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Tech Tip: Working with Electric Motors

Electric drive vehicles have high voltage electrical systems not found on typical vehicles powered only by gasoline or diesel engines. Because of this, it’s important to be aware of high voltage hazards before you inspect an electric motor. Specifically, be aware of the high voltage interlock switch.

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High Voltage Interlock Switch

Most BorgWarner electric motor models are outfitted with a standard safety feature—the high voltage interlock switch. Similar to the lockout tagout safety procedure, this interlock switch disables and deenergizes a high voltage system. It prevents high voltage from being present whenever vehicle inspection or maintenance needs to occur.

The BorgWarner interlock switch is integrated into the high voltage connection box. It is activated by the position of the box cover. When the cover is installed, it prevents access to the high voltage terminals. In this position, the interlock switch provides pin-to-pin continuity in the low voltage connector.

When the cover is removed, the interlock switch signals the inverter—which serves as the control system—to disable electricity currents into the motor. After the cover is off, remember that some high voltage components may continue to be energized for up to 10 minutes, so always use caution before touching the cables.

When you are done working, replace the cover back on the box. You’ll know whether or not it is on correctly by the inverter’s response. If the cover is put on backwards, the inverter will think it’s still off and, as a result, it won’t reactivate the current flow between the electrical components and the motor. This response serves as a fail-safe, ultimately protecting you until the cover is repositioned correctly.

Finally, it’s important to note that the interlock switch itself does not turn off any high voltage source. It simply provides a fail-safe signal to be used by the inverter.

Our latest tech tip video explains the high voltage interlock switch and its role in protecting you from serious injury caused by high voltage electricity. Watch it on the BorgWarner YouTube channel.

 

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