GB1461480A - Safety circuit and apparatus incorporating it - Google Patents

Safety circuit and apparatus incorporating it

Info

Publication number
GB1461480A
GB1461480A GB1312974A GB1312974A GB1461480A GB 1461480 A GB1461480 A GB 1461480A GB 1312974 A GB1312974 A GB 1312974A GB 1312974 A GB1312974 A GB 1312974A GB 1461480 A GB1461480 A GB 1461480A
Authority
GB
United Kingdom
Prior art keywords
spray gun
control circuit
transistor
scr
voltage
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
Application number
GB1312974A
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.)
Graco Inc
Original Assignee
Graco Inc
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 Graco Inc filed Critical Graco Inc
Publication of GB1461480A publication Critical patent/GB1461480A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/003—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electrostatic apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/08—Plant for applying liquids or other fluent materials to objects
    • B05B5/10—Arrangements for supplying power, e.g. charging power

Abstract

1461480 Protective systems GRACO Inc 25 March 1974 [26 March 1973] 13129/74 Heading H2K An electrostatic spray gun protective circuit comprises a resistor connected in series with the spray gun electrode for developing a voltage proportional to the current through the electrode, a control circuit having an input connected to the resistor and an output connected to the high voltage source for the spray gun and which generates a signal when the voltage at its input exceeds a threshold level indicating overload, which signal causes the high voltage source to be switched off, and a time delay circuit and desensitizing means connected to the control circuit to cause the control circuit to respond to the voltage exceeding the threshold level only after a certain time delay after switching on to prevent initial surges from causing the spray gun to be switched off. During the desensitized period the control circuit may be responsive at a different threshold level or switching off of the high voltage source may be prevented. The control circuit comprises transistors 35, 36 and 40 which are switched on when a trigger switch 7 on the spray gun is closed to repeatedly charge capacitor 41 through resistor 46 to cause unijunction transistor 43 to repeatedly fire and send a train of firing pulses to SCR 31 in the supply circuit, thus allowing current to flow to the spray gun. A resistor network 55, 56, 57, 58 is in series with the supply to the spray gun and when excessive current flows the voltage at point 54 on the network exceeds the threshold voltage of unijunction transistor 63 causing it to conduct and pass a positive signal to SCR 59 which causes SCR 60 to fire in turn and cut off transistor 40 which cuts off the train of pulses to SCR 31 and thus stops current flowing to the spray gun. On switching on the spray gun an RC timing circuit 49, 50, 51 desensitizes the control circuit by switching on transistor 48 for a timed period to short out resistances 55, 56 and 57. In a second embodiment, Fig. 5, not shown, a resistance in series with transistor 48 establishes a different overload setting during this timed period. In a further embodiment, Fig. 6, not shown, an additional voltage divider resistor network alters the response of the unijunction transistor 63.
GB1312974A 1973-03-26 1974-03-25 Safety circuit and apparatus incorporating it Expired GB1461480A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00344685A US3809955A (en) 1973-03-26 1973-03-26 Safety circuit for electrostatic spray gun

Publications (1)

Publication Number Publication Date
GB1461480A true GB1461480A (en) 1977-01-13

Family

ID=23351565

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1312974A Expired GB1461480A (en) 1973-03-26 1974-03-25 Safety circuit and apparatus incorporating it

Country Status (8)

Country Link
US (1) US3809955A (en)
JP (1) JPS572392B2 (en)
CA (1) CA1001713A (en)
CH (1) CH620375A5 (en)
DE (1) DE2414524C2 (en)
FR (1) FR2223873B1 (en)
GB (1) GB1461480A (en)
IT (1) IT1007651B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2133942A (en) * 1983-01-20 1984-08-01 Sharp Kk Protection for a photocopier corona device
GB2212679A (en) * 1987-11-16 1989-07-26 Lai Chin Fay Overcurrent circuit breaker with time delay

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2620164C2 (en) * 1976-05-07 1978-07-06 Ionit Anstalt Bernhard Berghaus, Vaduz Method and device for monitoring high-current glow discharges
DE3138645A1 (en) * 1981-09-29 1983-04-14 Dr.Ing.H.C. F. Porsche Ag, 7000 Stuttgart "ELECTRONIC OVERCURRENT PROTECTION DEVICE"
DE3300027A1 (en) * 1983-01-03 1984-07-05 Hermann Behr & Sohn Gmbh & Co, 7121 Ingersheim Plant for generating a high electrical voltage for paint spray booths
US4688644A (en) * 1986-04-14 1987-08-25 Graco Inc. Ignition and fire suppressor
DE3709510A1 (en) * 1987-03-23 1988-10-06 Behr Industrieanlagen METHOD FOR CONTROLLING THE OPERATION OF AN ELECTROSTATIC COATING SYSTEM
DE3709509A1 (en) * 1987-03-23 1988-10-06 Behr Industrieanlagen Monitoring system for an electrostatic coating plant
EP0626208B2 (en) * 1993-04-08 2004-09-29 Nordson Corporation Power supply for an electrostatic spray gun
US5978244A (en) 1997-10-16 1999-11-02 Illinois Tool Works, Inc. Programmable logic control system for a HVDC power supply
US6144570A (en) * 1997-10-16 2000-11-07 Illinois Tool Works Inc. Control system for a HVDC power supply
US20050136733A1 (en) * 2003-12-22 2005-06-23 Gorrell Brian E. Remote high voltage splitter block
DE102015215402A1 (en) * 2015-08-12 2017-02-16 Gema Switzerland Gmbh Control circuit for protection against spark discharge

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2509277A (en) * 1945-04-06 1950-05-30 Ransburg Electro Coating Corp Control of electrostatic fields
DE834263C (en) * 1951-06-29 1952-03-17 Gen Motors Corp Electrical discharge system and its application to spray painting
BE715685A (en) * 1967-07-06 1968-10-16
US3641971A (en) * 1967-09-01 1972-02-15 Arvid C Walberg Apparatus for preventing arcing in an electrostatic coating system
US3725738A (en) * 1968-12-17 1973-04-03 V Sokolsky Device for preventing a corona discharge from assuming the form of a spark discharge in electrostatic painting apparatus
US3544844A (en) * 1969-07-11 1970-12-01 Hipotronics Interlocked operation control and overload protective circuit system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2133942A (en) * 1983-01-20 1984-08-01 Sharp Kk Protection for a photocopier corona device
GB2212679A (en) * 1987-11-16 1989-07-26 Lai Chin Fay Overcurrent circuit breaker with time delay
GB2212679B (en) * 1987-11-16 1992-01-15 Lai Chin Fay Over current circuit breaker

Also Published As

Publication number Publication date
DE2414524C2 (en) 1984-11-29
IT1007651B (en) 1976-10-30
FR2223873A1 (en) 1974-10-25
JPS49128950A (en) 1974-12-10
JPS572392B2 (en) 1982-01-16
US3809955A (en) 1974-05-07
CH620375A5 (en) 1980-11-28
FR2223873B1 (en) 1981-05-29
CA1001713A (en) 1976-12-14
DE2414524A1 (en) 1974-10-10

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee