EP1455369A1 - Fehlerstromvorrichtung - Google Patents

Fehlerstromvorrichtung Download PDF

Info

Publication number
EP1455369A1
EP1455369A1 EP04075652A EP04075652A EP1455369A1 EP 1455369 A1 EP1455369 A1 EP 1455369A1 EP 04075652 A EP04075652 A EP 04075652A EP 04075652 A EP04075652 A EP 04075652A EP 1455369 A1 EP1455369 A1 EP 1455369A1
Authority
EP
European Patent Office
Prior art keywords
residual current
windings
wound
winding
current
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.)
Withdrawn
Application number
EP04075652A
Other languages
English (en)
French (fr)
Inventor
Patrick Ward
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Atreus Enterprises Ltd
Original Assignee
Atreus Enterprises Ltd
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 Atreus Enterprises Ltd filed Critical Atreus Enterprises Ltd
Publication of EP1455369A1 publication Critical patent/EP1455369A1/de
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase ac
    • H01F38/28—Current transformers
    • H01F38/30—Constructions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H83/00—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current
    • H01H83/14—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by imbalance of two or more currents or voltages, e.g. for differential protection
    • H01H83/144—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by imbalance of two or more currents or voltages, e.g. for differential protection with differential transformer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F17/00—Fixed inductances of the signal type 
    • H01F17/04—Fixed inductances of the signal type  with magnetic core
    • H01F17/045—Fixed inductances of the signal type  with magnetic core with core of cylindric geometry and coil wound along its longitudinal axis, i.e. rod or drum core

Definitions

  • This invention relates to a residual current device (RCD).
  • an RCD is defined as any device which can detect a residual current in an A.C. electricity supply, such as an A.C. mains, and initiate an action in response to such detection. Such action may be the opening of contacts in the supply conductors, or the raising of an alarm.
  • Detection of the residual current can be achieved by various means, but the most common means is by use of a differential current transformer.
  • a conventional RCD used for an A.C. mains supply having live L, neutral N and earth E conductors is shown in Fig. 1.
  • the conventional RCD comprises a differential current transformer CT having a toroidal core 10, primary windings W1 and W2 connected respectively to the live L and neutral N conductors of the mains supply, and a secondary winding W3.
  • the primary and secondary windings can comprise one or more turns, as required.
  • a current flowing in either one of the primary windings W1, W2 will induce a current in the secondary winding W3, and when currents flow in both primary windings the current induced in the secondary winding W3 will be the vector sum of the currents individually induced therein by the primary windings.
  • the secondary winding is also sometimes referred to as a sense winding because it senses the differential current in the primary windings.
  • the net current flowing in the secondary winding W3 flows through the winding 16 of a solenoid-operated device (such as a permanent magnet relay, not shown) coupled to the contacts 12A, 12B in known manner.
  • a solenoid-operated device such as a permanent magnet relay, not shown
  • the net current induced in the secondary winding W3 will be sufficient to actuate the solenoid-operated device, this in turn opening the contacts 12A, 12B and disconnecting the electricity supply from the load 14.
  • the circuit shown in Fig. 1 may be adapted to multiphase electricity supplies by providing more primary windings.
  • the net current flowing in the secondary winding will correspond to the vector sum of the currents individually induced by all the primary windings, and will be arranged to be zero in the absence of a residual current.
  • the toroidal differential CT as described above has been used for many years in RCD applications. It has the advantages of being simple, compact and reliable.
  • a key disadvantage of the toroidal differential CT is that it does not lend itself to automated assembly or mass production.
  • the primary and secondary windings must be fitted to each CT on an individual basis which precludes the possibility of assembling several CTs simultaneously. This problem can be compounded in cases where multiple primary turns are required to produce a desired secondary output from a lower differential current, or in cases where the primary conductors need to have a large cross sectional area to accommodate higher load current levels, etc.
  • Factors such as core size and primary conductor size limit the number of turns that can be applied to the primary windings.
  • toroidal differential CTs Assembly of toroidal differential CTs is a labour intensive operation which adds considerably to manufacturing time and cost of voltage independent RCDs.
  • many high volume manufacturers of such CTs have transferred production to locations where labour costs are low. This produces a temporary respite, but over time labour costs rise in all locations. It is generally accepted that automated assembly of the CT would be the optimum means of achieving low cost manufacture. Automated assembly would also provide for cost reductions for even relatively low volume production.
  • the present invention provides a residual current device comprising a current transformer having a plurality of primary windings each for connection to a respective conductor of an A.C. electricity supply and a secondary winding into which a current is induced which is a function of the currents flowing in the primary windings, the current induced in the secondary winding initiating an action in response to a residual current above a predetermined threshold, wherein each of the primary and secondary windings is wound on a ferromagnetic element of which at least the portion bearing the winding has a substantially linear axis.
  • the primary and secondary windings are arranged such that the net current induced in the secondary winding is zero in the absence of a residual current, so that the presence of a net induced current above a certain level, corresponding to the predetermined level of residual current, initiates the action.
  • the windings it is equally possible, in particular for so-called voltage dependent RCDs (see below), for the windings to be arranged such that a net induced current flows in the case of a zero residual current, and reduces as the residual current increases, so that a zero induced current would be indicative of the predetermined level of residual current.
  • Other arrangements are also possible.
  • the windings are wound on at least two ferromagnetic elements forming a closed magnetic circuit.
  • the primary and secondary windings are wound on a common element having a linear axis.
  • the residual current device is a voltage independent type wherein the current induced in the secondary winding operates a solenoid to disconnect the electricity supply in response to a residual current above a predetermined level.
  • Fig. 2 shows an embodiment of the invention in which components the same or equivalent to those of Fig. 1 have the same reference numerals (the earth conductor E is not shown for convenience).
  • the windings W1, W2 and W3 are wound on a common ferromagnetic core or former 20 having a substantially linear (i.e. non-curved) axis 22.
  • the net current induced in the secondary winding W3 and flowing in the winding 16 will be sufficient to actuate the solenoid-operated device to opening the contacts 12A, 12B and disconnect the electricity supply from the load 14.
  • the turns ratios of W1, W2 and W3 can be arranged to achieve a desired secondary output for a given difference in primary currents.
  • the windings W1, W2 and W3 can be wound on a conventional bobbin or mandrill to provide for a conventional coil form as normally used on conventional transformer and solenoid windings.
  • the individual windings can be produced by automated means which facilitates the production of numerous windings simultaneously.
  • the simultaneous production of up to thirty windings by automated means is not uncommon.
  • due to the rigidity of the wire in the primary windings these windings can be formed and produced without the need for a bobbin.
  • the performance or efficiency of the RCD can be improved by closing the magnetic path with an external frame 24, as shown in Fig. 3.
  • the primary windings W1 and W2 are wound on a large diameter bobbin 26 having a linear axial bore 28.
  • the secondary winding W3, shown in dashed lines in Fig. 4(a), is wound on a smaller diameter bobbin 30 also having a linear axial bore 32.
  • a ferromagnetic core 34 is inserted coaxially into the bore 32 of the smaller diameter bobbin 30 and the latter is in turn inserted coaxially into the axial bore 28 of the large diameter bobbin 26.
  • a ferromagnetic core is in the form of a closed magnetic circuit, in the present case a rectangle.
  • the core is formed of a generally U-shaped ferromagnetic member 40 having opposite substantially parallel straight elongated limbs 40a, 40b and a substantially straight elongated member 42 extending between the free ends of the U-shaped member 40. Accordingly, all the elements 40a, 40b and 42 have respective linear axes.
  • the base 40c of the U-shaped member 40 is also shown as being straight, but this is not necessary unless a winding is wound on it, which is not the case in the present embodiment. Therefore, the base 40c could be curved so that the member 40 as a whole assumes the traditional "U" shape with curved base.
  • the members 40 and 42 could each comprise a single metal part, or comprise laminations stacked on top of each other.
  • the primary windings W1 and W2 are wound on the limbs 40a and 40b respectively, while the secondary winding W3 is wound on the member 42.
  • the winding operations and placement of the windings on the respective members takes place before the straight member 42 is assembled to the member 40.
  • the connections of the windings W1 to W3 into the overall circuit of the residual current device is as shown in Fig. 2.
  • the embodiments of the invention can be adapted to multiphase electricity supplies by providing more primary windings and arranging that the net current flowing in the secondary winding is zero in the absence of a residual current.
  • one or more air gaps may be intentionally provided within the magnetic path comprising of the core and frame so as to facilitate calibration of the electromagnetic characteristics or performance of the transformer.
  • the various primary and secondary windings be directly wound onto the ferromagnetic elements of the final residual current device. It is alternatively possible to wind each winding on a temporary former, and then transfer the winding to the respective ferromagnetic element by sliding it off the former and onto the element. If the former is itself hollow, the transfer can be done without removing the winding from the former, simply by sliding the former over the ferromagnetic element.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transformers For Measuring Instruments (AREA)
EP04075652A 2003-03-06 2004-03-02 Fehlerstromvorrichtung Withdrawn EP1455369A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IE20030163 2003-03-06
IE20030163 2003-03-06

Publications (1)

Publication Number Publication Date
EP1455369A1 true EP1455369A1 (de) 2004-09-08

Family

ID=32800551

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04075652A Withdrawn EP1455369A1 (de) 2003-03-06 2004-03-02 Fehlerstromvorrichtung

Country Status (1)

Country Link
EP (1) EP1455369A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102364533A (zh) * 2011-07-07 2012-02-29 安徽海圣电气有限公司 全监测型剩余电流式电气火灾监控探测器

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6504691B1 (en) * 1999-07-13 2003-01-07 Kabushiki Kaisha Sanyo Denki Seisa Kusho Safety enhanced transformer circuit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6504691B1 (en) * 1999-07-13 2003-01-07 Kabushiki Kaisha Sanyo Denki Seisa Kusho Safety enhanced transformer circuit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1996, no. 01 31 January 1996 (1996-01-31) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102364533A (zh) * 2011-07-07 2012-02-29 安徽海圣电气有限公司 全监测型剩余电流式电气火灾监控探测器
CN102364533B (zh) * 2011-07-07 2013-11-06 安徽海圣电气有限公司 全监测型剩余电流式电气火灾监控探测器

Similar Documents

Publication Publication Date Title
US4295111A (en) Low temperature latching solenoid
US20100118451A1 (en) Multiple-pole circuit breaker with shared current sensor for arcing fault detection
CN101295579A (zh) 电流传感装置
EP2261944A2 (de) Leistungsschalter
CA2591103C (en) Aluminum wound transformer
US5327112A (en) Electromagnetic actuator of the type of a relay
US6181125B1 (en) Combination apparatus of a distribution transformer and switches
FI97428C (fi) Kytkentäelin sähköistä kytkintä varten ja tällä kytkentäelimellä varustettu sähköinen kytkin
US6100783A (en) Energy efficient hybrid core
EP1455369A1 (de) Fehlerstromvorrichtung
EP0984462A3 (de) Elektrischer Transformator
US5886606A (en) Circuit breaker
JP3498055B2 (ja) 電力変成器機能及び即時引外し機能を果す装置
US6714396B2 (en) Undervoltage tripping device
IES20070918A2 (en) A current transformer
FI91200C (fi) Sähkömagneettinen kytkin
US5999385A (en) Ground fault circuit breaker
GB2251741A (en) Rapid response ground fault circuit interrupter
JPH05266779A (ja) 回路遮断器の引外し装置
JP3106977B2 (ja) 回路遮断器
CA1096426A (en) Electromagnet an extremely inverse time overcurrent protective relay
KR100737061B1 (ko) 이중 정격 전류 변압기 회로
GB2074380A (en) A fault current circuit breaker
JPH03233824A (ja) 漏電遮断器
JPS62222607A (ja) 制御回路用電流検出素子

Legal Events

Date Code Title Description
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

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL LT LV MK

17P Request for examination filed

Effective date: 20050308

AKX Designation fees paid

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PL PT RO SE SI SK TR

17Q First examination report despatched

Effective date: 20091013

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20100424