GB2554424A - Safety trip device - Google Patents
Safety trip device Download PDFInfo
- Publication number
- GB2554424A GB2554424A GB1616353.7A GB201616353A GB2554424A GB 2554424 A GB2554424 A GB 2554424A GB 201616353 A GB201616353 A GB 201616353A GB 2554424 A GB2554424 A GB 2554424A
- Authority
- GB
- United Kingdom
- Prior art keywords
- circuit
- voltage
- protection
- protection circuit
- vref
- Prior art date
- Legal status (The legal status 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 status listed.)
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/04—Arrangements for preventing response to transient abnormal conditions, e.g. to lightning or to short duration over voltage or oscillations; Damping the influence of dc component by short circuits in ac networks
- H02H1/043—Arrangements for preventing response to transient abnormal conditions, e.g. to lightning or to short duration over voltage or oscillations; Damping the influence of dc component by short circuits in ac networks to inrush currents
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
Abstract
A safety trip device for protection of a load in a low voltage circuit has a protection circuit comprising a MOSFET transistor Q1, a latch off control 2, a resistor R1, and a voltage reference Vref. These components are arranged such that during normal operation the voltage drop across MOSFET Q1 is replicated across resistor R1 and compared with voltage reference Vref such that when the voltage across R1 is less than Vref, Q1 conducts and when the voltage across R1 is greater than Vref, Q1 is latched off. The device may further comprises a start-up protection circuit that allows an initial overcurrent for a limited time period when the protection circuit is started up. This may be achieved by additionally providing the protection circuit with a capacitor C1, resistors R2 and R3, and a MOSFET transistor Q2 and suitably arranging them within the protection circuit.
Description
(71) Applicant(s):
Pulse Lighting Limited
39a Highmeres Road, Thurmaston, Leicester, LE4 9LZ, United Kingdom (56) Documents Cited:
JP 2009142146 A US 7203046 B2 US 5465188 A
JP 2004226185 A US 5926354 A US 4937697 A (72) Inventor(s):
Paul Acton Gareth Knight (58) Field of Search: INT CL H02H
Other: Online: WPI, EPODOC (74) Agent and/or Address for Service:
Serjeants LLP
Dock, 75 Exploration Drive, Leicester, LE4 5NU, United Kingdom (54) Title of the Invention: Safety trip device Abstract Title: Safety trip device (57) A safety trip device for protection of a load in a low voltage circuit has a protection circuit comprising a MOSFET transistor Q1, a latch off control 2, a resistor R1, and a voltage reference Vref. These components are arranged such that during normal operation the voltage drop across MOSFET Q1 is replicated across resistor R1 and compared with voltage reference Vref such that when the voltage across R1 is less than Vref, Q1 conducts and when the voltage across R1 is greater than Vref, Q1 is latched off. The device may further comprises a start-up protection circuit that allows an initial overcurrent for a limited time period when the protection circuit is started up. This may be achieved by additionally providing the protection circuit with a capacitor C1, resistors R2 and R3, and a MOSFET transistor Q2 and suitably arranging them within the protection circuit.
Figure 1
VCC
co
2/3
Figure 2
Figure 3
- 1 TITLE
Safety Trip Device
DESCRIPTION
Field of Invention
The present invention relates to the protection of apparatus used in distributed circuits, such as LED lighting. The invention provides a device containing a simple circuit that is capable of protecting a single or multiple apparatus in a distributed circuit in the event of a fault with that apparatus whilst allowing the remaining apparatus in the distribution circuit to continue to function.
Background of the Invention
Distributed circuits are used for many purposes including the provision of LED lighting displays. A good example of such a circuit is a retail LED lighting display. A typical distributed circuit for a retail lighting display comprise a relatively high number of separate low power, low voltage apparatus that are connected together to a single electrical supply. It is generally necessary for such a circuit to include protection means that turn off any apparatus in the circuit should a fault develop with that apparatus. Preferably, the protection means should be capable of turning off an individual apparatus without it being necessary to turn off all other apparatus in the circuit. For example, it is much better if a single LED lighting apparatus of lighting display can be turned off in the event of a fault without the need to turn off each other LED lighting apparatus. This has the benefit of immediately locating the apparatus with which there is a fault. It also allows the rest of the lighting display to continue operating until the faulty apparatus is repaired or replaced.
Unfortunately, the protection means of many distributed circuits do not act in this manner. Rather, they simple turn off the entire circuit in the event of a fault with a single apparatus in the circuit. For example, a simple fuse may be provided in a power supply for a distributed circuit. This is disadvantageous in that it makes it difficult to isolate the apparatus with which there is a fault and it prevents the entire circuit from being operated until the fault is repaired or the faulty apparatus is replaced.
-2 Fuses are also disadvantageous in that they are required to be rated for the entire distribution circuit whereas different apparatus that form part of the circuit may have different effective ratings and require different protection. Some larger apparatus may include integrated protection means but smaller apparatus, such as LED lights, are unlikely to include integrated protection.
As an example, a distributed circuit may be generally rated to operate at 3 Amps. In such circumstances it is common to provide the distributed circuit with a protective fuse that is rated at double the rated current of the circuit. In this example a 6 Amp fuse may be provided. This will provide protection to all apparatus forming part of the circuit should the current exceed 6 Amps. However, a common problem is the distributed circuit being overloaded, for example such that the operating current increases to 4 Amps. In this scenario over a period of hours the fuse may become extremely hot and can then cause risk of fire and/or destroy the fuse.
As a further example, a 150 Watt power supply may be used to provide a 12.5 Amp supply to retail lighting display consisting of a distributed circuit having a plurality of LED lighting apparatus. It is necessary for all cables of that circuit to be rated at 12.5
Amps to be able to withstand a potential current fault in the circuit. However, LED lights are generally low power apparatus and as such require smaller cables that are not rated for a 12.5 Amp current. If a short circuit or a fault occurs on such a cable when it is used in such a distributed circuit it can result in the cable overheating, potentially causing a fire. Therefore, there is a need for a protection device that allows such cables to be used in relatively high current distributed circuits in order to disconnect the cable and any apparatus attached thereto should a short circuit or other fault occur.
In light of the above, there is a need for an improved protection device for apparatus of distributed circuits. Preferably, any such device should be suitable for protecting individual apparatus within the circuit in the event of a fault whilst still allowing other apparatus within the circuit to operate normally. Preferably any such device should be
-3 simple and low cost but provide quick and effective protection in the event of a fault. Further, it is preferable that any such device should be able to activate even for low current faults and should be suitable for use with low power apparatus that may be used with a higher rated distribution circuit.
Summary of the Invention
The present invention provides a safety trip device for protection of a load in a low voltage circuit, the device having a protection circuit comprising:
a mosfet transistor Qi;
o a latch off control;
a resistor Ri; and a voltage reference Vref arranged such that during normal operation:
when the voltage across Ri is less than Vref Qi conducts, when the voltage across Ri is greater than the Vref Qi provides a gate output that latches off the latch off control.
The safety trip device of the present invention is a simple device having a protection circuit that comprises simple and readily available components. In particular, the device provides quick and responsive protection using only simple components. As will be readily understood the safety trip device and protection circuit of the present invention are suitable for protecting relatively low voltage and low current DC loads, such as LED lighting strips and other similar loads.
The protection circuit operates in the following manner. When the voltage across Ri is higher than Vref Qi will be turned on and provide a gate output to the latch off control. The gate output is proportional to an output current that passes through Ri. When the voltage across Ri is less than Vref Qi is turned off and will act as a conductor. In this situation the latch off control is not latched off and a load can be supplied with a current. In this manner one or more loads can be protected from high currents that may occur during operation of the load by the device of the present invention. A load may be an LED lighting apparatus or any other suitable apparatus.
-4A load can be attached to the device of the present invention such that current is provided to the load through the protection circuit under the control of the latch off control. When the latch off control latches off no current will be provided to the load.
When the latch off control is on then current is provided to the load.
As will be readily understood in order for the protection circuit of the device of the present invention to operate satisfactorily it is necessary that Ri is selected to have a suitable resistance and an appropriate voltage reference is selected. It is anticipated that the skilled person will be able to select appropriate components for any given embodiment of the present invention.
It is common in DC distributed circuits for an initial overcurrent to be applied to the circuit during start-up. This can result in the tripping of a protection device that protects against all overcurrents, regardless of when they occur. This is known as nuisance tripping. Therefore, it is preferable that the protection circuit of the device of the present invention further comprises start-up protection that allows an initial overcurrent for a limited time period when the protection circuit is started up. This may be achieved in any manner apparent to a person skilled in the art. Allowing an initial overcurrent for a limited time period avoids the possibility of nuisance tripping.
It may be preferable that the start-up protection is formed of further simple electronic components in the protection circuit. For example, it may be preferable that the startup protection comprises:
a capacitor Ci;
resistors R2 and R3; and a mosfet transistor Q2; wherein
Ci and R2 are connected in a first series connection across inputs to the circuit such that on start-up Ci charges up through R2;
the drain-source connections of Q2 and R3 are connected in a second series connection across inputs to the circuit; and
- 5 the gate output of Q2 connects the second series connection to a point in the first series connection between Ci and R2; such that during start-up Ci is charged, Q2 is switched on and R3 is part of the circuit, start-up ending and normal operation beginning when Ci is fully charged thereby switching Q2 off and removing R3 from the circuit; wherein when part of the circuit, R3 is connected in parallel with Ri such that during start-up voltage across the parallel connection of Ri and R3 is measured across Qi.
That is, the start-up protection may comprise a capacitor, two resistors, and a mosfet transistor that are appropriately arranged in the protection circuit and have appropriate properties to allow an initial overcurrent during an initial start-up period but prevent overcurrents after the end of the initial start-up period. In order for this to happen capacitor Ci, resistors R2 and R3, and mosfet transistor Q2 of appropriate properties should be selected.
A protection circuit with start-up protection formed in this manner will operate as follows. At initial start-up capacitor Ci will be uncharged and an overcurrent will be applied to the protection circuit. During the initial start-up the capacitor Ci will charge through resistor R2 thereby allowing the overcurrent through the protection circuit.
During this initial start-up the trip point of the protection circuit is defined by resistors Ri and R3, which are connected in parallel such that voltage across the parallel connection of Ri and R3 is measured across Qi.
During this initial start-up period should the voltage across Qi exceed the reference voltage then the latch off control will be activated and the load will be protected. That is, when the voltage across the parallel connection of Ri and R3 exceeds the reference voltage then the latch off control is activated to latch off. This will protected the load from excessive currents that exceed the initially allowed overcurrent during initial start-up.
Once the capacitor Ci is fully charged the mosfet transistor Q2 is switched off and current no longer flows through R3. After Q2 is switched off the protection circuit will
-6function as normal in the manner set out above and protect the load from currents exceeding the standard operating current. In particular, after Q2 is switched off as a result of capacitor Ci becoming fully charged the voltage measured across Qi is equal to the voltage across Ri alone, instead of across the parallel connection of Ri and R3.
In preferred embodiments of the invention, the capacitor Ci will be selected such that it takes an appropriate amount of time to charge when the initial current is applied to the protection circuit. For example, Ci may be selected such that it takes between 0.1 and 1 second to charge when the initial current is applied to the device. In a preferred embodiment of the invention Ci may be selected such that it takes 0.5 seconds to charge. It is anticipated that it will be within the capacity of the skilled person to select a suitable capacitor based on the likely operating conditions of any embodiment of a device according to the present invention, those operating conditions including the expected initial overcurrent and standard operating current.
As set out above, the resistor R3 determines the overcurrent that is allowed in the protection circuit during initial start-up, whilst capacitor Ci charges. Thus, R3 should be selected to allow reasonable overcurrents, whilst also protecting the protection circuit and any load supplied by the device. It may be preferable, that R3 is selected to allow overcurrents of between 5 and 10 times the standard operating current during start-up. In an embodiment of the invention the overcurrents during start-up of the device may be expected to be approximately 8 times the standard operating current. It is anticipated that it will be within the capacity of the skilled person to select a suitable resistor for R3 based on the likely operating conditions of any embodiment of the device.
In order to provide a load supplied by the device with reverse polarity protection it may be preferable that device according to the present invention further comprises an output diode. An output diode may be provided in the protection circuit at an output of the latch off control such that current can flow from the latch off control to a load but cannot flow in the opposite direction.
-Ί A protection circuit of a device according to the present invention may either be provided as a circuit comprising separate connected components or may be provided as an integrated circuit having all of the necessary components.
A protection circuit may be able to be reset by switching the power supply to the circuit off and then restarting the power supply i.e. cycling the power supply.
A device according to the present invention may either be integrated with one or more loads or may be formed a separate plug-in unit to which one or more loads may be o attached. In a preferred embodiment of the invention the device may be formed as a T-junction connector, having an input to the distributed circuit at one side of the Tjunction, an output to a load at second side of the T-junction, and an output to the distributed circuit at a third side of the T-junction.
If a device according to the present invention is a modular unit it may be preferable that it is formed within a moulded plastic housing and has appropriate connections to allow it to be attached to a load within a distributed circuit.
Further details of the present invention will be apparent from a preferred embodiment that is shown in the Figures and is described below. In particular, embodiments of the present invention may comprise a protection circuit as illustrated in Figure 1.
Drawings
Figure 1 is a circuit diagram of a protection circuit of a device according to the present invention;
Figure 2 is a schematic of the use of devices according to the present invention in use in a distributed lighting circuit; and
Figure 3 is a flow diagram showing the generalised operation of embodiments of a device according to the present invention.
- 8 A protection circuit 1 of a trip unit 10 according to an embodiment present invention is shown in Figure 1. The trip unit 10 is intended to be used in a distributed lighting circuit 12 with a DC source 14.
The protection circuit 1 comprises a capacitor Ci, resistors Ri, R2, and R3, mosfet transistors Qi and Q2, an output diode Di, a voltage reference Vref, and a latch off control 2, and transient voltage suppression diodes TSVi and TSV2 arranged in the manner shown in Figure 1. The protection circuit 1 is used to protect a load (not shown) attached to the circuit. In particular, the protection circuit 1 allows an initial overcurrent to flow in the circuit during an initial period in which the capacitor Ci is charging and thereafter prevents an overcurrent flowing through the circuit to a load.
The protection circuit 1 operates in the following manner. During initial start-up the capacitor Ci is uncharged and is charged by current introduced into the protection circuit 1. The capacitor Ci is charged through resistor R2. During the period in which the capacitor Ci is charging the mosfet transistor Q2 is switched on and resistor R3 is connected in the protection circuit 1 such that the trip point of the protection circuit is defined by the parallel connection of resistors Ri and R3. This is because during this period the voltage across the parallel connection of Ri and R3 is measured across Qi. This allows overcurrents of approximately 8 times the normal operating current during this initial start-up period.
When the capacitor Ci is fully charged the mosfet transistor Q2 is switched off and the resistor R3 is removed from the circuit. After this point and during subsequent operation the point at which the protection circuit 1 trips (i.e. when the latch off control latches off) is determined by the resistance of resistor Ri. This is because during normal operation the voltage across resistor Ri alone is measured across Qi.
When the voltage across Qi exceeds the reference voltage Vref Qi provides a gate current output that is output to the latch off control 2 and latches off the latch off control. This means that during normal operation the latch off control 2 is latched off
-9when the voltage across Ri exceeds Vref. During initial start-up the latch off control 2 is latched off when the voltage across the parallel connection of Ri and R3 exceeds
Vref.
The protection circuit 1 can be reset by cycling the power supply to the protection circuit 1. That is, the protection circuit 1 can be reset by removing the power supply for a brief period of time in which the capacitor Ci will discharge and the protection circuit 1 will be reset to its initial state before power was supplied and can be used in the manner set out above. If a fault remains then the latch off control 2 will latch off again. If a fault that resulted in the latch off control 2 being activated was transient and no longer exists then the protection circuit 1 will allow power supply to the load again.
The operation of the protection circuit 1 to protect a load is achieved by selecting the components of the circuit to have suitable properties. For example, the capacitor Ci should be selected to have a capacitance that results in it charging for approximately 0.5 seconds on initial start-up of the protection circuit under typical conditions. Further resistors Ri, R3, and the voltage reference Vref should be selected to provide suitable overcurrent protection to the circuit during the initial start-up and during subsequent normal operation. The skilled person will be able to select suitable components for any particular embodiment of the present invention. For a typical LED lighting distributed circuit Vref may be approximately 4.7V.
A trip unit 10 according to the present invention may be integrated with a load 11, 12.
However, it is preferable that a trip unit 10 according to the present invention is a separate moulded unit 10 as shown schematically in Figure 2. The trip unit 10 of Figure 2 may allow connection to a single load 11 or to a plurality of loads 12. The trip unit 10 is designed to allow easy attachment to and removal from a distributed circuit and to allow a load to be easily attached and removed from a distributed circuit. A distributed lighting circuit 13 comprising one or more trip units 10 according to the present invention may be supplied by a suitable DC power source 14. Several trip units 10 may be connected together in a single distributed circuit. They
- 10may be either directly connected as shown in Figure 2 or may be connected via intermediate loom connectors (not shown) or any other intermediate part of a circuit.
The generalised operation of the embodiment of a trip unit 10 comprising the protection circuit 1 Figure 1 is shown in Figure 3. When a power supply 14 supplying the trip unit 10 is switched on to supply a DC current to a load 11, 12 the trip unit 10 will initially allow a high power to be transmitted to the load 11, 12 for a period of approximately 0.5s whilst the capacitor Ci charges. This prevents any initial inrush current from tripping the trip unit 10. After approximately 0.5s when the capacitor Ci is charged the power that is allowed to be transmit is within normal limits. If an overcurrent then occurs the trip unit 10 will latch off and will remain latched off until the power supply 14 is cycled. That is, after an overcurrent the trip unit 10 will latch off until the power supply 14 is turned off and then turned on again. When the power supply 14 is turned on again the trip unit 10 will operate as it did when the power unit
14 was initially switched on.
Claims (12)
1. A safety trip device for protection of a load in a low voltage circuit, the device having a protection circuit comprising:
a mosfet transistor Qi; a latch off control; a resistor Ri; and a voltage reference Vref arranged such that during normal operation:
a voltage across Ri is measured across Qi, when the voltage across Ri is less than Vref Qi conducts, when the voltage across Ri is greater than the Vref Qi provides a gate output that is compared to Vref at the latch off control such that the latch off control latches off when the voltage across Ri is greater than Vref.
2. A device according to claim 1, wherein the protection circuit further comprises start-up protection that allows an initial overcurrent for a limited time period when the circuit is started up.
3. A device according to claim 2, wherein the start-up protection comprises: a capacitor Ci;
resistors R2 and R3; and a mosfet transistor Q2; wherein
Ci and R2 are connected in a first series connection across inputs to the circuit such that on start-up Ci charges up through R2;
the drain-source connections of Q2 and R3 are connected in a second series connection across inputs to the circuit; and the gate output of Q2 connects the second series connection to a point in the first series connection between Ci and R2; such that during start-up Ci is charged, Q2 is switched on and R3 is part of the circuit, start-up ending and normal operation beginning when Ci is fully charged thereby switching Q2 off and removing R3 from the circuit; wherein
- 12when part of the circuit, R3 is connected in parallel with Ri such that during start-up voltage across the parallel connection of Ri and R3IS measured across Qi.
4. A device according to claim 3, wherein Ci is selected such that it takes between 0.1 and 1 second to charge when an initial overcurrent is input to the device.
5. A device according to claim 4, wherein Ci is selected such that it takes 0.5 seconds to charge.
6. A device according to any of claims 3 to 5, wherein R3 is selected to allow overcurrents of between 5 and 10 times the standard operating current during start-up.
7. A device according to any preceding claim further comprising an output diode to provide reverse polarity protection.
8. A device according to any preceding claim wherein the protection circuit further comprises one or more transient voltage suppression diodes.
9. A device according to any preceding claim formed as a plug-in modular unit.
10. A device according to claim 9, formed as a T-junction connector.
11. A device according to claim 9 or claim 10, formed within a moulded plastic housing.
12. A device according to any preceding claim wherein components of the protection circuit are arranged in the manner shown in Figure 1.
Intellectual
Property
Office
Application No: Claims searched:
GB1616353.7 Ito 12
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1616353.7A GB2554424B (en) | 2016-09-27 | 2016-09-27 | Safety trip device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1616353.7A GB2554424B (en) | 2016-09-27 | 2016-09-27 | Safety trip device |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB201616353D0 GB201616353D0 (en) | 2016-11-09 |
| GB2554424A true GB2554424A (en) | 2018-04-04 |
| GB2554424B GB2554424B (en) | 2020-04-08 |
Family
ID=57539958
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1616353.7A Active GB2554424B (en) | 2016-09-27 | 2016-09-27 | Safety trip device |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2554424B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108714488A (en) * | 2018-05-14 | 2018-10-30 | 商洛学院 | A kind of chemical experiment centrifuge |
| US10770884B2 (en) * | 2016-03-24 | 2020-09-08 | Autonetworks Technologies, Ltd. | Power supply control apparatus |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4937697A (en) * | 1989-05-22 | 1990-06-26 | Motorola, Inc. | Semiconductor device protection circuit |
| US5465188A (en) * | 1990-12-13 | 1995-11-07 | Raychem Limited | Circuit protection device |
| US5926354A (en) * | 1997-06-11 | 1999-07-20 | International Rectifier Corporation | Solid state relay and circuit breaker |
| JP2004226185A (en) * | 2003-01-22 | 2004-08-12 | Mitsumi Electric Co Ltd | Overcurrent detection circuit and its delay circuit |
| US7203046B2 (en) * | 2005-01-17 | 2007-04-10 | Yazaki Corporation | Overcurrent detecting device |
| JP2009142146A (en) * | 2007-11-16 | 2009-06-25 | Furukawa Electric Co Ltd:The | Power supply device and power supply feeding method |
-
2016
- 2016-09-27 GB GB1616353.7A patent/GB2554424B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4937697A (en) * | 1989-05-22 | 1990-06-26 | Motorola, Inc. | Semiconductor device protection circuit |
| US5465188A (en) * | 1990-12-13 | 1995-11-07 | Raychem Limited | Circuit protection device |
| US5926354A (en) * | 1997-06-11 | 1999-07-20 | International Rectifier Corporation | Solid state relay and circuit breaker |
| JP2004226185A (en) * | 2003-01-22 | 2004-08-12 | Mitsumi Electric Co Ltd | Overcurrent detection circuit and its delay circuit |
| US7203046B2 (en) * | 2005-01-17 | 2007-04-10 | Yazaki Corporation | Overcurrent detecting device |
| JP2009142146A (en) * | 2007-11-16 | 2009-06-25 | Furukawa Electric Co Ltd:The | Power supply device and power supply feeding method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10770884B2 (en) * | 2016-03-24 | 2020-09-08 | Autonetworks Technologies, Ltd. | Power supply control apparatus |
| CN108714488A (en) * | 2018-05-14 | 2018-10-30 | 商洛学院 | A kind of chemical experiment centrifuge |
Also Published As
| Publication number | Publication date |
|---|---|
| GB201616353D0 (en) | 2016-11-09 |
| GB2554424B (en) | 2020-04-08 |
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