A method for preventing motor misoperation during engine overhaul
A motor and motive technology, applied in electrical components, emergency protection circuit devices, etc., can solve problems such as malfunction, inability to distinguish voltage drop, etc., to ensure the effect of normal operation
Active Publication Date: 2015-09-30
NANJING INTELLIGENT APP
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Problems solved by technology
The low-voltage protection of high-voltage motors generally judges that the three line voltages are lower than the fixed value at the same time and sends a trip command after a delay. The defect is that the protection cannot distinguish the cause of the voltage drop. Turn on the high-voltage motor, when the voltage transformer fails, it will also trip the outlet to trip the high-voltage motor, which is the so-called malfunction
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[0008] The technical solutions of the present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.
[0009] The low-voltage protection of the high-voltage motor in this embodiment is characterized in that the low-voltage protection adds a PT disconnection blocking logic: when the voltage of any phase line in the three line voltages is lower than 42V, and the other two line voltages are greater than 42V at the same time, Block low-voltage protection; if the three line voltages are lower than 10V at the same time, the protection current is greater than 0.1Ie (Ie is the rated current of the motor) and less than 1.2 Ie, and the low-voltage protection is blocked. When the PT is overhauled, although the line voltage meets the operating conditions, the protection current meets the blocking conditions at the same time, and the PT disconnection locks the low-voltage protection, which can ensure that the low-voltage protect...
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The invention provides a method for preventing false operation of a motor in PT (potential transformer) maintenance. The method includes low-voltage protection for the high-voltage motor, and is characterized in that PT disconnection lockout logic is additionally set for the low-voltage protection, the low-voltage protection is locked out when any one of three line voltages is lower than 42V and the other two line voltages are higher than 42V, and the low-voltage protection is locked out if the three line voltages are simultaneously lower than 10V and protection current is higher than 0.1Ie (the Ie refers to the rated current of the motor) and lower than 1.2Ie. Therefore, when the voltage of a power supply bus is normal, the potential transformer fails or PT maintenance is performed, the low-voltage protection does not function, false operation is prevented by the low-voltage protection, and accordingly, normal operation of the high-voltage motor is ensured.
Description
technical field [0001] The invention provides a method for preventing low-voltage misoperation of a motor during PT maintenance, and belongs to the technical field of relay protection and control in electric power systems. Background technique [0002] When the voltage of the power supply bus of the high-voltage motor drops for a short time or is interrupted and resumed, in order to prevent the serious drop of the power supply voltage when the motor starts automatically, a low-voltage protection is usually configured on the large motor. When the voltage of the power supply bus drops to a certain value, the large motor or the secondary motor will be cut off after a delay, so that the power supply bus has enough voltage to ensure the self-starting of the more important motors. The low-voltage protection of high-voltage motors generally judges that the three line voltages are lower than the fixed value at the same time and sends a trip command after a delay. The defect is that ...
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IPC IPC(8): H02H7/08
Inventor 张杭王大平周德顺李勇
Owner NANJING INTELLIGENT APP