System Critical Signals (SCS) and Failure handling

• System Critical Signals (SCS) refer to all electrical signals influencing the shutdown circuit, wheel torque and indicators.
• Any SCS failures must lead to a safe state for all connected systems.

Failures of transmitted signals by cable:

• Open circuit
• Short circuit to ground

Failures of analog sensor signals transmitted by cable:

• Short circuit to supply voltage

Failures of sensor signals used in programmable devices:

• Implausibility from out-of-range signals, like a mechanically impossible angle of an angle sensor.

Failures of digitally transmitted signals via cable or wireless:

• Data corruption, checked by a checksum

• Loss and delay of messages, checked by transmission time outs

• Signals might belong to multiple signal classes like T11.9.2.a, T11.9.2.b, and T11.9.2.c

• If a signal failure is correctable, the safe state must be entered after an additional non-correctable failure occurs.

• The maximum allowed delay of messages according to T11.9.2.d must be chosen to account for the impact of delayed messages and cannot go over 500ms.

• The safe state is signal-dependent.

• Signals influencing indicators signify a failure in their own function or the connected system.

• Low voltage battery signals have at least one pole electrically disconnected from the rest of the vehicle.

• Open shutdown circuit and opened AIRs for all other signals in EV ONLY.

• Open shutdown circuit and stopped engine for all other signals in CV ONLY.

• Indicators under T11.9.1 with "illuminated" safe state needing illumination for 1s to 3s post LVMS power cycle for visible check.

Accelerator Pedal Position Sensor (APPS)

• Pedal travel is defined as the percentage from fully released (0%) to fully applied (100%) position.
• The foot pedal must return to 0% when not actuated; it must have a positive stop protecting sensors from damage.
• Return achieved using two springs, each functional independently; using springs in the APPS is unaccepted
• Using at least two separate sensors, sensors may share housing
• Analog sensors used must have different transfer functions so that a short circuit is always implausible per T11.8.9.
• Implausibility between APPS values persisting over 100ms must cause immediate shutdown of the motor, with the controllers powering the motor.
• Definition of implausibility is above 10% of pedal travel between any APPS sensors or failure according to T11.9
• If three sensors used, plausible ones can define torque target; non-plausible ones may be ignored.
• Each APPS signal wire must be disconnectable to check functionalities.
• Fully released accelerator pedal must result in torque of ≤0 N m for EV ONLY.
• Results in an idle position or lower throttle set-point; May only be exceeded during a gearshift for a maximum of 500ms for CV ONLY.

Brake System Plausibility Device (BSPD)

• A standalone, non-programmable circuit, the BSPD, must open the shutdown circuit when hard braking occurs.
• It must occur when ≥5 kW power is delivered to motors for EV ONLY.
• It must occur when the throttle position is more than 25% over idle position for CV ONLY.
• The shutdown circuit must remain open until either LVMS power cycling or the BSPD resets itself following an opening condition over 10 s
• It initiates action if implausibility persists for over 500 ms.
• The BSPD must be supplied directly from the LVMS
• Standalone means only essential interfaces are implemented.
• Interfaces include: power supply, sensors and the shutdown circuit.
• The supply and sensor signals should not be routed through other devices beforehand.
• Brake system pressure sensor needed, threshold chosen to avoid locked wheels at ≤ 30 bar.
• Power delivery measurement requires a DC circuit current sensor; the threshold is ≤5 kW for max TS voltage for EV ONLY.
• All sensor signal wires should be disconnectable for technical inspection.
• All signals the System Critical Signal (SCS), as per T11.9.
• During technical inspection, the function of BSPD must be proven by team sending signal representing the current.
• The current must achieve ≤ 5 kW while brake pedal being pressed; This process must showcase the full BSPDs functionality, aside from available commercial current sensors.

Inertia switch

• The intetia switch needs to be part of the shutdown circuit and activated in the event of impact, and the shutdown circuit has to be opened
• It must latch until manually reset
• It must trigger given omni-directional peak acceleration of ≤8 g (≥50 ms half sine test pulse), or ≤13 g (≥20 ms half sine test pulse).
• Resettable crash sensor must meet these requirements.
• The device cannot include semi-conductor components
• The device must be rigidly attached to the vehicle and its functionality must be tested by shaking it
• The inertia switch should be acting directly and external relay circuits are prohibited

Low Voltage System (LVS)

• Definition: all electrical circuits of the vehicle for CV ONLY.
• Definition: every electrical part not of the TS for EV ONLY.
• Maximum permitted voltage: 60 V DC or 50 V AC RMS.
• All LVS parts must be adequately insulated.
• Excluded from LVS voltage limit for CV ONLY: high voltage systems for ignition/injectors and voltages internal to OEM charging systems designed <60 V DC output.
• No orange wiring or conduit for EV ONLY.
• LVS must be grounded to chassis for EV ONLY.

LV Batteries

• LV batteries are connected to the LVS.

• LV batteries must be securely attached to the chassis and within the rollover protection envelope.

• Any wet-cell battery within the driver compartment should be inside a non-conductive, waterproof container per IPX7 (or higher, IEC 60529) and acid resistant container.

• LV batteries must have a rigid and sturdy casing for EV ONLY:

• The enclosure should be fire retardant.

• Must comply with EV4.5.1.

• If in the TS loadpath, must comply with EV5.5.9.

• Closed LV battery cases must have an overpressure relief; venting gases must be separated from the driver through firewall.

• Ungrounded terminals must be insulated.

• LV batteries must be protected from short circuits, at most 100 mm from ungrounded terminals.

• For battery packs using lithium chemistry, they must:

• Have a fire retardant casing.

• Include overcurrent protection that trips below max discharge current.

• Include over temperature protection of at least 30% of the cells, meeting EV5.8.3.

• Protection is needed to trip for any cell that leaves the approved range (according to datasheet and not more than 60°C for more than 1 s)

• Must include voltage protection of all cells, which will trip when cells leave the approved voltage range (according to the datasheet for more than 500 ms and disconnects the battery)

• display all cell voltages and measured temperatures.

• meet EV5.8.10.

• Signals for all requirements are SCS.

• The BSPD (with required sensors) cannot be installed inside the accumulator container for EV ONLY

• Master switches must be a mechanical switch of the rotary type (See T11.3 and EV6.2)

• Master switches must have a red, removable handle and be directly acting, i.e. they must not act through a relay or logic.

• The handle itself should have a minimum width of 50 mm and be only removable when in an electrically open position

• The handle must have a visible car number

• Master switches are on the vehicle's right side, close to the main hoop, at male driver's shoulder height and easily actuated externally.

• The center of any master switch can't be lower than 0.8 times the vertical distance from the template's middle circle to the ground (see T4.3)

• The "ON" position needs to be in a horizontal orientation and marked appropriately, so does the "OFF" position do

• Master switches should be rigidly attached and must not be removed when in maintenance (EV ONLY)

• Master switches must be mounted close to one another (EV ONLY)

Low Voltage Master Switch (LVMS)

• The LVMS must disable power to the LVS for EV ONLY.

• The LVMS must disable power to power from the low voltage (LV) battery and alternator to the LVS for CV ONLY.

• To comply with T11.2 the LVMS must be marked with "LV" and a white-edged blue triangle spark in a red circle

• The LVMS must be mounted in at least 50mm circular red area and be set against a high contrast background

• A system of three shutdown buttons must be installed.

• Each such button must be a push-pull/push-rotate mechanical emergency switch, opening the shutdown circuit upon push.

• One button is located on either side of the vehicle behind the driver; the remaining button can be used as a cockpit-mounted shutdown button

• Buttons alongside the vehicle and on sides of the drivers compartment must be at least 40 mm, should be reachable and be located horizontally

• One cockpit-mounted shutdown button must

• Have at least 24 mm diam.

• Located within reach of belted-in driver.

• Beside steering wheel/unobstructed by it; or anything else within the vehicle

• All shutdown buttons must include affixed in close proximity The international electrical symbol (a red spark) set against a white-edged blue triangle

• All shutdown buttons should have a rigid attachment to the mounting without any ability to be removed during maintenance

• All shutdown buttons must be red