Solar Car Challenge Rule 5.4.5 provides specific requirements for the Emergency Disconnects used on solar cars. After reviewing team registration documents, several teams are not using the required "red knob" push-pull disconnects.

Please double-check your disconnect switches. Solenoids and other disconnecting devices will not work. This is not a penalty offense .... it is a disqualification offense.

It is crucial that both the team and emergency response staff be able to quickly disconnect your electrical system using uniform cut-offs. A sample approved disconnect is attached.

RULE 5.4.5

Disconnect Switches - Solar cars must have "kill" switches wired to disconnect all power to the motor and solar array. A total of four disconnect switches are required - two each to interrupt current to the motor and array. One set of motor and array disconnects shall be accessible by the driver, within arm’s reach, and another set shall be accessible by bystanders external to the vehicle. Each disconnect must be capable of carrying and interrupting the full load current at system voltage. Disconnects must be manually operated and shall not operate a separate contact, relay, or solenoid switch.

(a) Disconnect switches must be push-pull, where the circuit is broken when the disconnect switch is pushed in.

(b) Disconnect Switches must be clearly labeled in 10mm-high letters, and be plainly marked with "ON" and "OFF" positions. Motor disconnect switches shall be labeled "Motor Disconnect" and array disconnect switches shall be labeled "Array Disconnect" Switches shall be labeled with the directions for operating the switch, such as "Push for Off."

(c) Manufacturer documentation must be provided for all disconnect switches and show that the devices being utilized are rated properly.

(d) Disconnect switches must be securely fastened to the vehicle structure to prevent failure in emergency situations.

(e) Disconnect switches must be in plain sight by a bystander in standing position and may not be hidden under panels.

(f) Disconnect switches must be in series with no other devices or connections between them. The motor disconnect shall be placed first in series on the positive connection to the motor controller. The array disconnect shall be placed first in series on the positive connection to the solar panels or solar array power trackers, if used.

Attachment: Disconnect Switch.pdf

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