US1748724A - Knife switch - Google Patents

Knife switch Download PDF

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Publication number
US1748724A
US1748724A US67753A US6775325A US1748724A US 1748724 A US1748724 A US 1748724A US 67753 A US67753 A US 67753A US 6775325 A US6775325 A US 6775325A US 1748724 A US1748724 A US 1748724A
Authority
US
United States
Prior art keywords
switch
blade
pin
contact
springs
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.)
Expired - Lifetime
Application number
US67753A
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English (en)
Inventor
Morger Otto
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.)
BBC Brown Boveri AG Germany
BBC Brown Boveri France SA
Original Assignee
BBC Brown Boveri France SA
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 BBC Brown Boveri France SA filed Critical BBC Brown Boveri France SA
Application granted granted Critical
Publication of US1748724A publication Critical patent/US1748724A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/50—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position
    • H01H1/54—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position by magnetic force

Definitions

  • This invention relates to knife switches and the like and it has for its general object to provide a switch which will not open on the passage of an exceptionally large current, such as may result from a short-circuit.
  • Knife switches may be caused to open automatically on the passage of a large current due to a short-circuit, by reason of the powerful electro-dynamic forces set up, and to 0 prevent this it has hitherto been usual to employ pawls arranged in various ways. A1 rangements of this kind, however, complicate and increase the cost of construction and have been found in practice not to be entirely reliable.
  • the present invention contemplates using the increase of electro-dynamic force that occurs on the passage of a short-circuit current to assist in holding closed the switch.
  • these forces acting in the contact parts are utilized to hold closed the blade of the switch.
  • FIG. 1 shows a longitudinal elevation of one form
  • Figs. 2 and 3 show end elevations of modified forms
  • Fig. 4 shows a longitudinal elevation of part of a switch of a further modified form and Fig. 5 a plan thereof, and
  • Fig. 6 an end elevation of a further modi' tied form.
  • the blade 6 is provided with a slot which at its inner end 2' bends towards the front edge of the blade and which embraces a pin or screw 0 on the contact member a when the switch is closed.
  • One or both of the supporting insulators f and g I is or are flexibly mounted so as to be slightl movable toward and from the other, for example, ona cork or rubber disc or on a support provided with a oint.
  • the insulator f is shown mounted on a panel j by means of a rod which passes through a tapered hole Zin the panel, the said tapered hole permitting a slight movement of the insulator.
  • the contact members consist of springs a bent inwardly in the form of a loop or loops, the current entering at the inner end of the loop and leaving at the outer end. Since the current induces forces in the spring loops at tending to expand or spread the loops, the movable arms thereof will be pressed against the blade Z) with a pressure which increases with the strength of the current.
  • the springs a are arranged on either side of the blade I) and supporting means such as the screw or pin 0 shown in Fig. 2, or the rigid lateral abutments 6 shown in Fig. 3, prevents the outer arms of the loops from moving outwardly under the action of the heavy currents so that the whole of the loopexpanding pressure produced by the electrodynamic force is utilized as frictional pressure against the blade Z).
  • the blade slot may also be such as to enable it to engage the screw or pin 0 retentively, in a manner similar to that of the arrangement illustrated in Fig. 1. Therefore, when the switch is closed, the blade limits movement of the contact members in the longitudinal di rection of the blade as the electro-dynaniic force which tends to force them apart on the passage of a short-circuit current will be transferred to the blade and taken up by it as a tensile stress, thereby relieving the insulator mountings of the pressure.
  • the blade 6 is provided with lateral retaining members It at its free end, so arranged as to overlap the outer margin of the contact member a; when the switch is closed. lVhen the contact member is forced outwardly on the passage of an abnormal current, the contact member is forcibly pressed the retaining member it, and the blade thcreq retained in engagement with the contact member.
  • This feature may be combined with the loop arrangement illustrated in Figs. 2 and 3.
  • the movable switch-closing member is formed with two blades 7) which are connected in parallel spaced relationship by spacing bolts or pins 0, and the contact member a is formed as a double loop with its free arms toward the outer sides.
  • the blades close against the outer arms of the loop against their spring tension.
  • the electrodynamic forces tend to spread the loops, thus pressing the outer arms thereof against the blades with increased force, the blades being held against spreading by the spacer bolts 0.
  • the feature iilustrated in Figs. 4 and 5 may be combined with this construction.
  • the switch in addition to the movable blade or switclrclosing member, the switch has a contact or terminal member which is shiftable by the electrodynamic forces produced by a current passing the switch, so as to exert mechanical pressure on a movable switchclosing member in a fashion to retain the same in engagement with the contact memher.
  • a knife switch having a contact, a pin therethrough, and a blade having a slot to receive the pin such that on the passage of a short-circuit current the forces set up act to increase the pressure between the pin and the surface of the slot to oppose the opening of the switch.
  • a knife switch having a contact, a pin therethrough, and a blade having a slot to receive the pin and shaped to constitute a catch such that on the passage of a short-circuit current the forces set up act to increase the pressure between the pin and the surface of the slot to oppose the openin of the switch.
  • a knife switch having a contact consisting of a pair of springs each bent in the form of a loop with their free ends adjacent, a pin through the springs to support their other ends and prevent movement thereof, and a blade movable between the free ends of the springs and having a slot to receive the pin such that on the passage of a short-circuit current the forces set up act to increase the pressure between surfaces of the springs and the blade and between the pin and the surface of the slot to oppose the opening of the switch.
  • a knife switch having a contact mounted to have slight movement and consisting of a pair of springs each bent in the form of a loop with their free ends adjacent, a pin through the springs to support their other ends and prevent movement thereof, and a 'blade movable between the free ends of the springs and having a slot to engage the pin such that on the passage of a short-circuit current the forces set up act to increase the pressure between surfaces of the springs and the blade and between the pin and the surface of the slot to oppose the opening of the switch.
  • a knife switch having a contact consist ing of a pair of springs each bent in the form of a loop with their free ends adjacent, a in through the springs to support their ot er ends and prevent movement thereof, a blade movable between the free ends of the springs and having a slot of a size to receive the pin closely such that on the passage of a shortcircuit current the force set up tending to bend the terminals of the switch outwardly is taken up by the blade as a tensile stress thereby relieving the supporting insulators that carry the stationary contacts.
  • switch apparatus complementary contact elements disposed for relative movement into and out of contacting relation with rescpect to each other, means supporting one of said elements and providing for bodily movement of the same incident to occurrence of abnormal current conditions in said apparatus when said elements are operatively engaged, and means operable incident to such movement to provide for retention of said elements in engaged relation.

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  • Mechanisms For Operating Contacts (AREA)
  • Contacts (AREA)
US67753A 1924-12-08 1925-11-09 Knife switch Expired - Lifetime US1748724A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE244058X 1924-12-08

Publications (1)

Publication Number Publication Date
US1748724A true US1748724A (en) 1930-02-25

Family

ID=5923969

Family Applications (1)

Application Number Title Priority Date Filing Date
US67753A Expired - Lifetime US1748724A (en) 1924-12-08 1925-11-09 Knife switch

Country Status (4)

Country Link
US (1) US1748724A (de)
FR (1) FR605110A (de)
GB (1) GB244058A (de)
NL (1) NL18953C (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2759076A (en) * 1954-06-25 1956-08-14 Southern States Equipment Corp Electric switch
US2806110A (en) * 1954-05-26 1957-09-10 Westinghouse Electric Corp Circuit interrupters
US3249729A (en) * 1963-10-18 1966-05-03 Gen Electric Electric circuit breaker wherein the operation of separable arcing contacts is dependent on the magnitude of current in the main contacts
US20200168412A1 (en) * 2018-11-28 2020-05-28 Xuji (Xiamen) Intelligent Switchgear Manufacturing Co., Ltd. Knife switch

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2806110A (en) * 1954-05-26 1957-09-10 Westinghouse Electric Corp Circuit interrupters
US2759076A (en) * 1954-06-25 1956-08-14 Southern States Equipment Corp Electric switch
US3249729A (en) * 1963-10-18 1966-05-03 Gen Electric Electric circuit breaker wherein the operation of separable arcing contacts is dependent on the magnitude of current in the main contacts
US20200168412A1 (en) * 2018-11-28 2020-05-28 Xuji (Xiamen) Intelligent Switchgear Manufacturing Co., Ltd. Knife switch
US10910177B2 (en) * 2018-11-28 2021-02-02 Xuji (Xiamen) Intelligent Switchgear Manufacturing Co., Ltd. Knife switch

Also Published As

Publication number Publication date
FR605110A (fr) 1926-05-20
GB244058A (en) 1926-05-13
NL18953C (de)

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