WO1990008441A1 - Circuit detecteur de terre - Google Patents
Circuit detecteur de terre Download PDFInfo
- Publication number
- WO1990008441A1 WO1990008441A1 PCT/JP1990/000036 JP9000036W WO9008441A1 WO 1990008441 A1 WO1990008441 A1 WO 1990008441A1 JP 9000036 W JP9000036 W JP 9000036W WO 9008441 A1 WO9008441 A1 WO 9008441A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- voltage
- ground fault
- power supply
- converter
- fault detection
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M19/00—Current supply arrangements for telephone systems
- H04M19/001—Current supply source at the exchanger providing current to substations
- H04M19/008—Using DC/DC converters
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M19/00—Current supply arrangements for telephone systems
- H04M19/001—Current supply source at the exchanger providing current to substations
- H04M19/006—Circuits for increasing the range of current supply source
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M3/00—Automatic or semi-automatic exchanges
- H04M3/22—Arrangements for supervision, monitoring or testing
- H04M3/26—Arrangements for supervision, monitoring or testing with means for applying test signals or for measuring
- H04M3/28—Automatic routine testing ; Fault testing; Installation testing; Test methods, test equipment or test arrangements therefor
- H04M3/30—Automatic routine testing ; Fault testing; Installation testing; Test methods, test equipment or test arrangements therefor for subscriber's lines, for the local loop
Definitions
- the present invention relates to a ground fault detection circuit for a long-distance subscriber circuit in a small-capacity digital electronic exchange (such as a private branch exchange). It relates to a ground fault detection circuit that has a protection function for long-distance subscriber circuits when stopped.
- the functions provided in the subscriber circuit used in the digital electronic exchange include power supply (B) and overvoltage protection, respectively.
- the present invention relates to a circuit that realizes ground fault detection, which is one of the monitoring functions (S).
- Ground faults are caused by uninsulated telephone wires accidentally coming into contact with grounded metal or ground during construction. This is because when a ground fault occurs, the current in the power supply circuit becomes twice as large as usual and consumes four times as much power as usual, causing a dangerous situation such as heat generation.
- large-capacity digital electronic exchanges such as central office exchanges
- PBXs small-capacity digital electronic exchanges
- PBXs PBXs
- PBXs PBXs
- a -24V power supply to supply power because the telephone line connecting the exchange and the telephone can be short.
- the telephone line becomes longer with a 24-V power supply, it will not be possible to supply sufficient talk current if the telephone line becomes longer, so that a longer-distance subscriber circuit requires a higher voltage, such as a voltage of 148 V. I have.
- a DC / DC converter is used in the power supply circuit of the subscriber circuit, and the voltage of 124 V is boosted to a voltage of 148 V.
- the circuit conditions are severe, so a feeder circuit using resistors and transformers is advantageous.
- the advantages of power supply by resistance are that it is not necessary to consider the dynamic range required for the power supply plane by transistor circuit, and that current can flow in both directions without distortion. In other words, it is difficult to use the constant current protection circuit method often used in power supply circuits with transistor circuits in power supply circuits in long-distance subscriber circuits.
- Figure 1 shows an image configuration diagram of a ground fault detection image path of a subscriber circuit that uses a conventional DCZDC converter as a power supply circuit.
- 1 is a DCZDC converter
- 2 is a comparator
- 3 is a power supply transformer
- 4 is a subscriber telephone.
- DCZDC converter 1 has a — 24 V voltage (exchanger This is a DC transformer circuit for boosting the system power supply to a voltage of 148 V.
- Comparator 2 is a circuit that detects a ground fault by comparing it with a reference voltage and sends a monitoring signal to the control unit of the exchange. When a ground fault occurs in the subscriber line, if the line resistance is 0, the feed current I flows twice as much as normal. Therefore, when the voltage of DC / DC converter 1 is fixed at 148 V, the supply current value increases. Further, the ground fault detection voltage V E becomes earthed, the signal of "1" to the switch controller comparator 2 is inverted is sent, and sends an alarm.
- the DC / DC converter 1 keeps the power supply for 48 V as it is—because it continues to supply 48 V, the power supply resistances R T and R R withstand four times the power. Therefore, the DC / DC converter 1 must be configured to withstand twice the current. As a result, not only will the price rise, but also the size of the circuit components will increase and the restrictions on component mounting will increase.
- a main object of the present invention is to provide a ground fault detection circuit that solves the above problems.
- the object of the present invention is to supply 148 V voltage to a power supply circuit of a long-distance subscriber circuit by using a DC / DC converter, and to supply 148 V voltage at the time of ground fault detection.
- a DC / DC converter By switching to 24 V voltage, the ground fault detection state is maintained, the current capacity at the time of ground fault is reduced, and the circuit components are reduced in size, weight, and economy.
- Another object of the present invention is to provide a ground fault detection circuit.
- the present invention is a ground fault detection circuit for a long-distance subscriber circuit in a small-capacity digital electronic exchange (such as a private branch exchange).
- This ground fault detection circuit has the following elements.
- the ground fault detection circuit includes a DC / DC converter that converts a low potential to a high potential as a power supply for power supply, and a comparator that detects occurrence of a ground fault.
- the comparison winding compares a reference voltage obtained by dividing the high voltage converted by the DCDC converter with a ground fault detection voltage, and when a ground fault is detected, sends a ground fault monitoring signal to the exchange control unit. At the same time, a stop signal for stopping the DCZDC converter is transmitted to the DCZDC converter.
- Fig. 1 shows a conventional ground fault detection surface
- Fig. 2 shows a basic configuration of the present invention:
- FIG. 3 is a diagram showing a feed current characteristic of a line resistance according to the present invention
- FIG. 4 is a diagram showing an embodiment of the present invention.
- 1 is a DCZDC converter
- 2 is a comparator
- 3 is a transformer for power supply
- 4 is a subscriber telephone. Is shown.
- Reference voltage V th of the comparator 2 is created by dividing a resistor R Z and R 3 from the DC Roh DC co down converter 1 on the output side one 4 8 V, is supplied to the comparator 2 + terminals
- ground fault detection use voltage V E is the feed resistance R R and dividing resistor R. from DCZDC converter 1 on the output side one 4 8 V , And are supplied to one terminal of the comparator 2. If there is a ground fault in the tip line or Tng line of the subscriber line, the power supply resistance RH and the voltage division resistance R are used. A ground is generated between the two, and one terminal of the comparator 2 becomes ground, and the comparator 2 inverts and sends a ground fault monitoring signal to the exchange control unit.
- FIG. 3 shows a characteristic diagram of the relationship between the line resistance R of the subscriber line connected to the subscriber telephone 4 and the supply current I.
- the present invention uses this principle. And applies to long distance subscribers with large line resistance. If a ground fault occurs, the output voltage of the DC / DC converter is switched from 148 V to 124 V by inverting comparator 2. . Even if a ground fault occurs, the supply current is only half of the case of 148 V because the voltage is 124 V, and the ground fault monitoring voltage V E sent to the comparator 2 and the reference voltage V th are also relative. As a result, the detection circuit for the comparator 2 does not change, and the monitoring signal for the exchange control unit is maintained in the state of being transmitted.
- the power supply of the DCZDC converter is simply returned from -48 V to 124 V, and the comparator 2 can maintain the abnormal voltage detection circuit, and the circuit element can be maintained.
- the child can also accommodate long-distance subscribers without using special power-bearing elements.
- the threshold current at the voltage of 148 V when the DC / DC converter is operating that is, the current value of the power supply circuit that flows when the comparator is inverted is denoted by I A , - if the teeth threshold current at 2 4 V voltage and IB, I a is about twice the 0 current value IB, in accordance with the supply current magnitude line resistance Naru rather small if single 4 8 V voltage
- I A the threshold current at the voltage of 148 V when the DC / DC converter is operating
- I A the current value of the power supply circuit that flows when the comparator is inverted
- FIG. 4 is a block diagram of a ground fault detection circuit according to the present invention.
- 1 is a DC / DC converter
- 2 is a comparator
- 3 is a power supply transformer
- 4 is a subscriber telephone.
- the feed resistances R ⁇ and R R are 330 ⁇ , respectively, and the voltage dividing resistance R for ground fault detection. , Are 33 ⁇ , 11 1 ⁇ , the reference voltage dividing resistors Rz , R3 are 68 ⁇ , 10 ⁇ , and the reference voltage Vt is 6 V, — 3 V reference voltage with 24 V power supply.
- the configuration of the DC converter 1 includes a switching regulator element Q, an on / off signal receiving section for controlling the switching regulator element Q, a coil for boosting the voltage, and a rectifier circuit. It consists of a capacitor and a diode.
- This type of configuration is generally non-powered DC / It is called DC converter.
- an on-off signal is given to the gate of the switching regulator element Q, the DC voltage of 124 V is switched at a duty of 50%, and the output voltage is converted to 148 V.
- the ground fault occurrence monitoring signal “ ⁇ ” arrives from the comparator 2
- the on / off signal is mask-controlled by the gate element, and the control signal for the switching element Q is not transmitted. As a result, the switching regulator element Q is turned off.
- the diode and coil are simply connected in series, so that the output will be 24 V, and the power supply circuit will be supplied with 24 V voltage.
- the reference voltage V th of the comparator 2 is also becomes 3 V, the comparator 2 to halved voltage V E for ground fault detecting remain inverted to maintain the operating state of the switch control unit.
- the power supply circuit - for 2 4 V voltage is supplied, ground by requires at a current value of the feed resistors R R about 6 0 m A also remains a current flows', the process maintainer The alarm condition can be maintained until it is performed.
- the voltage of 148 V is reduced to a voltage of 24 V when a ground fault is detected.
- the ground fault detection status by switching to You can carry it.
- circuit components can be made smaller, lighter, and more economical.
- the present invention is suitable for constructing a long-distance subscriber circuit.
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Devices For Supply Of Signal Current (AREA)
- Monitoring And Testing Of Exchanges (AREA)
- Emergency Protection Circuit Devices (AREA)
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP90901688A EP0425675B1 (en) | 1989-01-19 | 1990-01-12 | Ground fault detecting circuit for subscriber lines |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1/12612 | 1989-01-19 | ||
JP1261289 | 1989-01-19 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1990008441A1 true WO1990008441A1 (fr) | 1990-07-26 |
Family
ID=11810193
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP1990/000036 WO1990008441A1 (fr) | 1989-01-19 | 1990-01-12 | Circuit detecteur de terre |
Country Status (5)
Country | Link |
---|---|
US (1) | US5113426A (ja) |
EP (1) | EP0425675B1 (ja) |
AU (1) | AU623968B2 (ja) |
CA (1) | CA2025014C (ja) |
WO (1) | WO1990008441A1 (ja) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5103387A (en) * | 1991-01-31 | 1992-04-07 | Northern Telecom Limited | High voltage converter |
DE69229268T2 (de) * | 1992-04-03 | 1999-09-23 | Northern Telecom Ltd | Schnittstellenschaltung mit spannungsumschaltung für eine fernsprechleitung |
US5436953A (en) * | 1993-07-02 | 1995-07-25 | Northern Telecom Limited | Digital longitudinal balance measurement |
US5515417A (en) * | 1994-06-29 | 1996-05-07 | Harris Corporation | Ground key detector for a SLIC |
FI112729B (fi) * | 1994-08-23 | 2003-12-31 | Nokia Corp | Menetelmä vikaantuneen yksikön elvyttämiseksi sekä elvytysjärjestelmä |
US5659610A (en) * | 1994-09-28 | 1997-08-19 | Lucent Technologies Inc. | Battery feed circuit |
US5862200A (en) * | 1996-07-16 | 1999-01-19 | Teltrend, Inc. | Ground fault detector for T1 span equipment |
US6999561B2 (en) * | 2003-03-31 | 2006-02-14 | Adtran Inc. | Method of detecting remote ground condition |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57109017A (en) * | 1980-12-26 | 1982-07-07 | Fujitsu Ltd | Protecting circuit for boosting type switching regulator |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3781480A (en) * | 1970-11-10 | 1973-12-25 | Wescom | Loop extender |
FR2374795A1 (fr) * | 1976-12-17 | 1978-07-13 | Jeumont Schneider | Equipement de ligne d'abonne pour central telephonique |
DE2911517C2 (de) * | 1979-03-23 | 1981-07-09 | Siemens AG, 1000 Berlin und 8000 München | Teilnehmeranschlußschaltung mit Erdtasten- und Isolationsfehlerindikation |
JPS5737967A (en) * | 1980-08-15 | 1982-03-02 | Nec Corp | Talking current supply protecting circuit |
JPS5848559A (ja) * | 1981-09-18 | 1983-03-22 | Nec Corp | 通話電流供給方式 |
JPS58151165A (ja) * | 1982-03-04 | 1983-09-08 | Fujitsu Ltd | 地絡検出回路 |
JPH071899B2 (ja) * | 1986-01-22 | 1995-01-11 | 株式会社日立製作所 | 検出回路 |
CA1333189C (en) * | 1987-06-17 | 1994-11-22 | Toshiro Tojo | Protection circuit for battery feed circuit |
LU86987A1 (fr) * | 1987-09-07 | 1989-04-06 | Glaverbel | Microbilles de verre a proprietes bacteriostatiques,procede de fabrication de telles microbilles |
IT1223618B (it) * | 1987-12-28 | 1990-09-29 | Sgs Thomson Microelectronics | Circuito di interfaccia tra linea telefonica d'utente ed organi di comando centrale, con limitazione del consumo di corrente in caso di cavo a terra |
-
1990
- 1990-01-12 AU AU48251/90A patent/AU623968B2/en not_active Ceased
- 1990-01-12 CA CA002025014A patent/CA2025014C/en not_active Expired - Fee Related
- 1990-01-12 US US07/573,130 patent/US5113426A/en not_active Expired - Fee Related
- 1990-01-12 EP EP90901688A patent/EP0425675B1/en not_active Expired - Lifetime
- 1990-01-12 WO PCT/JP1990/000036 patent/WO1990008441A1/ja active IP Right Grant
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57109017A (en) * | 1980-12-26 | 1982-07-07 | Fujitsu Ltd | Protecting circuit for boosting type switching regulator |
Non-Patent Citations (1)
Title |
---|
See also references of EP0425675A4 * |
Also Published As
Publication number | Publication date |
---|---|
AU623968B2 (en) | 1992-05-28 |
US5113426A (en) | 1992-05-12 |
EP0425675B1 (en) | 1996-07-10 |
CA2025014C (en) | 1994-11-22 |
EP0425675A4 (en) | 1993-01-13 |
CA2025014A1 (en) | 1990-07-20 |
AU4825190A (en) | 1990-08-13 |
EP0425675A1 (en) | 1991-05-08 |
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