Motor Protector Power Sequencing for Fast Ground Fault Tripping
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Solution Overview
Problem
Existing motor protectors face challenges in implementing ground fault protection quickly and simultaneously considering automatic reclosing functions, especially when the rated current is small.
Innovation Solution
A power supply device for a motor protector is designed with three distinct power supplying units: one for the tripping device, one for the calculation and control device, and one for the reclosing device. The control unit prioritizes power distribution to ensure the tripping device receives power first, allowing for rapid ground fault protection, while also pre-storing power for automatic reclosing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power is supplied to all devices simultaneously, then all functions can operate, but ground fault protection response time increases
Solution Approach 1:
The control unit pre-configures power distribution priorities before faults occur. The first power supplying unit is designated to receive power first for the tripping device to enable rapid ground fault protection, while the third power supplying unit for the reclosing device receives power last, establishing a predetermined power allocation hierarchy that ensures fast protection response without requiring complex real-time decision-making
2Speed
If power is prioritized to tripping device, then ground fault protection is faster, but reclosing function cannot be performed
Solution Approach 1:
The power supply system is segmented into three independent power supplying units, each dedicated to a specific function: the first power supplying unit for the tripping device, the second power supplying unit for the calculation and control device, and the third power supplying unit for the reclosing device. This segmentation allows each unit to operate independently with its own power allocation, enabling the tripping device to receive power first for fast ground fault protection while the reclosing device maintains its own power supply capability for subsequent automatic reclosing operations
Solution Approach 2:
The control unit pre-configures power distribution priorities before faults occur. The first power supplying unit is designated to receive power first for the tripping device to enable rapid ground fault protection, while the third power supplying unit for the reclosing device receives power last, establishing a predetermined power allocation hierarchy that ensures fast protection response without compromising reclosing capability
3Reliability
If auxiliary power supply is used, then protection function is reliable, but extra wiring and installation complexity increase
Solution Approach 1:
The motor protector utilizes the motor's own power supply line as the energy source through the power supplying coil, eliminating the need for external auxiliary power supplies and additional wiring. The system converts the motor's operating current into usable power for its protection and control functions, making the device self-sufficient and simplifying installation while maintaining reliable operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the ground fault protection function to be initiated and completed more quickly, even at small rated currents, while also considering the automatic reclosing function, thus enhancing the overall protection and efficiency of the motor protector.
Implementation Method 1
the motor protector receives power by inducing alternating current in a power supply line of a motor via a power supplying coil and converting the induced alternating current into direct current utilizing a rectifier device
Data Source
AI summary
The disclosure relates to a power supply device for a motor protector and a power supplying method thereof. The motor protector receives power. The power supply device comprises: a first power supplying unit, configured to receive and store the power and supply power to a tripping device of the motor protector; a second power supplying unit, configured to receive the power and supply power to a calculation and control device of the motor protector; a third power supplying unit, configured to receive and store the power and supply power to a reclosing device of the motor protector; and a control unit, configured to control an order in which the first power supplying unit, the second power supplying unit and the third power supplying unit receive the power.