Which of the following voltages are not safe for a 208-V motor to operate?

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Multiple Choice

Which of the following voltages are not safe for a 208-V motor to operate?

When a motor is rated for a specific voltage, it’s designed to operate safely within a small tolerance around that value. For a 208-V motor, a common tolerance is roughly ±10%, so the safe range is about 187 to 229 volts. Voltages inside this band let the motor run with normal current, torque, and heat. 208 volts is exactly at the rating, and 200 volts is within the safe window, so they are fine. A voltage like 238 volts is outside that safe range, which means the motor would experience higher magnetizing current, increased current draw, more heating, and potential insulation stress. That’s why 238 volts isn’t safe. 260 volts is even farther above the rating and would be even more unsafe.

When a motor is rated for a specific voltage, it’s designed to operate safely within a small tolerance around that value. For a 208-V motor, a common tolerance is roughly ±10%, so the safe range is about 187 to 229 volts. Voltages inside this band let the motor run with normal current, torque, and heat.

208 volts is exactly at the rating, and 200 volts is within the safe window, so they are fine. A voltage like 238 volts is outside that safe range, which means the motor would experience higher magnetizing current, increased current draw, more heating, and potential insulation stress. That’s why 238 volts isn’t safe. 260 volts is even farther above the rating and would be even more unsafe.

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