Electronic Trip Device Connection Monitoring via Test Current Superposition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronic trip devices in circuit breakers face challenges in ensuring both high availability and security, particularly in maintaining integrity and safety during faults, as they often fail to control their own integrity and safety effectively.
Innovation Solution
The electronic trip device incorporates test means with a current source to superimpose a test current on the primary current sensor, pre-processing means for filtering and amplifying signals, and fault control mechanisms to detect abnormalities such as temperature, circuit operation, and voltage issues, while maintaining the ability to control the actuator based on primary current values without disconnecting the sensor or altering its functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If test means are added to monitor current sensor connections, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the test current source with the existing signal processing circuitry of the electronic trip device. The test means are integrated into the same housing and share common components such as the microprocessor, memory, and communication interfaces, thereby adding monitoring functionality without proportionally increasing overall device complexity
Solution Approach 2:
The electronic processing assembly performs multiple functions: it processes primary current signals for trip decisions, generates test currents for connection monitoring, stores trip information in memory, and communicates status externally. This multi-functionality allows a single device to provide both protection and self-diagnosis capabilities
2Reliability
If test current is superimposed on primary current signal, then connection monitoring is enabled, but signal processing complexity increases
Solution Approach 1:
The system performs offset correction before trip decision processing. By pre-subtracting the known test current component from the sensor signal, the processing circuitry is simplified and can focus on detecting actual overcurrent conditions without needing to distinguish the test signal component during normal operation
Solution Approach 2:
The system continuously monitors the sensor output signal and uses feedback processing to distinguish between test current contributions and actual primary current. The microprocessor analyzes the signal characteristics and provides feedback control to maintain accurate trip decisions despite the superimposed test signal
3Reliability
If fault detection means are added, then security is improved, but device complexity increases
Solution Approach 1:
The fault detection functionality is merged with the existing microprocessor-based control system. The same processor that manages trip decisions also executes fault detection algorithms, monitors temperature sensors, and manages communication, thereby avoiding the need for separate dedicated fault detection hardware
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 solution enhances the trip device's ability to maintain high availability and security by continuously monitoring and controlling its state, preventing untimely triggering and ensuring reliable operation even in fault conditions, thus ensuring the circuit breaker's ability to detect overcurrents and open the main conductor effectively.
Implementation Method 1
at least one current sensor (4) to provide a signal representative of the intensity of a primary current (Is) in a main conductor (2)
Implementation Method 2
test means (31) having a current source (44) for circulating a first test current (I0) through the current sensor (4), said current source being connected to said current sensor via a current-limiting resistor (45) such that, without disconnecting said current sensor, the first test current is superimposed on the signal representing the intensity of the primary current (Is)
Implementation Method 3
pre-processing means (21) equipped with filtering means (22)
Implementation Method 4
the pre-processing means (21) further comprise an amplifier (23)
Implementation Method 5
a digital converter (24)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The device has a current sensor (4) to supply a signal representative of a current intensity in a main conductor. An actuator (6) actuates an opening mechanism of contacts in series with the conductor. An electronic processing unit (5) controls the actuator based on the signal values. The unit has a monitoring unit to monitor the state of connections of the sensor and/or actuator, and a display unit (32) to display an operating state of the device. The monitoring unit acts on the display unit to display the connection state, while maintaining processing to control the actuator. An independent claim is also included for a method for monitoring the state of connections of an electronic trip device.