US3543096A - Method and apparatus for sensing and correcting an overloaded electrical circuit - Google Patents

Method and apparatus for sensing and correcting an overloaded electrical circuit Download PDF

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Publication number
US3543096A
US3543096A US703167A US3543096DA US3543096A US 3543096 A US3543096 A US 3543096A US 703167 A US703167 A US 703167A US 3543096D A US3543096D A US 3543096DA US 3543096 A US3543096 A US 3543096A
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United States
Prior art keywords
circuit breaker
power supply
switching means
supply unit
key
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Expired - Lifetime
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US703167A
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English (en)
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Edward F Bedford
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Systems Electronics Inc
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Systems Electronics Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00

Definitions

  • a method and apparatus for sensing and correcting an overloaded electrical circuit including a power supply unit which is defined by an incoming line having a positive and negative side adapted to be connected to a source of electrical power, means to vary the voltage, and output means for connecting electrical apparatus to the power supply unit.
  • the apparatus of this invention is comprised of a circuit breaker connected in series with at least one side of the incoming line and having internal switching means adapted to open in the event of an overloaded condition of the incoming line.
  • the circuit breaker is provided with an external reset arm adapted to reset the internal switching means to a closed position.
  • a key operated tumbler lock including a key plug rotatable in a lock cylinder and a keyway is attached to a panel of the power supply unit such that the keyway is accessible from the exterior of the power supply unit.
  • the key plug of the tumbler lock is interconnected to the external reset arm of the circuit breaker by means of a connecting arm and pin linkage.
  • the internal switching means of the circuit breaker may be reset by a key inserted in the keyway.
  • the connection between the external reset arm and the internal switching means of the circuit breaker is of the lost motion type permitting the internal switching means to open independently of the external reset arm and the key plug.
  • the method of this invention comprises the steps of:
  • This invention relates to a method and apparatus for sensing and correcting an overloaded electrical circuit.
  • this invention relates to a method and apparatus for sensing and correcting an electrical circuit assembled by a student in a laboratory.
  • a power supply unit In science laboratories of high schools and colleges, it is customary to conduct experiments involving electrical apparatus wherein the student is permitted to complete an electrical circuit and, after connecting the circuit to a source of electrical power, to observe certain phenomena.
  • a power supply unit Common to practically all experiments involving an electrical circuit is a power supply unit.
  • Power supply units may take several dififerent forms and may include various features and accessories depending upon the end use to which it will be put. However, common to all power supply units will be several basic components including an incoming line adapted to be connected to a source of electrical power, one or more potentiometers adapted to vary the voltage, and an outlet to which may be connected suitable electrical apparatus.
  • the power supply unit may also include a circuit breaker adapted to open in the event of an overloaded condition of the circuit assembled by the student.
  • Known prior art power supply units incorporating a circuit breaker include some form of manual reset button or toggle switch means whereby the student can readily reset the circuit breaker to a closed position at his option. It has been found, however, that permitting the student to reset the circuit breaker on his power supply unit may be detrimental to expensive laboratory equipment in that the student may not be capable of determining the source of a short circuit.
  • the apparatus and method of this invention provide for sensing and correcting of an overloaded circuit by means of a key operated circuit breaker located within a laboratory power supply unit.
  • Key operation of the circuit breaker permits the instructor to check on student work in the event of a short circuit. With the instructor maintaining possession of the key, the student must call to the attention of the instructor any short circuit condition since the instructor is the only individual capable of resetting the circuit breaker. Thus, the instructor is assured of having an opportunity toinspect the circuit after each occurrence of an overloaded condition.
  • the apparatus of this invention is comprised of a key operated tumbler lock including a key plug rotatable in a lock cylinder and a keyway.
  • the tumbler lock is located in a power supply unit comprising an incoming line adapted to be connected to a source of electrical power, potentiometer means to vary the voltage of the power source, and output means for connecting suitable electrical apparatus to the power supply unit.
  • a circuit breaker is mounted within the power supply unit and is connected in series with at least one side of the incoming line. Internal switching means are provided in the circuit breaker adapted to open in the event of an overloaded condition of the incoming line.
  • the circuit breaker further includes an external reset arm adapted to reset the internal switching means to a closed position.
  • Interconnecting linkage means is provided between the key plug of the tumbler lock and the external reset arm whereby the internal switching means of the circuit breaker may be reset by a key inserted in the keyway of the tumbler lock.
  • lost motion means is provided between the internal switching means and the key plug.
  • the method of this invention comprises the steps of:
  • a key operated tumbler lock including a key plug rotatable in a lock cylinder.
  • the tumbler lock is mounted on a power supply unit including an incoming line adapted to be connected to a source of electrical power, potentiometer means to vary the voltage, and output means'for connecting electrical apparatus.
  • the tumbler lock is mounted on the power supply unit such that the lock keyway is accessible from the exterior of the unit.
  • FIG. 1 is a perspective view of a laboratory power supply unit and showing the tumbler lock, an element of the apparatus of this invention, mounted thereon,
  • FIG. 2 is an end elevation view of the circuit breaker and tumbler lock of this invention
  • FIG. 3 is a top view, partly in section, of the circuit breaker and tumbler lock as mounted to the face of a power supply unit and showing the circuit breaker in the closed or on position,
  • FIG. 4 is a top view similar to FIG. 3 and showing the circuit breaker in an open or off position
  • FIG. 5 is a view taken along the line 5-5 of FIG. 3.
  • a laboratory power supply unit 10 including a case 12 and a front panel 14.
  • Panel 14 may be secured to case 12 by means of fasteners 16 or other connecting means well known to those skilled in the art.
  • a pair of front panel handles 18 vare provided for ease of installation of the power supply unit.
  • Mounted on the face of panel 14 are a plurality of control knobs 20, 22 and 24, outlets 26, 28, output jacks 30, 32 and 34 and an indicator light 36.
  • the control knobs 20-24 function to vary the output of the power supply at the output jacks 30-34.
  • One or more potentiometers are located within the case 12 of the power supply unit and are controlled by the knobs 20-24.
  • the indicator light 36 serves to visually indicate that the power supply unit is supplying power at the outlet jacks.
  • the power supply unit as shown in FIG. 1 illustrates a typical laboratory unit to which the apparatus and method of this invention may be applied.
  • the power supply unit as shown in FIG. 1 should not be considered as limiting to this invention as many combinations of switches, outlets, potentiometers, output jacks, indicator lights, and meters are possible within a power supply unit depending upon the end result desired.
  • This invention broadly relates to a basic laboratory power supply unit including an incoming line adapted to be connected to a source of electrical power, means to vary the voltage within the power supply unit, and output means for connecting suit able electrical apparatus to the power supply unit.
  • the apparatus of this invention comprises a monitoring control for opening and closing at least one side of the incoming line of the power supply unit.
  • the control of this invention comprises a key operated tumbler lock 38 mounted to the front panel 14.
  • the tumbler lock includes a key plug 40 (FIG. I) rotatable in a lock cylinder 42 with a keyway 44 accessible from an exterior surface of the power supply unit.
  • the external cylindrical surface of the lock cylinder 42 may be threaded as at 43 inorder to receive a pair of lock nuts 46, 46' to firmly clamp the tumbler lock 38 to the front panel 14.
  • a bracket 48 is clamped to the internal wall of front panel 14 by means of the internal lock nut 46.
  • Bracket 48 is generally U- shaped including a pair of legs having inturned edges 50 for the purpose of retaining a pair of circuit breaker elements 52, 54. Fasteners 57 are used to secure the circuit breaker elements to the inturned edges 50 of bracket 48.
  • Circuit breaker elements 52, 54 of FIG. 3 are multiterminal fully magnetic heavy duty industrial circuit breakers which serve as an on-off switch to open both the positive and negative sides of the incoming line of the power supply unit.
  • Circuit breaker elements 52, 54 are identical and include internal switching means (not shown) adapted to open in the event of an overloaded condition of the incoming line and external reset arms 56, 58 respectively adapted to reset the internal switching means to a closed position.
  • the circuit breaker elements 52, 54 of FIG. 3 are manufactured by Airpax Electronics, Inc. (Cambridge Division).
  • Airpax Electronics, Inc. Airpax Electronics, Inc. catalogue illustrating circuit breaker APL31-203-3.
  • the external reset arms 56, 58 are linked to the internal switching means of the respective circuit breaker elements 52, 54 such that after tripping of the internal switching means, the external reset arms 56, 58 may reset said internal switching means to a closed position.
  • a lost motion connection is provided between the external reset arms 56, '58 and the internal switching means such that the internal switching means may open independently of the external reset arms 56, 58.
  • the lost motion means within the circuit breaker elements permits the internal switching means to open independently of the external reset'arms.
  • Interconnecting the key plug 40* of the tumbler lock 38 and the external reset arms 56, 58 is a linkage comprising a connecting arm -60 nonrotatably secured to the key plug 40 and a pin 62 disposed within passageways defined within the external reset arms 56, '58.
  • a nut 64 and locking washer 66 may be disposed about a threaded end of the key plug 40' in order to firmly secure the connecting arm 60 thereto. It is thus to be understood that the connecting arm 60, nut 64 and lock washer 66 rotate with the key plug 40 disposed within lock cylinder 42. Rotation of the key plug 40 is accomplished as by inserting a suitable key within keyway 44 and thereafter rotating the key.
  • the circuit breaker elements 52, 54 are disposed generally normal to the axis of the key plug 40 such that the pin 62 is generally normal to the connecting arm 60 with one end of pin 62 disposed within a passageway 69 of the connecting arm 60.
  • Spacer elements 70 are disposed about pin 62.
  • a pair of clips 72 are positioned on the pin 62 at either end thereof in order to hold the pin in place.
  • passageway 69 within the connecting arm 60 is considerably larger than the cross section of the pin 62 and spacer element 70 in order to insure that the connecting arm may freely rotate without binding the pin 62 or the spacer elements 70.
  • the on-olf positions of the connecting arm 60' are shown in FIG. 5.
  • circuit breaker elements are inserted into the circuitry of the power supply unit as by connecting a respective terminal 73 (-FIG. 2) of each circuit breaker element to a respective side of the incoming line and by connecting a respective terminal 74 of each circuit breaker element to the load.
  • a third terminal 76 may be provided for shunt operation of the circuit breaker.
  • the internal switching means of the circuit breaker elements serves to open the line between terminal 73 and terminals 74, 76.
  • a pair of circuit breaker elements are installed in the power supply unit to open each side of the incoming line to the power supply unit, it should be understood that this invention is equally applicable to a single circuit breaker element connected in series with one side of the incoming line.
  • the indicating light 36 With power supplied to the output jacks, the indicating light 36 will be on. In the event that the power supply unit is later short circuited (due for instance to improper student use of laboratory equipment) the circuit breaker elements 52, 54 will open thereby disconnecting all power from both sides of the incoming line. With power thus interrupted, the indicator light 36 will go out. It should be pointed out at this time that the circuit breaker elements 52, 54 in opening will do so because the internal switching means of the circuit breaker elements have opened independently of the external reset arms 56, 58. As is characteristic of standard tumbler locks, the plug 40 of the lock may not be rotated with the key removed. The lost motion connection between the internal switching means of the circuit breaker elements and the ex ternal reset arms permits the internal switching means to open in spite of the fact that the external reset arms are locked in place by the nonrotating connecting arm 60 (with the key 68 removed).
  • circuit breaker It is contemplated that advanced laboratory students may be permitted to retain a key to their power supply unit since they will be permitted to reactivate the unit themselves in the event of inadvertent overloading of the circuit. Key operation of the circuit breaker also prevents access to the power supply unit by unauthorized personnel. With the circuit breaker in the open or oil position and the key removed, the student may be assured that his work will not be disturbed by unauthorized personnel.
  • This invention is also directed to a method of sensing and correcting an overloaded circuit including a power supply unit with an incoming line adapted to be connected to a source of electrical power, means within the power supply unit to vary the voltage, and output means for connecting electrical apparatus to the power supply unit.
  • the method steps of this invention include the steps of:
  • circuit breakers of the same general type can be used in conjunction with a tumbler lock within the spirit of this invention.
  • the circuit breaker described is particularly well suited to this invention as it may be readily mounted to the support bracket 48 and fastened to the front panel 14 of the power supply unit.
  • the circuit breaker described is particularly well suited to this invention as it includes an internal lost motion tripping feature. This permits the internal switching means to open even with the external reset arm held in the on position as removal of the key from the keyway serves to lock the external reset arm in the on position.
  • the lost motion connection between the internal switching means and the external reset arm permits the internal switching means to open in the event of an overloaded condition of the circuit without requiring movement of the external reset arm or the key plug.
  • Other circuit breakers of this general type can be used with this invention.
  • the lost motion linkage between the key plug and the internal switching means is located within the circuit breaker between the external reset arm and the internal switching means.
  • the key plug of the tumbler lock is capable of rotating in one direction with the key removed.
  • the indicator light 36 of the front panel 14 has been described as normally illuminated to indicate power at the various outlets at the power supply unit.
  • the method of this invention should be considered other structures for sensing the opening of the internal switching means of the circuit breaker elements such as an audio alarm, a meter, or other signaling devices well known to those skilled in the art.
  • an electrical power supply unit comprising an incoming line having a positive and negative side adapted to be connected to a source of electrical power, means to vary the voltage, and output means for connecting electrical apparatus to the power supply unit; a monitoring 8 control for opening and closing at least one side of the incoming line, said control comprising:
  • a key operated tumbler lock including a key plug rotatable in a lock cylinder with a keyway accessible from an exterior surface of the power supply unit;
  • circuit breaker connected in series with at least one side of said incoming line and having internal switching means adapted to open in the event of an overloaded condition of said incoming line and further including an external reset arm adapted to reset said internal switching means to a closed position;
  • linkage means interconnecting said key plug and said external reset arm whereby said internal switching means may be reset by said key
  • lost motion means to permit said internal switching means to open independently of said key plug.
  • said lost motion means is defined as a lost motion connection between said internal switching means and said external reset arm.
  • linkage means is defined as a radial connecting arm secured to said key plug and a pin secured to said external reset arm with a connecting means between said connecting arm and said pin.
  • said connecting means is defined as a slot in said connecting arm with an end of said pin disposed within said slot.
  • a method of protecting against damage to electrical equipment caused by an overloaded circuit which circuit includes an electrical power supply unit which includes an incoming line having a positive and negative side adapted to be connected to a source of electrical power, means to vary the voltage, output means for connecting electrical apparatus to the power supply unit, a circuit breaker connected in series with at least one side of the incoming line and having internal switching means adapted to open in the event of an overloaded condition of the incoming line and further including an external reset arm adapted to reset the internal switching means to a closed position, a key operated tumbler lock including a key plug rotatable in a lock cylinder with a keyway accessible from the exterior of the power supply unit, a mechanical linkage between the key plug and the external reset arm, a lost motion linkage between the internal switching means and the key plug permitting the internal switching means to open independently of the key plug, and an electrical apparatus connected to the power supply 50 unit output means, comprising the steps of:

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  • Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)
US703167A 1968-02-05 1968-02-05 Method and apparatus for sensing and correcting an overloaded electrical circuit Expired - Lifetime US3543096A (en)

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US70316768A 1968-02-05 1968-02-05

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US (1) US3543096A (enrdf_load_stackoverflow)
DE (1) DE1905518A1 (enrdf_load_stackoverflow)
GB (1) GB1259343A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3695287A (en) * 1970-11-27 1972-10-03 Richard T Reese Thief proof fuel system
US6757589B1 (en) 1999-09-21 2004-06-29 Phil A. Parker Service panel with utility controller
US20080224835A1 (en) * 2007-03-16 2008-09-18 Leviton Manufacturing Company, Inc. Tamper resistant switch combination device
US20110178609A1 (en) * 2010-01-18 2011-07-21 Parker Phil A Service panel with microprocessor
US9683911B2 (en) 2010-01-18 2017-06-20 Wcm Industries, Inc. Service panel with microprocessor
US11815195B1 (en) 2019-08-12 2023-11-14 Wcm Industries, Inc. Water and gas utility control systems and retrofitting kit
US12411466B2 (en) 2023-07-20 2025-09-09 Wcm Industries, Inc. Service panel with microprocessor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3325746C1 (de) * 1983-07-16 1985-04-11 Bochumer Eisenhütte Heintzmann GmbH & Co KG, 4630 Bochum Stempel für Ausbaugestelle
DE3521153A1 (de) * 1985-06-13 1986-12-18 Brown, Boveri & Cie Ag, 6800 Mannheim Selbstschalter

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3247337A (en) * 1963-07-01 1966-04-19 Louis A Wiegel Combined meter and circuit breaker assembly

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3247337A (en) * 1963-07-01 1966-04-19 Louis A Wiegel Combined meter and circuit breaker assembly

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3695287A (en) * 1970-11-27 1972-10-03 Richard T Reese Thief proof fuel system
US6757589B1 (en) 1999-09-21 2004-06-29 Phil A. Parker Service panel with utility controller
US20080224835A1 (en) * 2007-03-16 2008-09-18 Leviton Manufacturing Company, Inc. Tamper resistant switch combination device
US20110178609A1 (en) * 2010-01-18 2011-07-21 Parker Phil A Service panel with microprocessor
US8543225B2 (en) 2010-01-18 2013-09-24 Phil A. Parker Service panel with microprocessor
US9683911B2 (en) 2010-01-18 2017-06-20 Wcm Industries, Inc. Service panel with microprocessor
US10162321B1 (en) 2010-01-18 2018-12-25 Wcm Industries, Inc. Service panel with microprocessor
US10168680B1 (en) 2010-01-18 2019-01-01 Wcm Industries, Inc. Service panel with microprocessor
US10509380B1 (en) 2010-01-18 2019-12-17 Wcm Industries, Inc. Service panel with microsprocessor
US11269301B1 (en) 2010-01-18 2022-03-08 Wcm Industries, Inc. Service panel with microprocessor
US11747777B2 (en) 2010-01-18 2023-09-05 WCM Industries, Inc Service panel with microprocessor
US11815195B1 (en) 2019-08-12 2023-11-14 Wcm Industries, Inc. Water and gas utility control systems and retrofitting kit
US12411466B2 (en) 2023-07-20 2025-09-09 Wcm Industries, Inc. Service panel with microprocessor

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Publication number Publication date
DE1905518A1 (de) 1969-11-13
GB1259343A (enrdf_load_stackoverflow) 1972-01-05

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