Electrical & Electronic Systems Flashcards
7 cards from real LEC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical & Electronic Systems flashcards as text
What is the purpose of the 'transition' function in older DC traction locomotive electrical systems?
Answer: Switch traction motors from series to parallel configuration to optimize power at higher speeds
Transition reconnects traction motors from series (high torque, low speed) to parallel (higher speed) configurations, optimizing power delivery across the speed range.
Which federal regulation governs locomotive safety standards, including electrical system requirements, for US railroads?
Answer: 49 CFR Part 229 (Railroad Locomotive Safety Standards)
49 CFR Part 229 establishes FRA safety standards for railroad locomotives, including requirements for electrical systems, lighting, and control equipment.
A locomotive's traction motor shows signs of flashover. What is a flashover?
Answer: An electrical arc between commutator bars or between brush and commutator in a DC motor
A flashover is a disruptive electrical arc that jumps between commutator segments or between brushes and the commutator in a DC traction motor, potentially causing serious damage.
What is the role of the 'throttle resolver' or throttle position sensor in an electronically controlled locomotive?
Answer: Convert the engineer's throttle handle position into an electronic signal for the control system
The throttle resolver converts the mechanical position of the throttle handle into an electronic signal that the locomotive's control system uses to set power output.
What condition is indicated when a locomotive's ammeter shows zero current while operating in a power notch?
Answer: A possible open circuit in the traction motor or power circuit
Zero ammeter reading under a power notch typically indicates an open circuit fault, such as a blown fuse, open contactor, or failed motor, preventing current flow.
Which component prevents excessive voltage from reaching sensitive electronic control equipment on a locomotive?
Answer: Transient voltage surge suppressor (TVSS) or surge arrestor
Transient voltage surge suppressors (TVSS) or surge arrestors clamp voltage spikes to safe levels, protecting sensitive electronic cab and control equipment from damage.
What is the purpose of 'wheel creep control' in modern AC traction locomotive systems?
Answer: Maintain a small, controlled amount of wheel slip to maximize tractive effort at the adhesion limit
Wheel creep control intentionally maintains a slight, optimized slip ratio between wheel and rail, which maximizes tractive effort by operating at the peak of the adhesion curve.