WO2000064024A1 - Downhole electronics protection apparatus - Google Patents

Downhole electronics protection apparatus Download PDF

Info

Publication number
WO2000064024A1
WO2000064024A1 PCT/GB2000/001377 GB0001377W WO0064024A1 WO 2000064024 A1 WO2000064024 A1 WO 2000064024A1 GB 0001377 W GB0001377 W GB 0001377W WO 0064024 A1 WO0064024 A1 WO 0064024A1
Authority
WO
WIPO (PCT)
Prior art keywords
electronic circuit
downhole
supply line
downhole electronic
protection device
Prior art date
Application number
PCT/GB2000/001377
Other languages
French (fr)
Inventor
Iain Maciver Maclean
Original Assignee
Expro North Sea Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Expro North Sea Limited filed Critical Expro North Sea Limited
Priority to AU41287/00A priority Critical patent/AU4128700A/en
Publication of WO2000064024A1 publication Critical patent/WO2000064024A1/en

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/01—Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like
    • E21B47/017—Protecting measuring instruments
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • H02H9/026—Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient

Definitions

  • the present invention relates to electronic circuit protection networks and in particular, though not exclusively, to an electronic protection network for the protection of electronic circuitry permanently located inside oil and/or gas wells.
  • Downhole electronics apparatus which share resources are liable to complete failure in the event of a fault occurring in any one of the downhole electronic circuits. For example, where a common voltage line is connected, via branch lines, to a number of downhole electronic circuits, if any electronic circuit develops a short circuit fault, the supply line voltage will be pulled down to zero volts and an expensive downhole network would be rendered inoperable .
  • One solution to this problem is in adding a protection circuit on each branch line between the shared cable and each downhole circuit. If a downhole electronic circuit fails and short circuits, then the protection circuit limits the current drawn by the faulty circuit thus allowing sufficient line voltage for the remaining downhole electronic circuits to function correctly, while limiting further damage to the short circuited downhole electronics circuit.
  • the major drawback to this arrangement is that the protection circuit electronics must be so reliable that network failure is extremely unlikely to occur as a result of an electronic circuit fault causing failure of the associated protection circuit. Protection circuit failures are likely during downhole electronic circuit fault conditions as the protection circuits may have to endure high voltages, high power dissipation and high temperature continuously as is the case with transistor based current limiting circuits or resistors.
  • downhole electronics protection apparatus for protecting at least two downhole electronic circuit for downhole monitoring and/or control, the at least two downhole electronic circuit being located in an oil and/or gas well, the at least two downhole electronic circuit being coupled to a common supply line via at least two branch supply lines emanating from said common supply line wherein, at least two protection devices are disposed on the at least two branch supply lines between the common supply line and the at least two downhole electronic circuits, and the at least two protection devices each having a resistance which changes with the amount of current flowing through each of said at least two protection devices .
  • the at least two protection devices are thermistors.
  • the thermistors are Positive Temperature Coefficient (PTC) thermistors whose resistance increases with temperature, caused by the ambient temperature plus the self-heating due to the amount of current flowing through the thermister. More conveniently, the resistance increases logarithmically with current .
  • PTC Positive Temperature Coefficient
  • At least two branch supply lines are terminated by said at least two protection devices.
  • This arrangement provides for redundancy in the apparatus wherein the at least two protection devices and downhole electronic circuits are physically in the same location performing the same function, and the inclusion of the at least two protection devices means that failure in one of the at least two downhole electronic circuits prevents that branch supply line acting as a short circuit on the common supply line and/or network communications.
  • Each downhole electronic circuit may be a control circuit.
  • the control circuit may measure some instruments and/or control a tool or valve within the well.
  • the downhole electronic circuit may also be a communications transceiver to provide for data communication between the surface and the downhole electronic circuit.
  • a method of protecting a downhole electronic circuit located in an oil and/or gas well, when a fault occurs in the downhole electronic circuit comprising the steps of: disposing a first protection device on a first branch supply line from a common supply line in the well, disposing a second protection device on a second branch supply line from the common supply line in the well, coupling the first protection device to a first downhole electronic circuit, coupling the second protection device to a second downhole electronic circuit, and in the event of a fault developing in the first downhole electronic circuit, a resistance of the first protection device increasing in response to the increase in current, power dissipation and internal temperature and limiting the current to the first downhole electronic circuit to protect the first downhole electronic circuit.
  • the method may include the further step of reducing current to the supply line after the fault has occurred to allow the protection device to re-set in the event that the fault was temporary and/or intermittent.
  • a method of protecting a downhole electronic circuit located in an oil and/or gas well, so that the downhole electronic circuit continues to operate when a fault occurs in a second downhole electronics circuit sharing a common supply line comprising the steps of : disposing a first protection device on a first branch supply line from the common supply line in the well, disposing a second protection device on a second branch supply line from the common supply line in the well, coupling the first protection device to a first downhole electronic circuit, coupling the second protection device to a second downhole electronic circuit, and in the event of a fault developing in the first downhole electronic circuit, increasing the resistance of the first protection device in response to the increase in current to limit the current drawn by the faulty first downhole electronic circuit and providing sufficient current to the second downhole electronics circuit for the second downhole electronic circuit to continue operating .
  • the method may include the further step of reducing current to the common supply line after the fault has occurred to allow the first protection device to re-set in the event that
  • Fig. 1 is a block diagram of a downhole electronics protection apparatus in accordance with an embodiment of the present invention
  • Fig. 2 is a block diagram of a downhole electronics protection apparatus in accordance with a preferred embodiment of the present invention
  • Fig. 3 is a circuit diagram of a downhole electronic protection device arranged within a downhole electronics circuit in accordance with the preferred embodiment of the present invention.
  • Fig. 1 of the drawings depicts a downhole electronics protection apparatus generally indicated by reference numeral 10.
  • a power supply unit (PSU) 12 is located outside a well at an accessible point for ease of maintenance. This is on the surface or, if the well was a subsea well, it would be positioned on the seabed.
  • a common voltage supply- line 14 is run from the PSU 12 into the well .
  • branch supply lines 18a, 18b, 18c are connected at downhole nodes 16a, 16b, 16c.
  • Three branch supply lines are shown in Fig. 1 but there could be any number incorporated.
  • Each branch supply line is connected to a current limiting protection device 20a, 20b, 20c respectively and in some cases the protection device 20a, 20b is coupled to a downhole electronic circuit 22a, 22b.
  • the protection device 20c terminates the branch supply line 18c leaving a terminal 24 available for future downhole electronic circuits to be attached.
  • Fig. 2 of the drawings illustrates a downhole electronics protection apparatus, generally indicated by reference numeral 10, according to a preferred embodiment of the present invention.
  • a power supply unit (PSU) and combined controller 112 are mounted on the surface of a well.
  • a common voltage supply line 114 carries power and communication links to downhole tools 122a and 122b.
  • the common voltage supply line 114 has branch supply lines 118a and 118b connected at nodes 116a, 116b. Each branch supply line 118a, 118b is connected through a respective PTC (Positive Temperature Coefficient) thermistor 120a, 120b to a respective downhole pressure tool 122a, 122b.
  • the thermistors 120a, 120b are model number B59870-C160-A70 manufactured by Siemens.
  • the downhole pressure tool 122a, 122b includes a downhole electronic circuit, generally indicated by reference numeral 121, illustrated in Fig. 3.
  • Common supply line 114 from power supply unit 112 is interrupted at node 116 to form branch supply line 118, which is connected to thermistor 120.
  • the other side of thermistor 120 is connected to the input of circuit 121.
  • the output 123 of the circuit 121 forms the current return to the PSU 112.
  • Circuit 121 draws its power through thermistor 120.
  • the line voltage is regulated down to 5V by regulators 126 and 128.
  • the pressure transducer outputs are fed into microcontroller 124 (type 87C51) .
  • the pressure and temperature are measured and the digital valves transmitted serially by the microcontroller 124.
  • the data is capacitively coupled onto the supply line 118 through capacitor 130.
  • the digital information is read by a reciprocal capacitive coupling circuit, not shown.
  • the control circuit 121 draws the required current through the thermistor 120.
  • a fault occurs within the control circuit 121, for instance the 87C51 chip 124 ceases to operate, heat is dissipated in the chip 124 causing other components to fail, a short circuit develops in the circuit 121 pulling increased current through the thermistor 120.
  • Thermistor 120 raises its resistance logarithmically as the current flow being drawn through it increases and ultimately limits the current flow at a predetermined level. This level is chosen to limit further damage occurring to the control circuit while leaving sufficient current in the common supply line 118 to keep other electronic circuits in other branch supply lines 114 in operation.
  • the principal advantage of the present invention is that failure of one downhole electronic circuit, within a downhole system sharing resources, will not cause complete failure of the system because current to the faulty circuit is limited, leaving sufficient supply for other circuits to draw sufficient current to operate normally.
  • the use of a PTC thermistor as the protection device has advantages in that it is simple, with less fault possibilities, when compared with transistor based current limiting circuits; it dissipates low power when compared to current limiting resistors; it is fundamentally designed to cope with high continuous temperatures seen in oil wells and it is resettable, unlike thermal fuses, which means that a downhole circuit subject to intermittent faults can recover.
  • the power supply unit and communications control may be located within the well. Further electronic circuits may be added and some circuits may activate valves as opposed to tools .

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Geophysics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

A downhole electronic protection apparatus is described for protecting electronic circuitry permanently located inside oil and/or gas wells. In one embodiment a suitable protection device into every branch supply line from the common shared resource line connected to a downhole electronic circuit, the protection device having a resistance which changes with the amount of current flowing through the protection device. Other embodiments of the invention are described.

Description

DOWNHOLE ELECTRONICS PROTECTION APPARATUS
The present invention relates to electronic circuit protection networks and in particular, though not exclusively, to an electronic protection network for the protection of electronic circuitry permanently located inside oil and/or gas wells.
In hydrocarbon exploration and production, it is common to install permanent monitoring and/or control instrumentation downhole in a well. With an increase in the number of multi- zone and multi-lateral wells being developed together with multi-well subsea installations, downhole electronics apparatus consisting of multiple downhole electronic circuits for downhole monitoring and/or control all sharing a common downhole-to-surface power and/or communication cable are now being implemented. Instances of these systems are greatly- increasing in downhole permanent monitoring and smart well control applications.
Downhole electronics apparatus which share resources are liable to complete failure in the event of a fault occurring in any one of the downhole electronic circuits. For example, where a common voltage line is connected, via branch lines, to a number of downhole electronic circuits, if any electronic circuit develops a short circuit fault, the supply line voltage will be pulled down to zero volts and an expensive downhole network would be rendered inoperable .
One solution to this problem is in adding a protection circuit on each branch line between the shared cable and each downhole circuit. If a downhole electronic circuit fails and short circuits, then the protection circuit limits the current drawn by the faulty circuit thus allowing sufficient line voltage for the remaining downhole electronic circuits to function correctly, while limiting further damage to the short circuited downhole electronics circuit. However, the major drawback to this arrangement is that the protection circuit electronics must be so reliable that network failure is extremely unlikely to occur as a result of an electronic circuit fault causing failure of the associated protection circuit. Protection circuit failures are likely during downhole electronic circuit fault conditions as the protection circuits may have to endure high voltages, high power dissipation and high temperature continuously as is the case with transistor based current limiting circuits or resistors.
It is an object of the present invention to provide a downhole electronics protection system which obviates or mitigates at least one of the aforementioned advantages.
This is achieved by inserting a suitable protection device into every branch supply line from the common shared resource line connected to a downhole electronic circuit, the protection device having a resistance which changes with the amount of current flowing through it.
According to a first aspect of the present invention, there is provided downhole electronics protection apparatus for protecting at least two downhole electronic circuit for downhole monitoring and/or control, the at least two downhole electronic circuit being located in an oil and/or gas well, the at least two downhole electronic circuit being coupled to a common supply line via at least two branch supply lines emanating from said common supply line wherein, at least two protection devices are disposed on the at least two branch supply lines between the common supply line and the at least two downhole electronic circuits, and the at least two protection devices each having a resistance which changes with the amount of current flowing through each of said at least two protection devices . Preferably, the at least two protection devices are thermistors. Conveniently, the thermistors are Positive Temperature Coefficient (PTC) thermistors whose resistance increases with temperature, caused by the ambient temperature plus the self-heating due to the amount of current flowing through the thermister. More conveniently, the resistance increases logarithmically with current .
Preferably, at least two branch supply lines are terminated by said at least two protection devices.
This arrangement provides for redundancy in the apparatus wherein the at least two protection devices and downhole electronic circuits are physically in the same location performing the same function, and the inclusion of the at least two protection devices means that failure in one of the at least two downhole electronic circuits prevents that branch supply line acting as a short circuit on the common supply line and/or network communications.
Each downhole electronic circuit may be a control circuit. The control circuit may measure some instruments and/or control a tool or valve within the well. Additionally, the downhole electronic circuit may also be a communications transceiver to provide for data communication between the surface and the downhole electronic circuit.
According to a second aspect of the present invention, there is provided a method of protecting a downhole electronic circuit located in an oil and/or gas well, when a fault occurs in the downhole electronic circuit, said method comprising the steps of: disposing a first protection device on a first branch supply line from a common supply line in the well, disposing a second protection device on a second branch supply line from the common supply line in the well, coupling the first protection device to a first downhole electronic circuit, coupling the second protection device to a second downhole electronic circuit, and in the event of a fault developing in the first downhole electronic circuit, a resistance of the first protection device increasing in response to the increase in current, power dissipation and internal temperature and limiting the current to the first downhole electronic circuit to protect the first downhole electronic circuit.
The method may include the further step of reducing current to the supply line after the fault has occurred to allow the protection device to re-set in the event that the fault was temporary and/or intermittent.
According to a third aspect of the present invention, there is provided a method of protecting a downhole electronic circuit located in an oil and/or gas well, so that the downhole electronic circuit continues to operate when a fault occurs in a second downhole electronics circuit sharing a common supply line, said method comprising the steps of : disposing a first protection device on a first branch supply line from the common supply line in the well, disposing a second protection device on a second branch supply line from the common supply line in the well, coupling the first protection device to a first downhole electronic circuit, coupling the second protection device to a second downhole electronic circuit, and in the event of a fault developing in the first downhole electronic circuit, increasing the resistance of the first protection device in response to the increase in current to limit the current drawn by the faulty first downhole electronic circuit and providing sufficient current to the second downhole electronics circuit for the second downhole electronic circuit to continue operating . The method may include the further step of reducing current to the common supply line after the fault has occurred to allow the first protection device to re-set in the event that the fault was temporary or intermittent.
These and other aspects of the invention will become apparent from the following description when taken in combination with the accompanying drawings in which:
Fig. 1 is a block diagram of a downhole electronics protection apparatus in accordance with an embodiment of the present invention;
Fig. 2 is a block diagram of a downhole electronics protection apparatus in accordance with a preferred embodiment of the present invention, and Fig. 3 is a circuit diagram of a downhole electronic protection device arranged within a downhole electronics circuit in accordance with the preferred embodiment of the present invention.
Reference is first made to Fig. 1 of the drawings which depicts a downhole electronics protection apparatus generally indicated by reference numeral 10. A power supply unit (PSU) 12 is located outside a well at an accessible point for ease of maintenance. This is on the surface or, if the well was a subsea well, it would be positioned on the seabed. A common voltage supply- line 14 is run from the PSU 12 into the well . At various locations on the common voltage supply line, branch supply lines 18a, 18b, 18c are connected at downhole nodes 16a, 16b, 16c. Three branch supply lines are shown in Fig. 1 but there could be any number incorporated. Each branch supply line is connected to a current limiting protection device 20a, 20b, 20c respectively and in some cases the protection device 20a, 20b is coupled to a downhole electronic circuit 22a, 22b. Alternatively, the protection device 20c terminates the branch supply line 18c leaving a terminal 24 available for future downhole electronic circuits to be attached. Reference is now made to Fig. 2 of the drawings which illustrates a downhole electronics protection apparatus, generally indicated by reference numeral 10, according to a preferred embodiment of the present invention. A power supply unit (PSU) and combined controller 112 are mounted on the surface of a well. A common voltage supply line 114 carries power and communication links to downhole tools 122a and 122b. The common voltage supply line 114 has branch supply lines 118a and 118b connected at nodes 116a, 116b. Each branch supply line 118a, 118b is connected through a respective PTC (Positive Temperature Coefficient) thermistor 120a, 120b to a respective downhole pressure tool 122a, 122b. The thermistors 120a, 120b are model number B59870-C160-A70 manufactured by Siemens.
The downhole pressure tool 122a, 122b includes a downhole electronic circuit, generally indicated by reference numeral 121, illustrated in Fig. 3. Common supply line 114 from power supply unit 112 is interrupted at node 116 to form branch supply line 118, which is connected to thermistor 120. The other side of thermistor 120 is connected to the input of circuit 121. The output 123 of the circuit 121 forms the current return to the PSU 112. Circuit 121 draws its power through thermistor 120. The line voltage is regulated down to 5V by regulators 126 and 128. The pressure transducer outputs are fed into microcontroller 124 (type 87C51) . The pressure and temperature are measured and the digital valves transmitted serially by the microcontroller 124. The data is capacitively coupled onto the supply line 118 through capacitor 130. At the power supply 112 the digital information is read by a reciprocal capacitive coupling circuit, not shown.
In use, the control circuit 121 draws the required current through the thermistor 120. In the event that a fault occurs within the control circuit 121, for instance the 87C51 chip 124 ceases to operate, heat is dissipated in the chip 124 causing other components to fail, a short circuit develops in the circuit 121 pulling increased current through the thermistor 120. Thermistor 120 raises its resistance logarithmically as the current flow being drawn through it increases and ultimately limits the current flow at a predetermined level. This level is chosen to limit further damage occurring to the control circuit while leaving sufficient current in the common supply line 118 to keep other electronic circuits in other branch supply lines 114 in operation.
It will be appreciated that the principal advantage of the present invention is that failure of one downhole electronic circuit, within a downhole system sharing resources, will not cause complete failure of the system because current to the faulty circuit is limited, leaving sufficient supply for other circuits to draw sufficient current to operate normally. The use of a PTC thermistor as the protection device has advantages in that it is simple, with less fault possibilities, when compared with transistor based current limiting circuits; it dissipates low power when compared to current limiting resistors; it is fundamentally designed to cope with high continuous temperatures seen in oil wells and it is resettable, unlike thermal fuses, which means that a downhole circuit subject to intermittent faults can recover.
It will be appreciated that various modifications may be made to the network hereinbefore described without departing from the scope of the invention. The power supply unit and communications control may be located within the well. Further electronic circuits may be added and some circuits may activate valves as opposed to tools .

Claims

1. Downhole electronics protection apparatus for protecting at least two downhole electronic circuit for downhole monitoring and/or control, the at least two downhole electronic circuit being located in an oil and/or gas well, the at least two downhole electronic circuit being coupled to a common supply line via at least two branch supply lines emanating from said common supply line wherein, at least two protection devices are disposed on the at least two branch supply lines between the common supply line and the at least two downhole electronic circuits, and the at least two protection devices each having a resistance which changes with the amount of current flowing through each of said at least two protection devices .
2. Apparatus as claimed in claim 1 wherein the at least two protection devices are thermistors.
3. Apparatus as claimed in claim 2 wherein the thermistors are positive temperature coefficient (PTC) thermistors whose resistance increases with temperature, caused by the ambient temperature plus the self-heating due to the amount of current flowing through the thermister .
4. Apparatus as claimed in any preceding claim wherein at least two branch supply lines are terminated by said at least two protection devices.
5. Apparatus as claimed in any preceding claim wherein each downhole electronic circuit is a control circuit.
6. Apparatus as claimed in claim 5 wherein the control circuit measures instruments and/or control a tool or valve within the well .
7. Apparatus as claimed in any one of claims 1 to 4 wherein the downhole electronic circuit is a communications transceiver to provide for data communication between the surface and the downhole electronic circuit.
8. A method of protecting a downhole electronic circuit located in an oil and/or gas well, when a fault occurs in the downhole electronic circuit, said method comprising the steps of : disposing a first protection device on a first branch supply line from a common supply line in the well, disposing a second protection device on a second branch supply line from the common supply line in the well, coupling the first protection device to a first downhole electronic circuit, coupling the second protection device to a second downhole electronic circuit, and in the event of a fault developing in the first downhole electronic circuit, a resistance of the first protection device increasing in response to the increase in current, power dissipation and internal temperature and limiting the current to the first downhole electronic circuit to protect the first downhole electronic circuit.
9. A method as claimed in claim 8 wherein the method includes the further step of reducing current to the supply line after the fault has occurred to allow the protection device to re-set in the event that the fault was temporary and/or intermittent.
10. A method of protecting a downhole electronic circuit located in an oil and/or gas well, so that the downhole electronic circuit continues to operate when a fault occurs in a second downhole electronics circuit sharing a common supply line, said method comprising the steps of: disposing a first protection device on a first branch supply line from the common supply line in the well, disposing a second protection device on a second branch supply line from the common supply line in the well, coupling the first protection device to a first downhole electronic circuit, coupling the second protection device to a second downhole electronic circuit, and in the event of a fault developing in the first downhole electronic circuit, increasing the resistance of the first protection device in response to the increase in current to limit the current drawn by the faulty first downhole electronic circuit and providing sufficient current to the second downhole electronics circuit for the second downhole electronic circuit to continue operating.
11. A method as claimed in claim 10 wherein the method includes the further step of reducing current to the common supply line after the fault has occurred to allow the first protection device to re-set in the event that the fault was temporary or intermittent .
PCT/GB2000/001377 1999-04-16 2000-04-17 Downhole electronics protection apparatus WO2000064024A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU41287/00A AU4128700A (en) 1999-04-16 2000-04-17 Downhole electronics protection apparatus

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9908575.5A GB9908575D0 (en) 1999-04-16 1999-04-16 Downhole electronics protection apparatus
GB9908575.5 1999-04-16

Publications (1)

Publication Number Publication Date
WO2000064024A1 true WO2000064024A1 (en) 2000-10-26

Family

ID=10851550

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2000/001377 WO2000064024A1 (en) 1999-04-16 2000-04-17 Downhole electronics protection apparatus

Country Status (3)

Country Link
AU (1) AU4128700A (en)
GB (1) GB9908575D0 (en)
WO (1) WO2000064024A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002019495A2 (en) * 2000-08-31 2002-03-07 Baker Hughes Incorporated Filter-switched drive operating mode control
CN100420116C (en) * 2002-06-19 2008-09-17 泰科电子有限公司 Multiple load protection and control device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995006352A1 (en) * 1993-08-23 1995-03-02 Raychem Corporation Use of ptc devices in wiring harnesses
GB2323109A (en) * 1997-03-14 1998-09-16 Baker Hughes Inc Power management system for downhole control system in a well

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995006352A1 (en) * 1993-08-23 1995-03-02 Raychem Corporation Use of ptc devices in wiring harnesses
GB2323109A (en) * 1997-03-14 1998-09-16 Baker Hughes Inc Power management system for downhole control system in a well

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002019495A2 (en) * 2000-08-31 2002-03-07 Baker Hughes Incorporated Filter-switched drive operating mode control
WO2002019495A3 (en) * 2000-08-31 2002-08-08 Baker Hughes Inc Filter-switched drive operating mode control
US6700762B2 (en) 2000-08-31 2004-03-02 Baker Hughes Incorporated Filter-switched drive operating mode control
CN100420116C (en) * 2002-06-19 2008-09-17 泰科电子有限公司 Multiple load protection and control device

Also Published As

Publication number Publication date
AU4128700A (en) 2000-11-02
GB9908575D0 (en) 1999-06-09

Similar Documents

Publication Publication Date Title
US8049361B2 (en) RF adapter for field device with loop current bypass
US7104462B2 (en) Low noise solid-state thermostat with microprocessor controlled fault detection and reporting, and programmable set points
US5835534A (en) Intrinsically safe barrier and field bus system
US4954923A (en) Intrinsic safety module interface
US6937958B2 (en) Controller for monitoring temperature
US6111738A (en) Intrinsically safe circuits
US8149683B2 (en) Fail-safe inline power in a wired data telecommunications network
KR20000005045A (en) Process for testing and ensuring the availability of a networked system
CN106383569A (en) Universal server power supply protection mechanism
EP3189299B1 (en) Electronic detonator leakage current restriction
CN104615093A (en) Intrinsically safe voltage clamping device
CN104564764A (en) Server system
CN101755374B (en) Intrinsically safe communications circuit
WO2000064024A1 (en) Downhole electronics protection apparatus
US7158041B2 (en) Electrical protection device and method for a communication circuit
US6912678B1 (en) System for identifying valid connections between electrical system components and responding to invalid connections
US20030131293A1 (en) Enhanced spur cable circuit protection device and method for its implementation
EP1747437A1 (en) Thermal protection for a vlsi chip through reduced c4 usage
JP6702780B2 (en) Protection circuit self-diagnosis device and protection circuit diagnosis method
KR20100027254A (en) Communication system for a surge protector
CN206894659U (en) A kind of reverse power supply device
US8560137B2 (en) High-voltage step-charge control for use in network-powered applications
KR102552333B1 (en) Terminal board for monitoring power state and State monitoring system having the same
CN213903717U (en) Power chip fault representation structure
TW201838375A (en) Reset device and method of power over ethernet system

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY CA CH CN CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP