Invention Application
US20160334468A1 ELECTRIC MOTOR PROTECTION USING A VIRTUAL SPEED SWITCH 有权
使用虚拟速度开关进行电机保护

ELECTRIC MOTOR PROTECTION USING A VIRTUAL SPEED SWITCH
Abstract:
Detection of a locked rotor condition of an electric motor during startup herein uses a virtual speed switch. The methods and systems herein determine whether the motor is in a starting state, and the monitor the motor current to determine if it is greater than a predetermined threshold, and that the motor current decrease exceeds a predetermined threshold after a predetermined amount of time. If the decrease in motor current is not less than a predetermined threshold, then a speed switch bit is set, indicating that the rotor is turning. The methods and systems herein further determine whether a physical speed switch is faulty, and determine a locked rotor condition using the virtual speed switch signal, a physical speed switch signal, and whether the physical speed switch is faulty.
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