WO1997001283A1 - Constant current apparatus - Google Patents
Constant current apparatus Download PDFInfo
- Publication number
- WO1997001283A1 WO1997001283A1 PCT/GB1996/001545 GB9601545W WO9701283A1 WO 1997001283 A1 WO1997001283 A1 WO 1997001283A1 GB 9601545 W GB9601545 W GB 9601545W WO 9701283 A1 WO9701283 A1 WO 9701283A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- current
- stunning
- animal
- high voltage
- circuit
- Prior art date
Links
Classifications
-
- A—HUMAN NECESSITIES
- A22—BUTCHERING; MEAT TREATMENT; PROCESSING POULTRY OR FISH
- A22B—SLAUGHTERING
- A22B3/00—Slaughtering or stunning
- A22B3/08—Slaughtering or stunning for poultry or fish, e.g. slaughtering pliers, slaughtering shears
- A22B3/086—Stunning devices specially adapted for poultry
-
- A—HUMAN NECESSITIES
- A22—BUTCHERING; MEAT TREATMENT; PROCESSING POULTRY OR FISH
- A22B—SLAUGHTERING
- A22B3/00—Slaughtering or stunning
- A22B3/06—Slaughtering or stunning by electric current
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05C—ELECTRIC CIRCUITS OR APPARATUS SPECIALLY DESIGNED FOR USE IN EQUIPMENT FOR KILLING, STUNNING, OR GUIDING LIVING BEINGS
- H05C1/00—Circuits or apparatus for generating electric shock effects
- H05C1/04—Circuits or apparatus for generating electric shock effects providing pulse voltages
Definitions
- This invention relates to a constant current apparatus for the supply and the control of an electric current applied to a variable load.
- the invention is particularly, but not exclusively, suitable for use in animal stunning and/or slaughtering equipment.
- Animals such as poultry and rabbits are stunned before slaughter for humane reasons as well as to ensure that the quality ofthe flesh is not reduced.
- Electrical stunning is widely employed in poultry slaughter and there are Regulations which closely define the stunning action in terms of current and time.
- An animal can be slaughtered rather than just stunned by using an electric current and the invention encompasses the control of such currents. Animals such as cattle and sheep can also be stunned or slaughtered by such a controlled electric current.
- poultry is slaughtered at a rate of some thousands per hour, the poultry being suspended head down from individual units on a conveyor for stunning before slaughter.
- the poultry suspended on the conveyor is carried to a water bath positioned so that the head ofthe suspended bird is submerged a short distance while being moved through the water bath by the continuing action ofthe conveyor.
- the immersing ofthe head in the water ofthe bath completes an electrical circuit from a source of electrical energy, through the suspension unit, the suspended bird, the water and then the return to the source.
- the source is arranged to supply the appropriate current to conform to the Regulations.
- Patent publication WO 93/07757 describes a feedback regulated constant current circuit. This circuit requires a current sensor for each current path and a circuit of some complexity. Also, because ofthe closed loop nature ofthe circuit (as a result ofthe feedback signal), instabilities have been encountered. This problem is even more acute when sinusoidal (AC) currents are used to stun birds. Altemating currents (AC) have been found to cause fibrillation and to stun/slaughter more effectively.
- a constant current apparatus for supplying a constant current through a variable load in a high voltage circuit
- a low voltage circuit having a low voltage controller
- said low voltage circuit provides a signal, indicative ofthe desired current to pass through the load, said signal is input to a Wilson mirror
- means for connecting the output ofthe Wilson mirror to the load in the high voltage circuit via a means for protecting the output of the Wilson mirror against over voltage, said Wilson mirror output thence being connected to the variable load, thereby ensuring that a substantially constant current passes through said variable load.
- an electrical current for a controller for animal stunning and/or slaughter having a low voltage circuit including means to set a chosen current value in said circuit, a high voltage circuit to provide current of at least a stunning level and a potential adequate to ensure said at least stunning current flows in an animal and any associated current carrying constraining means on connection in said circuit energised in operation, and means to link the low voltage circuit to the high voltage circuit to exert control of the high potential at least stunning current to a known relationship to the set chosen current value.
- the means to link the low voltage and high voltage circuit may be a current mirror.
- the controller may include means to shape a drive wave form for input to t he low voltage circuit.
- the controller may have a bipolar drive wave and bipolar high voltage supplies.
- the controller may include a common means to shape a drive wave form and a multiplicity of linked low and high voltage circuits for respective current flow together with voltage isolating means between the common means and the linked low and high voltage circuit to provide a multiposition stunning current arrangement for a poultry slaughter conveyor.
- the controller may be arranged in a portable unit as a stunning or slaughter device for an individual animal.
- a method of animal shinning and/or slaughter using electric current including providing a high voltage supply of stunning and/or slaughter current, arranging said supply in a series path with means for selective application of regulated current to an animal for stunning and/or slaughter and a solid state current regulating circuit portion having a control input, establishing a current determining circuit portion having a drive signal input and a current dete ⁇ nining output and applying said current determining output thereof to said control input and further providing a drive signal source for application to said input whereby the stunning and/or slaughter current value in said series path is regulated to a value set by said drive signal source and said current determining circuit portion.
- the input control current to the first bipolar transistor of the Wilson Mirror is mirrored by a second bipolar transistor to form the output current.
- the first and second high voltage field effect transistors act as a series pass regulator in the collector circuit of the second bipolar transistor fixing its collector voltage and thus optimising its inherent constant current characteristic.
- the output transistor ofthe Wilson mirror is protected from over voltage and secondary breakdown conditions over the full range of output loads, by this regulator action.
- the Wilson mirror is for use with high voltage supply, typically in excess of 200 V and in conditions where there is variable output load.
- Other applications ofthe controller may be in specialist welding, such as MIG and TIG welding telecommunications and control of Piezoelectric (PZT) devices.
- a series pass regulator is in the form of high voltage Field Effect
- Transistors arranged at the output ofthe Wilson mirror.
- other components exist which could be used to perform this purpose, for example a shunt arrangement.
- Automatic detection means may be provided in order to check whether an animal has been properly stunned/slaughtered. If the detection means reveals that the animal is still alive apparatus may be provided for alerting an operator of this. For example a food dye marker may be squirted onto the animal which has not been stunned/slaughtered so that it may be removed and humanely killed. This avoids unnecessary trauma being suffered by the animal.
- the detection means and apparatus for applying a food dye may be electronically controlled and synchronised.
- Figure 1 shows oscillator and wave-shaping circuit stages of a stunning current controller embodying the invention
- Figure 2 shows the current output stage for the controller of Figure 1 ,
- Figure 3 shows the power supply stages for the circuits of Figure 1 and 2
- Figure 4 and 5 show in elevation and plan a general view of parts ofthe stunning stage of a poultry slaughter conveyor equipped with an embodiment ofthe invention.
- FIG. 1 shows a first part ofthe controller circuit where a wave form is produced.
- Portion 10 of the circuit is a sine wave generator including an integrated circuit IC4 (type 8038) and associated resistors and capacitors to select the frequency and mark/space ratio of the generator output.
- Portion 11 is a buffer stage, using one unit of an integrated circuit ICI (type 358), which reduces the loading by subsequent circuit portions on the generator.
- the output of portion 12 is supplied to a squarer, portion 13, and a combiner portion 14, both of which portions employ units of an integrated circuit IC2 (type 358).
- the sine wave from portion 12 is formed into a square wave at the output of portion 13.
- the sine wave from portion 12 is also supplied to the input of portion 14 in which portion the square wave and sine wave are combined to form a wave shape in which the upper and lower sections are sinusoidal with effectively instantaneous transitions of significant
- the circuit described so far provides a wave form which is supplied to a driver stage, the key portions are referred to by reference numerals portions 15, 16 and 17 in the lower section of Figure 1 and then to a high voltage constant current stage as shown in Figures 2a and 2b.
- Portion 16 is a driver providing a bi-directional output to an isolating transformer splitter stage 17.
- the output ofthe transformer splitter 17 is connected as indicated by the references P12, P14, P16, P18 to the high voltage stage shown in Figure 2b.
- This stage consists of two similar portions 21 , 22 and an optional portion 23 (described later).
- Each portion 21 , 22 includes a current mirror Tl, T2 and T5, T6 respectively.
- Diodes Dl and D2 act to permit current flow in portion 21 on positive half cycles ofthe combined sine and square wave and in portion 22 on negative half cycles.
- the diodes Dl and D2 interact with the instantaneous zero crossing portions of the sine/square wave.
- the action of the current mirror is achieved by setting a current through device Tl or T5 respectively (device type BU508) with resistor Rl or R4.
- Variable resistors VRI, VR2 provide adjustment for device characteristic differences.
- the set current is "mirrored" by devices T2 or T6 (device type BU508) from the V of devices Tl, T5 respectively.
- the current flow through devices T2 and T6 is from respective positive and negative high voltage supplies 24 Pl and 26 Pl .
- the voltage limit for a device type BU508 is 700 volts but a higher voltage is needed to drive the stunning current.
- Devices T3, T4 and T7, T8 respectively permit the higher voltage to be used.
- Devices T3 and T7 are controlled by devices T4 and T8 respectively to drop excess voltage with two benefits. First the voltage across devices T2 and T6 is limited to a safe value. Second the variation of voltage across devices T2 and T6 is reduced, improving the current mirror action.
- the low voltage current drive in devices Tl and T5 is converted by the current mirror action to a high voltage current drive ofthe same current value. Thus as a constant current is always supplied, there is no need for any feedback loop
- the output at 22 Pl is a waveform corresponding to the sine/square waveform at the output of portion 14 with a constant current set by the current mirror and a voltage swing provided by the high voltages at 24 Pl and 26 Pl .
- Portion 24 provides positive and negative 15 volt supplies for the low voltage portions ofthe circuits in Figures 1 and 2 and is conventional in form.
- Portion 25 provides the high voltage supplies with a suitably low source impedance. As stunning currents are about 100 milliamps and several birds are to be stunned at a time a current of 500 milliamps to one ampere may be needed.
- the power supply 25 is to produce a +650 volt / - 650 volt output, i.e. direct current. However alternating current may also be used if the wave shaping circuit is supplied with the alternating current frequency.
- the capacitors C100-C111 all have a value of lOOO ⁇ F.
- Capacitors Cl 12 to Cl 19 all have capacitance of 470 ⁇ F. All capacitors are suitable for high voltage (e.g. 385V) applications.
- FIG. 1 shows a circuit of a modified Wilson mirror, which may also be used in other applications as described below.
- the output current is generated by T2, without T3 and T4 the high voltage supply would distribute between the load and T2. At lower resistance loads the majority ofthe voltage would appear across T2 reducing reliability (due to voltage stress and secondary breakdown effects).
- T4 allows current to pass through resistors R2 and R3, hence reducing the gate to source voltage of T3.
- FIGS. 4 and 5 show parts of a stunning section of a poultry slaughter conveyor and water bath more fully described in a co-pending patent application of even date entitled "An apparatus for passing an electrical current through poultry and the like".
- This conveyor is designed to have twelve distinct stunning current supplies via respective slip rings in unit 110 to twelve opposed contact element pairs (twenty four in total) (130) spaced around a circular disc (128).
- each distinct supply is connected to two contact elements on opposite sides of the disc.
- a bird suspension unit, 116 In use only one of these contact elements will be in contact with a bird suspension unit, 116, and preferably displaces the suspension unit against the load ofthe bird, as shown in Figure 4.
- a return path is provided from an electrode plate in the water bath, 113.
- the current mirror permits the current to be set to a required value which will be maintained without the use of current sensors and feedback, as has hitherto been the preferred arrangement. Furthermore in a feedback system the current value will take a certain time to reach the required value. This time can be as much as one or two seconds during which the current will go through a wide range of values as a rapid oscillation. Such time is a significant part of the stunning time and could affect the stunning action.
- the constant current controller now provided by the technique described above achieves the required value almost instantaneously and then has a steady condition. Clearly current values and duration and a high voltage supply value will be chosen appropriate to the animal and whether stunning or slaughter is required.
- the Regulations require a current of 105 milliamps and an immersion time of two to four seconds for chickens and this requirement can be met with the technique described above , despite variation of bird resistance and other variables.
- Values for the resistance of the path including the suspended bird can be from below 1000 ohms to above 3000 ohms, the actual bird being up to 1500 ohms, so at least 300 volts rms must be available from the high voltage supply, and more should be provided to allow for circuit resistance and impedance.
- the current controllers energise the contacts via the slip rings all the time and the timing and duration ofthe stunning current is controlled by the contact between the suspension units and the contact elements, so the speed of the line will affect the duration of current. If required the timing and duration of the current could be determined by portion 15 of Figure 1 being operated by a signal derived from the speed ofthe conveyor and the position ofthe contact disc, or other suitable means. This would overcome problems where variation of line speed adversely affects stunning conditions.
- a single channel constant current controller could be used for on-farm culling, providing the required constant current for the Regulations.
- the current cycles and thus current duration can be monitored using circuit portion 23 and data recorded using a personal computer.
- the duration monitor facility is appropriate for a single channel controller for on-farm culling. Details ofthe electronic circuits not given above will be readily apparent to those skilled in the art as will variations of devices used and the addition of spike suppression and like techniques, particularly in the high voltage regions ofthe controller.
- the current controller may be suitable for applications in other applications where there is a rapidly varying high voltage supply and wherein a constant current supply is required.
- Such applications may include telecommunication and broadcast systems, such as klystrons and magnetrons, electroplating systems, or any other electrically "noisy" or unstable environments in which a constant current is required.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Insects & Arthropods (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
- Housing For Livestock And Birds (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP9504246A JPH11508722A (en) | 1995-06-27 | 1996-06-27 | Constant current device |
EP96920992A EP0835059A1 (en) | 1995-06-27 | 1996-06-27 | Constant current apparatus |
MXPA/A/1997/008921A MXPA97008921A (en) | 1995-06-27 | 1997-11-19 | Current apparatus conti |
US08/998,279 US5954572A (en) | 1995-06-27 | 1997-12-24 | Constant current apparatus |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9513018.3 | 1995-06-27 | ||
GBGB9513018.3A GB9513018D0 (en) | 1995-06-27 | 1995-06-27 | Current controller |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/998,279 Continuation US5954572A (en) | 1995-06-27 | 1997-12-24 | Constant current apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997001283A1 true WO1997001283A1 (en) | 1997-01-16 |
Family
ID=10776705
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1996/001545 WO1997001283A1 (en) | 1995-06-27 | 1996-06-27 | Constant current apparatus |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0835059A1 (en) |
JP (1) | JPH11508722A (en) |
GB (1) | GB9513018D0 (en) |
WO (1) | WO1997001283A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2000032049A1 (en) | 1998-11-27 | 2000-06-08 | Btg International Limited | Electrical animal stun/kill apparatus |
NL2002318C2 (en) * | 2008-12-11 | 2010-06-14 | Meyn Food Proc Technology Bv | An apparatus for passing an electrical current through a bird. |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4532481A (en) * | 1983-06-14 | 1985-07-30 | Harris Corporation | High voltage current mirror |
EP0292071A1 (en) * | 1987-05-22 | 1988-11-23 | Philips Composants | Current mirror with a high output voltage |
EP0356570A1 (en) * | 1988-09-02 | 1990-03-07 | Siemens Aktiengesellschaft | Current mirror |
WO1993007757A1 (en) * | 1991-10-18 | 1993-04-29 | British Technology Group Limited | Stunning apparatus |
WO1993023876A1 (en) * | 1992-05-21 | 1993-11-25 | Robert Bosch Gmbh | Current mirror with at least one pnp transistor |
-
1995
- 1995-06-27 GB GBGB9513018.3A patent/GB9513018D0/en active Pending
-
1996
- 1996-06-27 EP EP96920992A patent/EP0835059A1/en not_active Withdrawn
- 1996-06-27 JP JP9504246A patent/JPH11508722A/en not_active Withdrawn
- 1996-06-27 WO PCT/GB1996/001545 patent/WO1997001283A1/en not_active Application Discontinuation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4532481A (en) * | 1983-06-14 | 1985-07-30 | Harris Corporation | High voltage current mirror |
EP0292071A1 (en) * | 1987-05-22 | 1988-11-23 | Philips Composants | Current mirror with a high output voltage |
EP0356570A1 (en) * | 1988-09-02 | 1990-03-07 | Siemens Aktiengesellschaft | Current mirror |
WO1993007757A1 (en) * | 1991-10-18 | 1993-04-29 | British Technology Group Limited | Stunning apparatus |
WO1993023876A1 (en) * | 1992-05-21 | 1993-11-25 | Robert Bosch Gmbh | Current mirror with at least one pnp transistor |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2000032049A1 (en) | 1998-11-27 | 2000-06-08 | Btg International Limited | Electrical animal stun/kill apparatus |
NL2002318C2 (en) * | 2008-12-11 | 2010-06-14 | Meyn Food Proc Technology Bv | An apparatus for passing an electrical current through a bird. |
Also Published As
Publication number | Publication date |
---|---|
JPH11508722A (en) | 1999-07-27 |
EP0835059A1 (en) | 1998-04-15 |
MX9708921A (en) | 1998-03-31 |
GB9513018D0 (en) | 1995-08-30 |
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