EV.5.9 Tractive System Active Light - TSAL

The Tractive System Active Lighting (TSAL) is a non-programmable circuit board that monitors for cases of High Voltage outside of the Accumulator(s). This circuit only has two functions (as stated by EV.5.9.1.c): it must illuminate (power a specific type of LED) when the Grounded Low Voltage System is active, and change color to indicate whether the High Voltage Tractive System is active or inactive as per EV.5.9.1.a. 

As aforementioned, this circuit must not be directed by microcontroller or software, by anything aside from hard-wired, analog electronics. According to EV.5.9.1.b, the circuit must be directly controlled by the present Tractive System voltage.

There are a few reasons why stacking the LED's might be a better option, as made allowable by this rule. Not only does doing so allow for more uniform light distribution as well as higher light intensity from a single point source, but it also means that you can have multiple different types of LED's that are fixtured to the same housing to achieve different lighting conditions.

Shown to the left is our 2023 iteration of the TSAL Mount, equipped with stacked LED's.

As soon as the Tractive Voltage reaches the High Voltage (HV) threshold of 60V DC or 25VRMS defined by T.9.1.1, EV.5.9.3.b requires that the light flash at a frequency between 2 and 5 Hz in order to enhance its visibility by leveraging human visual sensitivity to convey information effectively. The human eye is particularly sensitive to changes in light, especially in peripheral vision. A blinking LED in this frequency range can easily attract attention, and the regulation to color this LED red in EV.5.9.3.b is likely because an untrained spectator would be deterred from approaching that particular color given that flashing red is commonly understood as a signal to indicate caution and potential danger.