TSSPDCL Sub-Engineer case studies
TSSPDCL Sub-Engineer · Put your knowledge to work in context.
The TSSPDCL Sub-Engineer recruitment test is the screening examination used by the Telangana State Southern Power Distribution Company Limited to shortlist candidates for the Sub-Engineer (Electrical) post in its distribution circles. It is aimed at diploma and degree holders in electrical engineering who want a state utility career in operation and maintenance of 11 kV and 33 kV distribution networks, substations, metering and consumer service. The TSSPDCL Sub-Engineer case studies are 5 cases and about 3,444 words.
1Neutral current in an unbalanced four-wire LT feeder
A 415 V, three-phase, four-wire LT feeder supplied from a 630 kVA distribution transformer serves a commercial block with mixed single-phase loads. The cable is 4-core 95 mm² aluminium XLPE, 300 m long, installed in a duct; the neutral is the same size as the phase conductors.
647 words, about 3 min2Parallel transformers with unequal impedance and a tap mismatch
An 11 kV/433 V industrial substation has two Dyn11 transformers operating in parallel on the same LV bus: T1 is 1000 kVA with 5.0% impedance and T2 is 750 kVA with 6.0% impedance. The site load is 1600 kVA at 0.9 power factor.
698 words, about 3 min3Overcurrent relay grading on an 11 kV motor feeder
A 33/11 kV substation feeds an 11 kV industrial feeder through a 400/5 A CT and a microprocessor overcurrent relay set on the IEC standard inverse curve, plug setting 100% and TMS 0.10. The feeder supplies a 2.0 MW, 11 kV, four-pole induction motor with a rated current of about 123 A and direct-on-line starting current of 6 times full load, accelerating in 9 s.
726 words, about 4 min4VFD trips on DC bus overvoltage during fan deceleration
A 90 kW, 415 V, four-pole centrifugal fan is driven by a 110 kW variable-frequency drive. The fan runs at 1480 rpm and the total rotating inertia is 25 kg·m².
735 words, about 4 min5Lighting retrofit and payback in a workshop
A 60 m × 30 m workshop with an 8 m mounting height requires a maintained illuminance of 500 lux on the working plane. The existing installation has 120 high-bay metal-halide luminaires, each taking 440 W including the magnetic ballast, and operates 4,000 h per year.
638 words, about 3 min