Latching Magnet Test Device Using Short Pulses
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Solution Overview
Problem
Existing methods for testing latching magnets in power circuit breakers involve a permanent current flow, which is inefficient and does not effectively identify defects without tripping the magnet.
Innovation Solution
A method and test device that close the circuit for a short time to prevent contact separation, allowing for post-closure testing of energy dissipation in the latching magnet, utilizing a current sensor and comparator to detect voltage drops indicative of energy dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a steady-state test current is passed through the winding to test for wire breakage, then defects can be identified, but current flows permanently through the winding causing energy waste
Solution Approach 1:
The patent applies periodic action by using pulsed test currents instead of continuous steady-state current. The test device sends periodic test pulses through the winding during normal operation, allowing defect detection without continuous energy consumption. The pulsed nature of the test current enables the system to monitor winding integrity while minimizing power waste.
2Reliability
If a test current is passed through the winding to test for wire breakage, then defects can be identified, but the current may cause tripping of the latching magnet
Solution Approach 1:
The patent applies local quality by using different current characteristics for different testing purposes. The test device uses low-current pulses for winding integrity testing that are insufficient to actuate the latching magnet, while the system separately handles high-current tripping operations. This localized differentiation of current properties enables defect detection without causing unwanted tripping.
3Reliability
If continuous current monitoring is implemented to detect wire breakage, then defects can be identified in real-time, but the device complexity increases
Solution Approach 1:
The patent applies self-service by using the existing operational current path for testing purposes. The test device leverages the normal current flow through the latching magnet winding during switch operation to perform defect detection, eliminating the need for separate continuous monitoring circuits. The system essentially tests itself during regular operation, reducing overall device complexity.
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
This approach identifies defects in the latching magnet during normal operation without tripping, using a short test pulse to assess energy dissipation without continuous current flow, enhancing diagnostic efficiency.
Implementation Method 1
the plunger is attracted, counter to the force of a spring, by the magnetic field of the permanent magnet
Implementation Method 2
a latching magnet (Maglatch), which has a permanent magnet
Implementation Method 3
an opposing magnetic field being generated by the winding arranged on the permanent magnet, which opposing magnetic field compensates for the magnetic field of the permanent magnet
Implementation Method 4
a winding and a ferromagnetic plunger
Implementation Method 5
a current sensor and comparator to detect voltage drops indicative of energy dissipation
Data Source
AI summary
A method and a test device are disclosed for testing a latching magnet of a switch. The switch includes a switching contact; an electronic trip unit to monitor the current flowing and to test whether a current-dependent trip condition is met; an electrical energy store, forming a circuit with the winding of the latching magnet, the circuit being closed by the trip unit when the trip condition is met; an actuator, actuated for a first closing time by closing of the circuit and configured to separate the contact elements; and a first diode, connected in parallel with the winding and via which stored energy of the latching magnet is dissipated. The test device is configured to close the circuit for a second closing time, which is so short that no actuation of the actuator takes place. After the reopening, a test is performed to ascertain whether stored energy is dissipating.