LEC Electrical & Electronic Systems 3

Question 1

What is the voltage range typically used for battery systems on a modern diesel-electric freight locomotive?

Accepted Answer

64–74 volts DC

Answer

Most diesel-electric freight locomotives use a 64–74 volt DC battery system to power starting circuits, control systems, and lighting when the engine is off.

Question 2

An engineer notices the 'low oil pressure' light illuminating while running at full throttle. What is the correct initial response?

Accepted Answer

Reduce throttle and notify dispatch while monitoring the situation

Answer

Reducing throttle decreases engine load while monitoring oil pressure; the engineer should notify dispatch and follow railroad procedures to protect the prime mover.

Question 3

What is the function of the load regulator on a diesel-electric locomotive?

Accepted Answer

Controls fuel delivery to maintain constant engine RPM under varying loads

Answer

The load regulator adjusts the electrical load on the main alternator to maintain constant engine RPM regardless of traction power demands.

Question 4

Which system on a locomotive continuously monitors axle bearing temperatures and alerts the crew to overheating?

Accepted Answer

Onboard bearing temperature monitoring system

Answer

The onboard bearing temperature monitoring system uses sensors on each axle to detect abnormal heat and alert the engineer before a hotbox failure occurs.

Question 5

A locomotive's electrical system shows repeated tripping of the same circuit breaker. What should the engineer do?

Accepted Answer

Reset once; if it trips again, leave it open and report it

Answer

Resetting a circuit breaker once is permitted; if it trips again, leaving it open prevents fire or further damage, and the fault must be reported.

(LEC) Locomotive Engineer Certification Practice Test

(LEC) Locomotive Engineer Certification Practice Test

LEC Electrical & Electronic Systems 3