Low-Current Run Plug Circuit for Spark-Safe Underwater Power
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Solution Overview
Problem
Traditional run plugs in battery-powered systems pose safety risks due to high current surges when inserted, potentially causing sparks and explosions in environments with flammable vapors, and are not designed for use in wet conditions or with small conductors.
Innovation Solution
A low-current run plug circuit featuring 1st and 2nd terminals, a run plug, and a safety circuit comprising a JFET, P-channel MOSFET, voltage divider, and N-channel MOSFET, which creates a low-impedance path when installed and isolates terminals when removed, reducing current flow to prevent sparks and allowing use with small conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional run plug is installed to power the system, then the system can be powered on and operated, but high current surges occur that can cause sparks and explosions in hazardous environments
Solution Approach 1:
The patent introduces an intermediary safety circuit between the battery and the load that mediates the power connection. This circuit includes current-limiting components and controlled switching elements that prevent direct high-current connection while still enabling safe power delivery when the run plug is installed.
Solution Approach 2:
The patent changes the electrical parameters of the connection by implementing controlled impedance and current limiting. The safety circuit transforms the direct low-impedance connection of traditional run plugs into a high-impedance, current-limited connection that prevents harmful current surges while maintaining operational functionality.
2Power
If a traditional run plug design is used where all battery power is present at the connector, then the system can be powered, but the available battery power creates safety hazards in wet and hazardous conditions
Solution Approach 1:
The safety circuit acts as an intermediary that controls and regulates power delivery. It includes between the battery and the run plug connector, ensuring that full battery power is not directly exposed at the connector while still enabling adequate power delivery to the load when needed.
Solution Approach 2:
The safety circuit performs preliminary action by pre-regulating and limiting the power available at the connector before the run plug is even installed. This prevents the hazardous condition of full battery power being present at the external connector in wet or explosive environments.
3Weight of moving object
If small conductors are used with traditional run plugs, then the device size can be reduced, but the high current capability requirements demand large conductors for safety
Solution Approach 1:
The patent changes the current parameter by implementing current limiting in the safety circuit. This allows the use of smaller conductors with higher current-carrying capacity ratings because the actual current flowing through them is limited to safe levels, providing an adequate safety margin even with reduced conductor size.
4Loss of energy
If the run plug is removed to turn off the system, then no power is consumed, but all battery power remains present at the connector creating ongoing safety risks
Solution Approach 1:
The safety circuit remains as an intermediary even when the run plug is removed. It includes components that ensure the connector terminals do not have full battery power present at them at any time, whether the plug is installed or removed, thereby eliminating the residual electrical hazard while maintaining the ability to power on/off functionality.
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 significantly reduces the risk of sparks and explosions by limiting current flow to a safe level (tens of microamps), enabling safe operation in hazardous environments and underwater conditions while allowing the use of small conductors.
Implementation Method 1
The JFET has a gate terminal (G1), a drain terminal (D1), and a source terminal (S1). The drain terminal D1 is configured to be electrically connected to a cathode of the apparatus' battery. The current set resistor (RA) is electrically connected between the 1st terminal and S1. The gate terminal G1 is electrically connected between the 1st terminal and RA such that a current IA flowing to the 1st terminal is set by a transfer function of the JFET and RA.
Implementation Method 2
The P-channel MOSFET has a gate terminal (G2), a drain terminal (D2), and a source terminal (S2). The drain terminal D2 is configured to be electrically connected to an electrical load within the battery-powered apparatus. The voltage divider has an input (Vin), an output (Vout), and a ground terminal (GR1). The Input Vin is electrically connected to S2 and D1, and the output Vout is electrically connected to G2.
Implementation Method 3
The N-channel MOSFET has a gate terminal (G3), a drain terminal (D3), and a source terminal (S3). The drain terminal D3 is electrically connected to GR1. The gate terminal G3 is electrically connected to the 2nd terminal, and S3 is electrically connected to a ground such that when the run plug is removed the N-channel MOSFET and the P-channel MOSFET are in cutoff wherein no current flows to the electrical load.
Data Source
AI summary
A low-current run plug circuit comprising: a run plug configured to electrically connect 1st and 2nd terminals when the run plug is installed; a safety circuit mounted within the battery-powered apparatus comprising: a JFET a current set resistor a P-channel MOSFET, a voltage divider, and an N-channel MOSFET connected together such that when the run plug is removed the N-channel MOSFET and the P-channel MOSFET are in cutoff wherein no current flows to the electrical load, and such that when the run plug is installed, the safety circuit creates a low-impedance electrical path from the cathode to the electrical load.