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EV.5.5 High Voltage Disconnect - HVD
A High Voltage Disconnect (HVD) must be included to quickly disconnect one or both poles of the Accumulator EV.11.3.2
EV.5.5.1 The High Voltage Disconnect (HVD) must be:
a. A directly accessible element, fuse or connector
b. More than 350 mm from the ground
c. Easily visible when standing behind the vehicle
d. Operable in 10 seconds or less by an untrained person
e. Operable without removing any bodywork or obstruction or using tools
f. Directly operated. Remote operation through a long handle, rope or wire is not
acceptable.
g. Clearly marked with "HVD"
A High Voltage Disconnect (HVD) is designed to safely isolate high-energy circuitry from its power source, which is necessary for emergencies such as faults or overcurrent situations. These disconnects often incorporate mechanical and electrical interlocks to prevent accidental operation, enhancing the overall system safety and reliability.
As stipulated in EV.11.3.2, the HVD must be disconnected when the vehicle is in transit around the competition site, as well as participating in Static Events.
Rules Reference - EV.11.3.2
Rules Reference - EV.11.3.2
EV.11.3.2 The HVD EV.5.5 must be disconnected when vehicles are:
a. Moved around the competition site
b. Participating in Static Events
EV.5.5.1.a requires that, for ease of access, the component can be easily reached or touched without the need for special tools, equipment, or the removal of barriers. Additionally, as per EV.5.5.1.b, the disconnect must not be located close to the ground (within 350 millimeters) to reduce the risk of accidental contact between grounded objects or surfaces. This contact can create a path for current to flow, potentially causing arcing if:
The disconnect is operated under load
There is an abundance of dirt, moisture, and debris near ground level
The insulation has degraded as a result of environmental factors
EV.5.5.1.c states that the disconnect should be visible and accessible from the back of the vehicle. This may be as a result of visibility being obstructed by frontal components such as the Impact Attenuator, Body Panels, and Firewall. Ultimately, the view of critical safety components such as the HVD should be unobstructed. EV.5.5.1.d, EV.5.5.1.e, and EV.5.5.1.f require that any passerby be able to operate it in less than ten seconds, that it be unobstructed by bodywork or components that would need to be removed with tools, and that it is directly actuated (otherwise, there would be risk of an in-between component failing). Finally, EV.5.5.1.g requires that the component be marked HVD to ensure that across all team's cars, it is accessible and visible in case of emergency.
Video - HVD Disconnected
Video - HVD Disconnected
vid2.movVideo - HVD Reconnect
Video - HVD Reconnect
vid1An Interlock is described in EV.7.8, and a synopsis of its specifications are as follows:
Interlocks must be embedded within the HVD, Tractive System Connectors outside of a housing, and specific cases of Outboard Wheel Motors as per EV.7.8.1, but can be used in additional components not specified as stated in EV.7.8.2.
From EV.7.8.3.a, an Interlock is defined as a wire or connection which, if interrupted, opens the Shutdown Circuit. This connection should be distinct from the ground connection to the Accumulator Isolation Relay Coils, as stated in EV.7.8.3.b. These connections do not require physical separation form the Tractive System Wiring or components (per EV.7.8.4) because they engineered to function effectively without requiring physical separation from high voltage components. They are designed with safety features, efficiency considerations, and compliance with standards in mind to ensure they operate reliably within the electrical system they are meant to protect.
Rules Reference - EV.7.8
Rules Reference - EV.7.8
EV.7.8 Interlocks
EV.7.8.1 Interlocks must be incorporated where specified (refer to EV.4.1.3, EV.5.5.2, EV.5.10 )
EV.7.8.2 Additional Interlocks may be included in the Tractive System or components
EV.7.8.3 The Interlock is a wire or connection that must:
a. Open the Shutdown Circuit EV.7.2.2 if the Interlock connection is broken or interrupted
b. Not be in the low (ground) connection to the AIR coils of the Shutdown Circuit
EV.7.8.4 Interlock circuits or connections do not require physical separation (EV.6.5) from Tractive System wiring or components
Rules Reference - EV.4.1.3 (Referenced in EV.7.8)
Rules Reference - EV.4.1.3 (Referenced in EV.7.8)
EV.4.1.3 If used, Outboard Wheel Motors, where the motor, attendant cables and wiring do not meet F.11.1.3, must:
a. Include an Interlock EV.7.8
This Interlock(s) must Open the Shutdown Circuit EV.7.2.2 before failure of the Tractive System wiring when the wiring is damaged or the Wheel/Motor assembly is damaged or knocked off the vehicle.
b. Reduce the length of the portions of wiring and other connections that do not meet F.11.1.3 to the extent possible
Rules Reference - EV.5.10 (Referenced in EV.7.8)
Rules Reference - EV.5.10 (Referenced in EV.7.8)
EV.5.10 Connectors
Tractive System connectors outside of a housing must meet one of the two:
Contain an Interlock EV.7.8 which must Open the Shutdown Circuit EV.7.2.2
Be sealed at Tech Inspection IN.4.7.1
Rules Reference - EV.7.2.2
Rules Reference - EV.7.2.2
EV.7.2.2 When the Shutdown Circuit Opens:
a. The Tractive System must Shutdown
b. All Accumulator current flow must stop immediately EV.5.4.3
c. The voltage in the Tractive System must be Low Voltage T.9.1.2 in five seconds or less
d. The Motor(s) must spin free. Torque must not be applied to the Motor(s)
According to EV.7.2.2, opening the Shutdown Circuit requires that components within the Tractive Path must be shut down. Additionally, current flow must stop within the Accumulator and the Accumulator Isolation Relay (AIR) Coils must be engaged. As stated in EV.5.4.3, the Accumulator Isolation Relays are of the Normally Open Type, so in the non-energized state, there should be no High Voltage outside of the Accumulator Container.
Additionally, the Tractive system, within five seconds of the Shutdown Circuit engaging, must be read on a multimeter as Low Voltage, which, stated in T.9.1.2 is defined as DC voltage less than 60V, or AC voltage less than 25VRMS. Additionally, torque cannot be applied to slow down or speed up the motor(s).
Reference Rule - T.9.1.2 (Referenced in EV.7.2.2)
Reference Rule - T.9.1.2 (Referenced in EV.7.2.2)
T.9.1.2 Low Voltage - LV
Any voltage less than and including 60 V DC or 25 V AC RMS
Rules Reference - EV.5.4.3 (Referenced in EV.7.2.2)
Rules Reference - EV.5.4.3 (Referenced in EV.7.2.2)
EV.5.4 Accumulator Isolation Relays - AIR
EV.5.4.3 When the AIRs are open, High Voltage T.9.1.1 must not be external of the Accumulator Container
EV.5.5.3 A dummy connector or similar may be used to restore isolation to meet EV.6.1.2
Teams may need to insert a dummy connector to prevent exposure of HV terminals while performing maintenance on High Voltage (HV) systems within the car, manually pushing the vehicle, charging, or at competition until Technical Inspection is passed.
Referenced in this rule, EV.6.1.2 stipulates that while the Tractive System enclosures are in place, a predefined test probe should not be able to make contact with exposed connections.
Rules Reference - EV.6.1.2
Rules Reference - EV.6.1.2
EV.6.1.2 Contact with any Tractive System connections with a 100 mm long, 6 mm diameter insulated test probe must not be possible when the Tractive System enclosures are in place.
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