Cable Connection Testing via Frequency Converter Voltage Limiting
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Solution Overview
Problem
Existing methods for testing cable connections in shore-based electrical connections for ships are inadequate as they often cause insulation damage and pose safety risks due to high test voltages and currents, especially in harsh weather conditions, necessitating frequent and safe inspections.
Innovation Solution
A method utilizing a frequency converter to progressively increase voltage and limit short-circuit current to a threshold value, ensuring safety and minimizing stress on the cable connection by keeping the voltage 10% above nominal and current below rated levels, thereby allowing frequent and safe testing without risking people or equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high test voltage is applied to the cable connection to detect insulation faults, then measurement precision is improved, but object-affected harmful factors increase due to insulation damage and safety risks
Solution Approach 1:
The patent changes the voltage parameter from high test voltage (2.5 times nominal) to a limited voltage increase (maximum 10% above nominal voltage). This parameter change allows the test to proceed with much lower stress on the cable insulation, eliminating the harmful effects of high voltage while still enabling fault detection through current monitoring at the reduced voltage level.
2Reliability
If high test voltage is applied to ensure fault detection, then reliability is improved, but object-generated harmful factors increase due to ion bombardment and insulation damage
Solution Approach 1:
The patent reduces the voltage parameter from high levels that cause ionization and insulation damage to a safe level (10% above nominal maximum). At this reduced voltage, ion bombardment and insulation damage are eliminated while fault detection reliability is maintained through monitoring of current values that indicate insulation defects.
Solution Approach 2:
The patent introduces continuous monitoring of current values during the voltage increase process. When a current threshold is exceeded, the test is automatically stopped. This feedback mechanism ensures that even if insulation faults are present, they will not progress to dangerous levels, maintaining reliability while preventing harmful effects.
3Reliability
If frequent testing is performed to detect material defects early, then reliability is improved, but object-affected harmful factors increase due to cable stress from repeated high voltage application
Solution Approach 1:
The patent changes the voltage parameter from high test voltage to a limited voltage increase (maximum 10% above nominal). This allows the cable to be tested frequently without accumulating stress damage, as the reduced voltage levels do not harm the insulation even with repeated application.
4Measurement precision
If high test voltage is applied to locate insulation faults, then measurement precision is improved, but safety risks increase to people and equipment in the immediate vicinity
Solution Approach 1:
The patent reduces the voltage parameter from high levels (2.5 times nominal) to a safe level (10% above nominal maximum). This eliminates the safety risks to people and equipment while maintaining the ability to detect insulation faults through current monitoring at the reduced voltage level.
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 provides a safe and stress-reduced method for testing cable connections, allowing for repeated inspections without harm to individuals or equipment, while enhancing security by limiting voltage and current within safer thresholds.
Implementation Method 1
the current flow that occurs is recorded while obtaining measured current values and is monitored for the presence of a predetermined short-circuit criterion
Data Source
AI summary
In order to provide a method for testing a cable connection (12) extending between a distribution network (2) of a vessel (1) berthed in port and a frequency converter (6) of an electric power supply connection (3) located on land, wherein the voltage (U) that is applied to the cable connection (12) is increased progressively by means of the frequency converter (6) until a voltage threshold value is reached, the current flow that occurs is captured obtaining current measured values and monitored for the presences of a predetermined short-circuit criterion, which method can be repeated often and, in the event of a malfunction, the persons in the direct surroundings are not injured, it is proposed to predetermine a short-circuit current threshold value by means of the frequency converter (6), wherein the short-circuit criterion is fulfilled when the current measured values are equal to the short-circuit current threshold value.