High Voltage Electrical Systems & Wiring Flashcards
7 cards from real EVT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 High Voltage Electrical Systems & Wiring flashcards as text
What does the abbreviation HVIL stand for in electric vehicle high-voltage systems?
Answer: High Voltage Interlock Loop
HVIL stands for High Voltage Interlock Loop, a safety circuit that detects when HV covers or connectors are opened and commands the BMS to open the main contactors.
What happens to the high-voltage system when the HVIL circuit is broken?
Answer: The BMS opens the main contactors, de-energizing the HV bus
When the HVIL circuit is broken by opening a cover or connector, the BMS interprets this as a safety event and opens the main contactors to de-energize the HV bus.
Why are high-voltage cables in EVs typically shielded with a metallic braid or foil?
Answer: To reduce electromagnetic interference (EMI) radiated by HV cables
Metallic shielding on HV cables reduces EMI emissions from the high-current, high-frequency switching signals, protecting sensitive vehicle electronics and meeting regulatory requirements.
What test voltage is typically applied by a megohmmeter when testing insulation resistance on EV high-voltage circuits?
Answer: 500V DC
A 500V DC test voltage is standard for insulation resistance testing on EV HV circuits, providing enough stress to reveal insulation weaknesses without over-stressing good insulation.
Which international standard defines electrical safety requirements for electric road vehicles, including HV wiring protection?
Answer: ISO 6469
ISO 6469 is the international standard specifying electrical safety requirements for electrically propelled road vehicles, covering HV wiring, isolation, and protection measures.
What is the function of shorting caps on high-voltage connectors in EV service procedures?
Answer: They short the connector pins together when disconnected to discharge residual capacitive charge
Shorting caps short the HV connector pins together when disconnected, safely discharging residual capacitive energy and preventing accidental shock to the technician.
In EV high-voltage circuit diagrams, how are main contactors typically represented?
Answer: As a normally-open switch symbol controlled by a relay coil
Main contactors are represented as normally-open relay-controlled switches, showing that they require an energized coil to close and allow HV current to flow.