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These 10 free EGSTC-J questions are organized by exam domain, so you can see how each part of the Electrical Generator Systems Technician Certification - Journeyman (EGSTC-J) blueprint is tested. Reveal the answer and explanation under each question.
A temporary feeder has a permitted continuous current of 220 A after all applicable corrections. The proposed balanced, sinusoidal three-phase test load is 144 kW at 480 V line-to-line and 0.75 power factor. All other connection requirements are satisfied. Which assessment of the feeder is correct?
Correct answer: D - Inadequate: the expected line current is about 231 A.
"The load is below the set's kW rating, so we can add more." A 400 kW/500 kVA generator set is operating at rated voltage and frequency, with a balanced load measuring 320 kW and 525 kVA. Does the unused kW capacity justify adding load?
Correct answer: D - Reject it; the apparent-power limit is exceeded despite the unused kW capacity.
An isolated generator develops excessive terminal voltage while shaft speed and the AVR's power supply remain normal. Recorded tests show zero voltage at the AVR's voltage-sensing input. The regulator has no effective loss-of-sensing protection. What response of the AVR's voltage-control loop explains the overvoltage?
Correct answer: C - Zero feedback appears below the voltage reference, so the AVR increases excitation to correct the apparent undervoltage.
An enclosed generator approaches its coolant-temperature limit at rated load. Outside air is 34°C, but air entering the radiator is 49°C. During an approved test, a temporary diverter redirects radiator discharge away from the enclosure intake. At the same load, radiator inlet air falls to 36°C and coolant temperature stabilizes safely below the limit. Which permanent repair does this result support?
Correct answer: A - Correct enclosure airflow to prevent radiator discharge from returning to the intake.
During investigation of repeated low-oil-pressure shutdowns, the last readings before one shutdown are 55 psi on a calibrated gauge at the same oil gallery as the pressure transmitter, 0 psi on the controller, and 0 mA in the transmitter loop. The specified running-pressure range is 40-70 psi. With the engine stopped, direct input simulation at 4, 12, and 20 mA produces the correct 0, 50, and 100 psi displays. Where should the repair effort now be directed?
Correct answer: B - Test the transmitter, loop supply, and field wiring.
On a stiff utility bus, increasing a paralleled generator's governor power command raises its output from 220 kW to 310 kW, within the authorized test range. Frequency stays at 60 Hz and reactive output remains near 45 kvar. A technician calls the unchanged speed evidence of a governor failure. The appropriate explanation is:
Correct answer: D - Normal: the utility constrains frequency while added engine input increases kW.
Since a generator was replaced, load-dependent current has appeared on its equipment grounding conductor. The ATS switches only the three phase conductors; the neutral remains solidly connected to the service. The approved drawing shows the sole neutral-to-ground bond at the service, but the replacement generator also has a bonding jumper installed. No phase-to-ground insulation fault is found. With the equipment isolated for correction, which change restores the specified bonding arrangement?
Correct answer: B - Remove the added generator bonding jumper.
Two equally rated generators share an isolated 480 V, 60 Hz bus. Verified meters show 300 kW from each set, but Generator A supplies 140 kvar while Generator B absorbs 20 kvar, displayed as -20 kvar. Voltage and frequency are steady. How should these readings be interpreted?
Correct answer: C - The kW sharing is balanced; investigate excitation references and reactive-sharing circuits.
A 12 V starting system cranks slowly. During cranking, the service limits are at least 9.6 V across the battery posts and no more than 0.5 V drop through either cable path. Measurements are 10.6 V across the battery, 2.4 V from battery-positive to starter-positive, and 0.2 V from starter case to battery-negative. The excessive voltage loss is in:
Correct answer: A - The positive cable and its connections.
A 155 kW commissioning load is required on a 400 V generator with sufficient capacity. The available fixed-resistance bank is rated 180 kW at 480 V. Its manufacturer permits this 400 V connection, including the fan and control supplies, without changing the resistor connections. Can the bank deliver the required load with all stages selected?
Correct answer: A - No; it will apply 125 kW, leaving a 30 kW shortfall.
The EGSTC-J exam also covers these domains. Drill them in the full free practice test:
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