Electromagnetic Operation Device Temperature Compensation Circuit

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Solution Overview

Problem

Existing electromagnetic operation devices for switching devices like circuit breakers face issues with maintaining optimal excitation current of the electromagnet coil across varying ambient temperatures, leading to potential operation failures when temperature sensors fail, resulting in excessive mechanical loads and reduced service life.

Innovation Solution

The solution involves a control circuit with switching relays and limiting resistors that automatically adjust the excitation current of the electromagnet coil based on ambient temperature, ensuring normal operation even if the temperature sensor fails by short-circuiting the limiting resistor to maximize the excitation current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If resistors are switched according to ambient temperature to control electromagnetic force, then the electromagnetic force is maintained within a specified range, but the system complexity increases and reliability decreases when sensors fail

Engineering Contradiction:
Improveelectromagnetic forceVSAvoidoperation reliability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by providing a bypass path with a second resistor that activates when the temperature sensor or switching element fails. This bypass path ensures that even if the primary temperature-controlled resistance switching fails, the system still maintains functional operation through the alternative path, preventing complete system failure and cushioning against the adverse effects of sensor failure.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent uses an intermediary approach by introducing a switching element that can selectively connect between different resistance paths. The switching element acts as a mediator that normally routes current through temperature-dependent resistors but can also activate an alternative path when failure is detected, thereby maintaining system functionality through intermediate control states.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Speed

If the excitation current of the electromagnet coil is increased to maintain turn-on speed when residual magnetic flux is reduced, then the turn-on speed is maintained, but the mechanical loads to components are increased

Engineering Contradiction:
Improveturn-on speedVSAvoidmechanical load on components
Core Design Contradiction:
SpeedVSStrength

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the excitation current parameters based on ambient temperature. Through the resistor switching mechanism, the system changes the electrical parameters (current magnitude) to compensate for temperature-induced changes in magnetic properties, thereby maintaining constant turn-on speed across different temperatures without subjecting components to excessive mechanical loads.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If the electrostatic capacity of the capacitor is increased in response to temperature increase, then the energy accumulation is increased, but the excitation current of the electromagnet coil is increased excessively

Engineering Contradiction:
Improveenergy accumulationVSAvoidexcitation current
Core Design Contradiction:
Use of energy by moving objectVSForce

Solution Approach 1:

The patent applies local quality by introducing localized resistance elements (first and second resistors) at specific points in the circuit to locally control and limit the excitation current. While the capacitor's energy accumulation increases with temperature, the locally placed resistors ensure that the current delivered to the electromagnet coil remains within appropriate limits, preventing excessive force generation.

Inventive Principle:
Principle #3Local quality

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 ensures reliable turn-on operations across varying temperatures and reduces mechanical loads, preventing operation failures and extending the service life of the equipment.

Implementation Method 1

an electromagnetic operation device that employs an electromagnet

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a capacitor accumulating energy for exciting the electromagnet coil

Methodology Applied
Scientific EffectElectrostatic capacity: Capacitance

Data Source

PatentEP3370244B1Electromagnetic operation device and electromagnetic operation-type switching apparatus
Publication Date: 2019.07.10 HITACHI IND EQUIP SYST CO LTD
  • EP3370244B1 patent drawingFigure 1
  • EP3370244B1 patent drawingFigure 2
  • EP3370244B1 patent drawingFigure 3

AI summary

Excitation current of an electromagnet coil is changed in response to a change in ambient temperature and, even if a sensor that measures the ambient temperature fails, turn-on operation can be normally realized (completed). An electromagnetic operation device of the present invention includes an electromagnet coil for forming an electromagnet; a capacitor accumulating energy for exciting the electromagnet coil; and a control circuit for causing the electromagnet coil and the capacitor to be electrically connected according to a turn-on command or a turn-off command to a switching device; wherein the control circuit includes a limiting resistor at the time of turn-on operation, and a short-circuiting mechanism that is provided in parallel with the limiting resistor at the time of turn-on operation and short-circuits the limiting resistor at the time of turn-on operation by using a normally-closed contact point that is normally "closed" and is "opened" when a signal is inputted.