Motor Minimum Starting Voltage: Technical Requirements
When starting a motor, maintaining the minimum starting voltage is crucial to ensure the motor reaches its required torque. The technical requirements for minimum motor starting voltage are explained below:
Minimum Motor Starting Voltage:
During motor starting, the terminal voltage should be maintained at approximately a level that allows the motor to achieve 100% of the required torque (Tr). The required torque is calculated using the following formula:
Tr = (% of full Voltage)^2 x Starting torque (greater than or equal to 100%)
Example 1:
Motor with 150% starting torque at full voltage with a constant torque load applied. Can we apply 80% starting voltage?
Solution: Tr = (0.8)^2 x 150 = 96 (approximately equal to 100%). Therefore, it is recommended to use a minimum of 82% of the rated voltage to run the motor because (0.82)^2 x 150 = 100.
Example 2:
Motor with 200% starting torque at full voltage with a constant torque load applied. Can we apply 80% starting voltage?
Solution: Tr = (0.8)^2 x 200 = 128 (greater than 100%). Therefore, it is recommended to use a minimum of 71% of the rated voltage to run the motor because Tr = (0.71)^2 x 200 = 100.
Example 3:
Motor with 250% starting torque at full voltage with a constant torque load applied. Can we apply 80% starting voltage?
Solution: Tr = (0.8)^2 x 250 = 160 (greater than 100%). Therefore, it is recommended to use a minimum of 64% of the rated voltage to run the motor because Tr = (0.64)^2 x 250 = 100.
Understanding the relationship between starting voltage and starting torque is essential for ensuring optimal motor performance. By adhering to the recommended minimum voltage levels for specific starting torque values, you can ensure reliable motor operation.
