EVT Charging Systems & Infrastructure Flashcards

A Tesla vehicle using a J1772 adapter shows a charging fault. The technician measures CP at +12V DC (no PWM). What does this indicate?

Answer: EVSE is in standby waiting for vehicle connection

A steady +12V DC on the CP line (no PWM) is the J1772 State A condition, meaning the EVSE is in standby and not detecting a connected vehicle.

What is the purpose of the Proximity Pilot (PP) pin in a Type 1 (J1772) connector?

Answer: Detects connector latch state and signals vehicle to limit torque before unplug

The Proximity Pilot tells the vehicle the connector is attached and prevents the drivetrain from engaging while plugged in, protecting the cable and inlet.

Which organization certifies EVSE installations under the UL 2594 standard for EV supply equipment safety?

Answer: Underwriters Laboratories (UL)

UL 2594 is the standard developed and administered by Underwriters Laboratories for the safety certification of EV supply equipment.

A technician is installing a 50A, 240V Level 2 EVSE circuit. Per NEC Article 625, the circuit must be rated at no less than what percentage above the continuous load?

Answer: 125%

NEC requires EVSE circuits to be sized at 125% of the continuous load because EV charging is considered a continuous load (operating for 3+ hours).

What is 'V2G' technology in the context of EV charging infrastructure?

Answer: Vehicle-to-Grid: bidirectional power flow from EV battery back to utility grid

V2G (Vehicle-to-Grid) allows a bidirectional charger to export stored energy from the EV battery back to the electrical grid for demand response or energy arbitrage.

When commissioning a new DC fast charger, a technician must verify insulation resistance between the high-voltage DC output and the charger chassis. What minimum resistance value is generally acceptable?

Answer: 1 MΩ

A minimum of 1 MΩ insulation resistance between HV conductors and chassis is the commonly accepted threshold; values below this indicate insulation degradation.