GB2344936A - Starter switch - Google Patents

Starter switch Download PDF

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Publication number
GB2344936A
GB2344936A GB9828097A GB9828097A GB2344936A GB 2344936 A GB2344936 A GB 2344936A GB 9828097 A GB9828097 A GB 9828097A GB 9828097 A GB9828097 A GB 9828097A GB 2344936 A GB2344936 A GB 2344936A
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GB
Grant status
Application
Patent type
Prior art keywords
switch
variable voltage
contact breaker
device
control device
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Withdrawn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
GB9828097A
Other versions
GB9828097D0 (en )
Inventor
Zia Shlaimoun
Original Assignee
Zia Shlaimoun
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

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/54Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere
    • H01H9/541Contacts shunted by semiconductor devices
    • H01H9/542Contacts shunted by static switch means
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/54Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere
    • H01H9/548Electromechanical and static switch connected in series
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/001Emergency protective circuit arrangements for limiting excess current or voltage without disconnection limiting speed of change of electric quantities, e.g. soft switching on or off

Abstract

A starter switch comprises first and second contact breaker switches, S1 and S2, and a variable voltage control device 9 connected across the second breaker switch S2, the arrangement enabling the first breaker switch S1 to be actuated to permit current to flow to the load via the variable voltage device and for the voltage at the load to be increased until there is substantially no potential difference across the variable voltage control device 9 at which time the second breaker switch S2 can be actuated to bypass the variable voltage device 9. The variable voltage device is preferably a thyristor.

Description

"Starter Switch" The present invention relates to starter switches. It relates particularly to starter switches for connection in the supply line for supply of current from a supply source to an electrical load such as an induction motor, and where contact breaker switches are used which might be subject to arcing damage.

Such starter switches can also be used for other operations such as electric arc furnaces or lighting applications where up to eight times the working current arises at start up. Such devices need to be"soft started", that is they require a voltage to be gradually or almost instantaneously increased from a very low voltage to a high voltage, and the invention is applicable to use in single or three phase A. C. supplies.

Generally starters are needed for induction motors, particularly heavy duty induction motors, because during start up very high currents will arise unless the supply voltage is constrained until full running speed is reached. Therefore the supply voltage will usually be gradually ramped up in a controlled fashion from a low level to a higher level as the motor reaches its full operating speed. In some applications start up may be much more rapid if high current is acceptable or a low power machine is to be started, nonetheless some form of current restriction is generally necessary.

It is also necessary to use contact breaker points which can be made or broken to ensure complete isolation from the supply for reasons of safety.

A problem however is that if there is high current flow from the supply to the load during start up, contact breaker switches when being made or broken will create arcing. This arcing in turn will cause pitting and general erosion of the contact breaker points. In time this results in contact breaker failure. Failure can result in the contact breaker being welded permanently on.

The present invention aims to overcome this problem.

Accordingly the invention provides a starter switch for connection in a supply line for supply of current from a supply source to an electrical load, for example an induction motor, comprising first and second contact breaker switches located in series within the supply line, and a variable voltage control device connected across the second contact breaker switch, the arrangement enabling the first contact breaker switch to be actuated in order to permit current to flow to the load via the variable voltage control device and for the voltage at the load to be increased until there is substantially no potential difference across the variable voltage control device at which time the second contact breaker switch can be actuated to by-pass the variable voltage device.

The device can be closed down by a reverse of the start up sequence. It will also be recognised that location of the first and second switches can be reversed and the system will operate the other way round.

A particularly useful form of the invention comprises a conducting busbar carrying the two switches, a contact breaker point for each switch being located at respective ends of the busbar and each co-operating with an adjacent contact breaker point.

Another possibility is to provide the variable voltage control device in parallel with a single switch (the second switch) as one component for connection in series with an existing switch (the first switch).

The arrangement in accordance with the invention enables the two contact breaker switches to be made during startup and broken during close-down without the risk of any significant sparking since each contact switch is made and broken in a state where virtually no current can flow since there is virtually no potential difference across each of the relevant switches at the relevant time. Not only does this reduce the wear on the contact breaker points, but also it enables machines to be started more rapidly without running into high current problems. It also means that the contact breaker points can be made from less costly materials.

Generally the variable voltage control device may be a solid state device which creates an impedance to current flow which is gradually reduced during start-up so as to enable the voltage to be ramped from a low voltage up to an operating voltage. A thyristor is a particularly useful form of semiconductor ramping device for use in the present invention.

An embodiment of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings in which: Figure 1 shows a view of the meghanical components of the device; Figure 2 is a schematic simplified circuit diagram ; Figure 3 is a perspective view of a unit housing the device of Figure 1 ; and Figure 4 shows a side view of an alternative arrangement in a housing.

Referring to Figure 1, a pair of contact breaker switches Sl and S2 are connected in series via a busbar 3 between a supply line 4 and a motor input lead 6. Each of the switches Sl and S2 is solenoid operated and incorporates a pair of breaker points which are brought together by energisation of the respective solenoid to make the switch and the converse to break the switch. A lead 8 connects the busbar 3 to a thyristor voltage ramping device 9 having an appropriate heat sink 10 and the output of the thyristor 9 is connected by a lead 11 to the input to the motor. This means, referring to Figure 2, that the supply line 4 is connected to the load via the switch Sl while the switch Sl is closed and the switch S2 is open and when the two switches are closed the supply line leads directly via those switches to the load.

The whole unit is housed within a casing as shown in Figure 3 which incorporates appropriate control buttons and indicator lights.

The arrangement in accordance with the invention therefore enables the switch Sl to be activated in order to permit current to flow to the load via the variable voltage control device and for the voltage at the load to be increased until there is substantially no potential difference across the variable voltage control device at which time the second switch can be activated to by-pass the thyristor variable voltage device. This means that at initial start up as Sl is closed there is virtually no current flowing through the contact breaker points of that switch and that when start up is complete there will be no voltage across switch S2 and therefore this switch can also be closed without any risk of arcing.

Close down occurs in the opposite way to start up in that switch S2 is opened when no voltage is developed across it; the thyristor 9 then ramps down the voltage until there is no voltage across Sl ; and the first switch Sl can then be opened with no risX of arcing.

Figure 4 then shows an alternative arrangement where the two switches are mounted separately rather than as a composite unit utilising a common busbar. As can be seen from the figure, the housing encloses a control card for controlling the sequence of operation of the switches in addition to the contactor switches Sl and S2, which, as before, will be electro-magnetically actuated.

Claims (5)

  1. CLAIMS 1 A starter switch for connection in a supply line for supply of current from a supply source to an electrical load, for example an induction motor, comprising first and second contact breaker switches located in series within the supply line, and a variable voltage control device connected across the second contact breaker switch, the arrangement enabling the first contact breaker switch to be actuated in order to permit current to flow to the load via the variable voltage control device and for the voltage at the load to be increased until there is substantially no potential difference across the variable voltage control device at which time the second contact breaker switch can be actuated to bypass the variable voltage device.
  2. 2 A starter switch according to Claim 1 comprising a conducting busbar carrying the two switches, a contact breaker point for each switch being located at respective ends of the busbar and each co-operating with an adjacent contact breaker point.
  3. 3 A starter switch according to Claim 1 or Claim 2 in which the variable voltage control device is a solid state device which creates an impedance to current flow which is gradually reduced during startup so as to enable the voltage to be ramped from a low voltage up to an operating voltage.
  4. 4 A starter switch according to Claim 3 in which the semi-conductor ramping device is a thyristor.
  5. 5 A component for use in a starter switch according to any preceding claim comprising a variable voltage device and a switch in parallel therewith, for connection in series with an existing switch of a motor.
GB9828097A 1998-12-18 1998-12-18 Starter switch Withdrawn GB2344936A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9828097A GB2344936A (en) 1998-12-18 1998-12-18 Starter switch

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9828097A GB2344936A (en) 1998-12-18 1998-12-18 Starter switch

Publications (2)

Publication Number Publication Date
GB9828097D0 true GB9828097D0 (en) 1999-02-17
GB2344936A true true GB2344936A (en) 2000-06-21

Family

ID=10844625

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9828097A Withdrawn GB2344936A (en) 1998-12-18 1998-12-18 Starter switch

Country Status (1)

Country Link
GB (1) GB2344936A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005099080A1 (en) 2004-04-05 2005-10-20 Siemens Aktiengesellschaft Circuit device for operating a motor and corresponding method
FR2896346A1 (en) * 2006-01-17 2007-07-20 Diamecans Soc Par Actions Simp Circuit breaker assembly for vehicle`s storage battery, has movable contact unit displaced to close or open electric contact between terminals of assembly, and electronic circuit with microprocessor for managing displacement of contact unit
FR2896345A1 (en) * 2006-01-17 2007-07-20 Diamecans Soc Par Actions Simp A circuit breaker comprising subsidiary current cut-off means
FR2901057A1 (en) * 2006-05-11 2007-11-16 Diamecans Soc Par Actions Simp adapts fuse has to be connected to two battery packs and charging process of the two storage batteries
WO2008040859A1 (en) * 2006-10-05 2008-04-10 Diamecans Battery circuit-breaker comprising means for determining a current flowing through the input electric terminal thereof
WO2008071134A1 (en) * 2006-12-14 2008-06-19 Siemens Aktiengesellschaft Device for galvanic isolation of a semiconductor switch, electronic switching device and contact-making and isolating module

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0179982A2 (en) * 1984-10-31 1986-05-07 International Business Machines Corporation High power direct current switching circuit
GB2221794A (en) * 1988-08-12 1990-02-14 Ass Elect Ind Circuit breaker

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0179982A2 (en) * 1984-10-31 1986-05-07 International Business Machines Corporation High power direct current switching circuit
GB2221794A (en) * 1988-08-12 1990-02-14 Ass Elect Ind Circuit breaker

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005099080A1 (en) 2004-04-05 2005-10-20 Siemens Aktiengesellschaft Circuit device for operating a motor and corresponding method
FR2896346A1 (en) * 2006-01-17 2007-07-20 Diamecans Soc Par Actions Simp Circuit breaker assembly for vehicle`s storage battery, has movable contact unit displaced to close or open electric contact between terminals of assembly, and electronic circuit with microprocessor for managing displacement of contact unit
FR2896345A1 (en) * 2006-01-17 2007-07-20 Diamecans Soc Par Actions Simp A circuit breaker comprising subsidiary current cut-off means
WO2007083009A1 (en) * 2006-01-17 2007-07-26 Diamecans Circuit breaker comprsing subsidiary current-breaking means
FR2901057A1 (en) * 2006-05-11 2007-11-16 Diamecans Soc Par Actions Simp adapts fuse has to be connected to two battery packs and charging process of the two storage batteries
WO2007132078A1 (en) * 2006-05-11 2007-11-22 Diamecans Cutout switch designed to be connected to two storage batteries and method for charging said storage batteries
WO2008040859A1 (en) * 2006-10-05 2008-04-10 Diamecans Battery circuit-breaker comprising means for determining a current flowing through the input electric terminal thereof
FR2906941A1 (en) * 2006-10-05 2008-04-11 Diamecans Soc Par Actions Simp battery circuit breaker comprising current determination means passing through the electric terminal of input
WO2008071134A1 (en) * 2006-12-14 2008-06-19 Siemens Aktiengesellschaft Device for galvanic isolation of a semiconductor switch, electronic switching device and contact-making and isolating module

Also Published As

Publication number Publication date Type
GB9828097D0 (en) 1999-02-17 application

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)