Engineer Electric Work case studies
Engineer Electric Work · Put your knowledge to work in context.
The Engineer, Electric Work credential is a professional engineering certification for practitioners who design, supervise, and take responsibility for electrical installations and power systems. It suits licensed engineers, senior electrical designers, plant and utility engineers, and consultants who must sign off on work where safety, code compliance, and system reliability are at stake. The Engineer Electric Work case studies are 5 cases and about 4,374 words.
1Nuisance 87T Trips After a CT Replacement on a 5 MVA Transformer
A 5 MVA, 26.4/4.16 kV, Dyn1 transformer feeds a 4.16 kV switchgear lineup. The 87T relay uses 600/5 CTs on the 4.16 kV side and 200/5 CTs on the 26.4 kV side; the relay's ratio and vector-group compensation settings were verified as correct.
919 words, about 5 min2Rewound 300 hp Motor Running Hot With Voltage Unbalance and a 21 °C Phase Spread
A 300 hp, 460 V, 4-pole, 60 Hz TEFC motor (355 A FLA, 1.15 service factor, Class F, rated 40 °C ambient) drives a critical cooling-water pump. After a rewind by a local shop the motor draws 342 A and its three stator RTDs stabilize at 158, 141 and 137 °C; the shop's report shows 1.2 GΩ insulation resistance and a 'satisfactory' surge comparison test.
878 words, about 4 min3Sizing a 160 m Chiller Feeder Through a 45 °C Boiler Room in a Shared Tray
A 320 A continuous, 480 V, three-phase, three-wire chiller (pf 0.90) is to be fed from an MCC 160 m away on a covered cable tray that already carries two other three-phase circuits, so the chiller's conductors will be part of a six current-carrying-conductor group. The route passes through a boiler room where the ambient is 45 °C.
772 words, about 4 min4Series Rating, Selective Coordination and a Stale Arc Flash Label on a Hospital Essential System
A 320-bed hospital is adding a 500 kW chiller to its essential electrical system (EES). The chiller is fed from a new 400 A ATS connected to a spare 400 A breaker in the 480 V main switchboard, which has a 2,000 A main and a series rating of 65 kA marked for the listed main/branch combinations; available fault current at the board is 41 kA.
930 words, about 5 min5Substitution Pressure, Liquidated Damages and a Field Certification You Cannot Honestly Sign
You are the engineer of record for a 69/13.8 kV substation upgrade for a municipal utility. The contractor's submittal offers 15 kV metal-clad switchgear rated 25 kA instead of the specified 31.5 kA, with no NRTL listing mark, stamped by a PE licensed in another state and annotated 'equal, subject to engineer's review.' The utility's fault study gives 28.5 kA at the 13.8 kV bus.
875 words, about 4 min