After a Positioner Overhaul

A PI controller in a PLC regulates a 6 bar compressed-air header by throttling a 150 mm butterfly valve with a pneumatic positioner. A step test gives a process gain of 0.8 bar per percent of valve opening, a time constant of 12 s and a dead time of 4 s.

1,019 words, about 5 min