EP0054407A1 - Laststromschutzschaltung - Google Patents
Laststromschutzschaltung Download PDFInfo
- Publication number
- EP0054407A1 EP0054407A1 EP19810305812 EP81305812A EP0054407A1 EP 0054407 A1 EP0054407 A1 EP 0054407A1 EP 19810305812 EP19810305812 EP 19810305812 EP 81305812 A EP81305812 A EP 81305812A EP 0054407 A1 EP0054407 A1 EP 0054407A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- switch
- circuit
- transistor
- diode
- potential
- 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.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
- G08B29/18—Prevention or correction of operating errors
- G08B29/20—Calibration, including self-calibrating arrangements
- G08B29/22—Provisions facilitating manual calibration, e.g. input or output provisions for testing; Holding of intermittent values to permit measurement
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
- G08B29/12—Checking intermittently signalling or alarm systems
- G08B29/14—Checking intermittently signalling or alarm systems checking the detection circuits
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
- H01H47/002—Monitoring or fail-safe circuits
Definitions
- the present invention relates to devices to protect against failure of switches. Such devices may also be used for testing switches without disturbing the system controlled by the switch.
- a device tc ensure continuation of current supply to a load in the event of failure of a switch, the device comprising a circuit connected in parallel with the switch and comprising means to cause voltage drop thereby to produce a reduced potential in the circuit, and a diode arranged to prevent current flow in the circuit when the potential at the load side of the switch is higher than the reduced potential, and to allow current flow when said potential is reduced tc a value lower than the reduced potential by virtue of the switch opening.
- the device further comprises means to detect current flow in the circuit.
- the base of a transistor is connected to a point in the circuit between the voltage reducing means and the diode, the two other connections of the transistor forming part of an alarm circuit which conducts only when said transistor is biased on by current flow in said circuit caused by opening of the switch.
- the alarm circuit may include a light emitting diode to give visible warning of switch opening.
- a method of testing a normally closed switch which comprises the steps of: connecting in parallel to said switch a circuit which comprises in series means to cause voltage drop thereby to produce a reduced potential in the circuit, a diode to prevent current flow in the circuit when the potential at the load side of the switch is higher than the reduced potential, and a connection point to the base of a transistor located between said means to cause a voltage drop and said diode, the two other connections of the transistor forming part of an alarm circuit; opening the switch; and checking the alarm circuit output.
- a method of testing a normally open switch which comprises the steps of: connecting in parallel with a second normally open switch and the load, a circuit which comprises in series means to cause voltage drop thereby to produce a reduced potential in the circuit, a connection point to the base of a transistor,and a dummy load; connecting the other connections of the transistor into ar alarm circuit; closing the normally open first-mentioned switch; and checking the alarm circuit output.
- FIG. 1 a basic circuit comprising a switch S and a device embodying the invention connected in parallel therewith between points A and B.
- the switch S is closed and the load L draws current from A to B through this switch.
- the device comprises, connected in sequence, a control transistor T2, connection point C, a diode Dl, connection point D, and isolating diode D2.
- Transistor T2 and diode Dl cause such a voltage drop as to produce a reduced potential in the circuit whereby current is prevented from flowing through isolating diode D2.
- transistor Tl does not conduct.
- the device of course can still be controlled by means of light emitting diode LED2 and transistor T2, and therefore if it is necessary for the load to be - switched off, this can be easily accomplished.
- a similar device for protection of a similar switch connected in the return path from the load L can be provided by reversing the diodes and using negative equivalents of the transistors.
- connection point D can be connected to an auxiliary supply bus ASB, from which connections can be taken to a number of isolating diodes, D2(a) and D2 (b) for example, each of which isolating diodes protects a switch S(a), S(b) respectively.
- a single device may protect a number of switches, each controlling a load.
- Each load has two individual control outputs, one in its supply path, and one in its return path.
- the common part of the supply path and the common part of the return path are each provided with a separate protection device connected respectively to the auxiliary supply bus ASB and the auxiliary return bus ARB.
- the device can also be used to test whether or not the switches are working. In the case of a normally closed switch, the switch is opened and the alarm circuit will give an output when the current bypasses the switch to flow through the protection device.
Landscapes
- Engineering & Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Keying Circuit Devices (AREA)
- Testing Electric Properties And Detecting Electric Faults (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8039358A GB2089591B (en) | 1980-12-09 | 1980-12-09 | Switch protection device |
GB8039358 | 1980-12-09 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0054407A1 true EP0054407A1 (de) | 1982-06-23 |
EP0054407B1 EP0054407B1 (de) | 1985-10-23 |
Family
ID=10517844
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19810305812 Expired EP0054407B1 (de) | 1980-12-09 | 1981-12-09 | Laststromschutzschaltung |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0054407B1 (de) |
DE (1) | DE3172734D1 (de) |
GB (1) | GB2089591B (de) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2253065A1 (es) * | 2004-03-22 | 2006-05-16 | Jose Luis Diaz Mejia | Dispositivo y metodo de proteccion ampliada de lineas electricas. |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2249840B (en) * | 1990-11-13 | 1995-01-11 | Alireza Ghazi Hessami | Universal digital input channel |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3179930A (en) * | 1961-03-28 | 1965-04-20 | Cutler Hammer Inc | Circuit condition indicating systems |
US3505664A (en) * | 1967-07-07 | 1970-04-07 | Hubbell Inc Harvey | Switch condition indicator |
US3626248A (en) * | 1970-02-06 | 1971-12-07 | Struthers Dunn | Contact monitoring system |
US4191946A (en) * | 1977-10-20 | 1980-03-04 | Gonzalez Raymond J | Warning apparatus with a line integrity supervisory circuit |
-
1980
- 1980-12-09 GB GB8039358A patent/GB2089591B/en not_active Expired
-
1981
- 1981-12-09 DE DE8181305812T patent/DE3172734D1/de not_active Expired
- 1981-12-09 EP EP19810305812 patent/EP0054407B1/de not_active Expired
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3179930A (en) * | 1961-03-28 | 1965-04-20 | Cutler Hammer Inc | Circuit condition indicating systems |
US3505664A (en) * | 1967-07-07 | 1970-04-07 | Hubbell Inc Harvey | Switch condition indicator |
US3626248A (en) * | 1970-02-06 | 1971-12-07 | Struthers Dunn | Contact monitoring system |
US4191946A (en) * | 1977-10-20 | 1980-03-04 | Gonzalez Raymond J | Warning apparatus with a line integrity supervisory circuit |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2253065A1 (es) * | 2004-03-22 | 2006-05-16 | Jose Luis Diaz Mejia | Dispositivo y metodo de proteccion ampliada de lineas electricas. |
Also Published As
Publication number | Publication date |
---|---|
GB2089591B (en) | 1985-05-22 |
EP0054407B1 (de) | 1985-10-23 |
DE3172734D1 (en) | 1985-11-28 |
GB2089591A (en) | 1982-06-23 |
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Legal Events
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
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AK | Designated contracting states |
Designated state(s): BE DE FR IT NL SE |
|
17P | Request for examination filed |
Effective date: 19821216 |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: RESTBURY LIMITED |
|
ITF | It: translation for a ep patent filed |
Owner name: BARZANO' E ZANARDO ROMA S.P.A. |
|
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REF | Corresponds to: |
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