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EV Electric Vehicles - Definitions

• The Tractive System (TS) includes every part electrically connected to the motor(s) and TS accumulators.
• TS enclosures refer to every container or housing for parts of the TS.
• Galvanic Isolation occurs when two electric circuits have a resistance ≥500 Ω/V related to the vehicle's maximum TS voltage, tested at the maximum TS voltage or 250 V (whichever is higher).
• Galvanic Isolation requires an isolation voltage RMS, AC for 1 minute, that is higher than three times the maximum TS voltage or 750 V (whichever is higher).
• The working voltage of the isolation barrier, if specified in the datasheet, must be higher than the maximum TS voltage for Galvanic Isolation.

Electric Powertrain

• Only electric motors are allowed.
• Motor attachments must adhere to T10 guidelines.
• Motor casings must adhere to T7.3 guidelines.
• The motors must connect to the accumulator via a motor controller.
• The TS power output at the outlet of the TSAC must not exceed 80 kW.
• Regenerating energy is allowed without restrictions.
• Wheels are prohibited from spinning in reverse.

General Requirements - Grounding

• TS enclosures must consist of a grounded solid layer of at least 0.5 mm thick electrically conductive material (aluminum or better).
• The grounded solid layer must have a resistance below 300 mΩ, measured with 1A, to LVS ground and it continuously carries at least 10% of the TS accumulator main fuse current rating.
• TS enclosures can be fully made of electrically insulating materials with ≥2ΜΩ isolation resistance, measured at 500V, must rigidly prevent mechanical penetrations, and any protruding conductive parts must follow EV3.1.2 guidelines.
• The TSAC may use a steel layer that is at least 0.9 mm thick as the grounded layer.
• Electrically conductive seat, driver harness, firewall mounting points, the aluminum layer of the TS firewall, and the LVS ground measuring point must have <300 mΩ resistance, measured with 1A, to LVS ground and it continuously carries at least 10% of the TS accumulator main fuse current rating.
• Parts of the vehicle that are or may become electrically conductive within 100 mm of any TS component must have <100Ω resistance to LVS ground.
• Rotating parts of the wheels cannot be grounded.

Overcurrent Protection

• All electrical systems must have proper overcurrent protection.
• Overcurrent protection's continuous current rating must not exceed the continuous current rating of the protected electrical component (e.g., wire, busbar).
• If multiple connector pins carry parallel currents, each pin must be appropriately protected.
• Overcurrent protection devices must have an interrupt current rating exceeding the system's theoretical short circuit current.
• Overcurrent protection devices must be rated for the system's highest voltage and be rated for DC.
• TS overcurrent protection devices cannot depend on programmable logic, but motor controllers/inverters may rely on programmable logic for the motor outputs' overcurrent protection.
• Overcurrent protection must function within the expected surrounding temperature range, but at least from 0°C to 85°C.
• The TS high current path through the accumulator(s) must be fused.

Tractive System (TS) - General Requirements

• The maximum permitted voltage between any two electrical connections is 600 V DC, 630 V DC for motor controller/inverters internal low energy control signals.
• All components in the TS must be rated for the maximum TS voltage.
• A TS area of a PCB is considered as one component, and every input connected to the TS must be rated to the maximum TS voltage.
• All components must be rated for the maximum achievable temperature during usage.
• Fans consuming >50W total power cannot connect to the TS.

TS System Enclosures

• TS enclosures must have reasonably sized sticker(s) that meet the "ISO 7010-W012" standard and the sticker needs to say “High Voltage” if the voltage is >60 V DC or 50 V AC RMS.

Separation of Traction System and Grounded Low Voltage System

• The entire TS and LVS are required to be is galvanically isolated.
• External devices connecting to a TS component, such as laptops, must include galvanic isolation.
• TS and LVS circuits must be physically separate, and cannot run through the same conduit or connector (excluding interlock circuit connections).
• TS and LVS within an enclosure must be separated by moisture-resistant, insulating barriers or maintain specific air or surface spacing.

Voltage Spacing Requirements

• U < 100 V DC requires 10 mm of spacing.
• 100 V DC < U < 200 V DC requires 20 mm of spacing.
• U > 200 V DC requires 30 mm of spacing.
• Components/cables that are capable of movement must be restrained positively to maintain spacing.
• TS and LVS on the same PCB require separate, well-defined areas meeting the spacing requirements. Each area needs to marked with either "TS" or "LV" and the outline is required to be marked.

Over Surface, Through Air and Conformal 1 Coating Spacing Based on Voltage

• 0 V DC to 50 V DC requires 1.6 mm Over Surface, 1.6 mm Through Air (Cut in Board), and 1.0 mm Conformal 1 Coating.
• 50 V DC to 150 V DC requires 6.4 mm Over Surface, 3.2 mm Through Air (Cut in Board), and 2.0 mm Conformal 1 Coating.
• 150 V DC to 300 V DC requires 9.5 mm Over Surface, 6.4 mm Through Air (Cut in Board), and 3.0 mm Conformal 1 Coating.
• 300 V DC to 600 V DC requires 12.7 mm Over Surface, 9.5 mm Through Air (Cut in Board), and 4.0 mm Conformal 1 Coating.
• "Conformal coating" refers to an insulation coating, not just solder resist.

Spacing Demonstrations

• Demonstrate spacing on team-built equipment.
• Provide assembled spare boards for inaccessible circuitry.

Positioning of Tractive System Parts

• All TS parts, including cables/wiring, must be within the rollover protection envelope
• All TS parts less than 350 mm above ground, impact protection is required.
• Impact protection needs to follow T3.16 with bolted attachments.
• TS wiring in front of the front hoop can be shielded by the front bulkhead support following T3.14, and the TSAC cannot be higher than the impact structure in EV5.5.1.

Outboard Wheel Motors are Allowed If:

• An interlock is routed along the TS wiring to open the shutdown circuit (EV6) before TS wiring or clamping fails.
• An interlock is routed along a suspension member to open the shutdown circuit (EV6) if the suspension fails.
• TS wiring cannot reach the cockpit opening or the driver if it breaks.
• Wiring outside the rollover protection envelope is minimum length.
• Wiring outside an impact structure or front bulkhead support structure is minimum length.
• Minimum length is the shortest distance plus extra wiring caused by bending radius.

Tractive System Insulation, Wiring and Conduit

• All live TS parts must be protected from touch, tested with a 100 mm long, 6 mm diameter insulated test probe with the TS enclosures in place, including for team members working on or inside the vehicle.
• Use insulation material rated for the maximum TS voltage because insulating tape or rubber-like paint is prohibited..
• TS wiring, connections, and insulation must have a temperature rating appropriate for the expected surrounding temperatures but at least 85°C.
• TS components and containers must be protected from moisture, e.g., rain or puddles

Wiring Standards

• Each wire's gauge, temperature rating, and insulation voltage must be clearly demonstrable.
• All TS wiring must be professionally completed with correctly sized conductors/terminals, adequate strain relief, and protection from loosening because of vibration.
• TS wiring must not be in the way of possible snagging or damage.

External TS Wiring Requirements

• It must be enclosed in separate orange non-conductive conduit or orange shielded cable, anchored securely to the vehicle (not to the wire) at each end.
• It must be securely anchored at each end to withstand 200 N without straining the cable end crimp.
• Bodywork alone is insufficient.
• Any shielded cable must have the shield grounded.
• Every external TS connector must have a pilot contact/interlock line as part of the shutdown circuit; housings used only to avoid interlocks are prohibited.
• TS connections must use intentional current paths through conductors (copper/aluminum) and cannot rely primarily on steel bolts.
• TS connections cannot include compressible materials (plastic) in the stack-up or as a fastener, but FR-4 is allowed.
• Screw type connectors inside the TSAC is allowed if part of an automotive grade OEM product or tested for appropriate vibrations.
• External TS connectors must prevent TS activation if connected in any way other than the design intent configuration.
• All electrical connections in the TS high current path is required to be secured from unintentional loosening with positive locking mechanisms suitable for high temperatures.
• Automotive grade components (e.g., inverters) may be allowed without positive locking if connections are completed per the manufacturer's datasheet and no positive locking is possible,.

Positive Locking

• Positive locking demonstrations are compulsory.
• Photographs are required for inaccessible connections.

Soldered Connections in High Current Path

• They're only allowed if connections are on PCBs.
• Soldered connections are forbidden on cells or wires
• Soldered connected devices are mechanically secured against loosening.

Data Logger

• Officials will provide a calibrated data logger to insert during competition to measure TS voltage and TS current.
• It is required to be easily accessible for insertion, removal, or replacement within 15 minutes during race conditions.
• It cannot placed inside the accumulator container.
• All current supplying the TS must pass through the data logger, and it must be located in the negative TS supply between the most negative AIR(s) and the inverters.
• The TS voltage sense connection of the data logger must be directly connected to the most positive AIR(s) on the vehicle side, and not carry any current.
• Direct supply for the data logger from the LVMS is required.
• The data logger specifications will be on the competition website.

Tractive System Measuring Point (TSMP) Requirements

• Two TSMPs must be installed directly next to the master switches.
• The TSMPs must directly connect circuit to the intermediate circuit capacitors, even if the HVD has been opened or the TS accumulator is disconnected.
• 4 mm shrouded banana jacks rated for 1000V CAT III or better must be used.
• The TSMPs are required to directly connecting to the positive and negative motor controller/inverter supply and must be marked “TS+” and “TS-” on an orange background.
• Protection for TSMPs using a non-conductive housing that opens without tools is required and the cover must be mechanically linked to the vehicle.
• Each TSMP needs securing with a current limiting resistor based on Maximum TS Voltage.
• Umax≤ 200 V DC*: 5 ΚΩ
• 200 V DC <Umax≤ 400 V DC*: 10 ΚΩ
• 400 V DC <Umax ≤ 600 V DC*: 15 ΚΩ
• All electrical connections for the TSMP require securing from unintentional loosening using positive locking mechanisms.
• Follow guidance T10.2 for bolted and EV4.5.16 for soldered connections.
• A 4 mm black shrouded banana jack must be connected to LVS ground, marked “GND”, and installed near the TSMPs.

High Voltage Disconnect (HVD) Requirements

• Must quickly disconnect at least one pole of the TS accumulator by removing an unobstructed element, fuse, or connector.
• The HVD must be disconnectable without removing any bodywork, be >350 mm above ground, and remote actuation (handle, rope, or wire) is prohibited.
• Any ESO must be able to remove the HVD within 10 seconds in race-ready condition.
• A dummy connector may need to restore the system's isolation, and be attached to the pushbar (T13.1) if not in use.
• The HVD has to have clear marking with “HVD”.
• The HVD needs no tools to open and needs interlock.

Discharge Requirements

• If a discharge circuit is required to meet EV6.1.5, it must be designed to handle the maximum tractive system voltage permanently.
• Exceeding discharge time in EV6.1.5 is possible following three discharges within 15s total.
• Full discharging functionality must be given after a reasonable time with deactivated circuit.
• The discharge MUST always be active whenever the shutdown circuit is open
• The intermediate circuit capacitors must be fail-safe, by discharging even if HVD opens/TS accumulator disconnects.
• Fusing is prohibited in the discharge main current path.
• No part of the discharge circuit can be inside the TSAC.

Tractive System Active Light (TSAL)

• Needs to indicate the TS status, with multiple LEDs in one housing allowed,.
• The TSAL itself must have a red light that flashes continuously from 2-5 Hz with a 50% duty cycle. It must be active if the LVS is active and the voltage across DC-link capacitors exceeds 60 VDC / 50 VAC RMS or half of the nominal TS voltage (whichever is lower).

Green Light

• A green light is needed, continuously on, active if the LVS is active and ALL conditions that follow are true:
• AIRs are opened.
• The pre-charge relay (EV5.7.2) is opened.
• The voltage at the vehicle side of the AIRs inside the TSAC does not exceed 60 VDC or 50 VAC RMS.
• The mentioned voltage detection must be performed inside the respective TS enclosure.
• The mentioned states of the relays are the actual mechanical states. Any circuitry detecting the mechanical state must meet EV5.6.2, as it can differ from intentional state .

The TSAL

• It is required to be lower than the highest point of the main hoop and within the rollover protection envelope.
• It needs to be no lower than 75 mm from the main hoop's highest point.
• It needs to not contact the driver's helmet in any circumstances.
• The entire illuminated surface must be clearly visible, except at angles <10° blocked by the main hoop., from 1.60 m vertically from ground level within 3 m horizontal radius, and in direct sunlight.

The TSAL and Software

• The TSAL and all needed circuitry requires hard wired electronics.
• Software control is not permitted.
• A green indicator light in the cockpit must be visible (even in bright sun) and clearly marked with "TS off" should light up if the TSAL green light is on.
• Signals influencing the TSAL/indicator must be SCS, and an active indication of absence of failures should be observed.
• The TSAL's red light voltage detection circuit needs SCS Check and turn TSAL's red light off in sensor failure cases.
• A TSAL green light must enter a safe state,
• If* TSAL's green light relay state detection circuit detects implausibility between the intentional/mechanical state of the relay (AIR/Precharge). If a TSAL's green light voltage detection circuit detects implausibility, as required by T11.9.2(b).
• A latching circuit is required to latch safe state and must only be reset by power-cycling the LVS..

Tractive System - Activation

• The TS is considered active if any AIR or the pre-charge relay is closed.
• The driver must be able to activate/deactivate the TS from within the cockpit alone.
• Closing of the shutdown by any part does not re-activate. Additional action is needed.
• The vehicle is ready to drive as soon as the motor(s) responds to APPS input.
• After activation, additional actions by the driver is required to enter ready-to-drive mode (e.g. pressing a dedicated start button).
• Transition is permitted during the actuation of mechanical brakes with a simultaneous dedicated additional action.
• The ready-to-drive mode ends immediately when the shutdown circuit opens.

Ready-To-Drive Sound

• Vehicle should make a characteristic sound lasting from at least 1 to 3 seconds while the vehicle is entering R2D mode
• A sound level that is >80 dBA but <90 dBA is allowable, sound that are parts of song, animal voices, and offensive sound are not
• The vehicle may not output any similar sound to ready-to-drive-sound while not in R2D mode

Tractive System Energy Storage - Definitions

• Cell refers to a battery cell or super-capacitor.
• Cell Energy is the product of the maximum cell voltage and the nominal capacity of the used cell.
• TS Accumulator includes all cells storing electrical energy for the TS.
• TS Accumulator Container (TSAC) is a container housing the TS accumulator.
• TS Accumulator Segments are subdivisions of the TS accumulator.

Tractive System Accumulators

• All accumulator types (except molten salt and thermal batteries) are allowed.
• Fuel cells are prohibited.
• All cells that store TS energy must be in (an) accumulator container(s).
• Each accumulator segment is required to not exceed a 120V DC maximum static voltage, with a maximum energy of 6 MJ and a maximum mass of 12 kg.
• All the spare TS accumulators have to be of the same size and weight, and will undergo a technical inspection similar to the non spare accumulators.
• Spare cells are to be electrically insulated and stored in a fire retardant container (see T1.2.1); the container should be labeled properly
• Both accumulators and spare cells needs to be openable for the technician, and removable without extra components and comply with the set of rules

TSAC

• All vehicle numbers must include the university and the ESO phone number(s), as well as the cell chemistry and TS voltage
• Should be at least 20 millimeters in height, should be easily visible, and has to have a high-contrast backing behind

Electrical Configuration - Tractive System Energy Storage

• Any conductive material or contact must have the insulation barrier be adequately protected by something conducive
• Requires minimum one fuse
• At least two AIRs
• If an LVS isn't a requirement, then it cannot be used inside the TSAC
• Maintenance plugs require electrical removal if they exceed the 5.3.2 regulations

Electrical Configuration - Maintenance Plugs Require:

• A requirement to not need tools to extract and move the TSAC parts
• In order to not induce a voltage between TSAC parts, use a non-conductive material, and must not induce any voltage at the AIR upon removal.
• Each section must use a fire-retardant and approved insulators to ensure proper insulation
• Wires used in the TSAC has to be made by an approved conductor

Safety and TSAC

• Each TSAC has to have a voltmeter with an LED indicator that displays if voltage is greater than 60V DC or half the nominal voltage
• Indicator has to show the vehicle that it is disconnected
• Any indicator should be connected without the use of a software
• Powered by a TS power source, and be able to remove power source by the AMS switch

Mechanical Configuration - Tractive System Energy Storage

• Each TSAC must be held to the primary structure
• Impact protection is required
• Materials used should be fire-retardant, made to calculate under an ambient temperature of 60 Degree C, with materials that comply with the EV5.5 regulations