Invention Application
- Patent Title: ELECTRIC MOTOR PROTECTION USING A VIRTUAL SPEED SWITCH
- Patent Title (中): 使用虚拟速度开关进行电机保护
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Application No.: US14710796Application Date: 2015-05-13
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Publication No.: US20160334468A1Publication Date: 2016-11-17
- Inventor: Subhash C. Patel , George E. Alexander
- Applicant: Schweitzer Engineering Laboratories, Inc.
- Main IPC: G01R31/34
- IPC: G01R31/34

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.
Public/Granted literature
- US09939492B2 Electric motor protection using a virtual speed switch Public/Granted day:2018-04-10
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