US3809955A - Safety circuit for electrostatic spray gun - Google Patents

Safety circuit for electrostatic spray gun Download PDF

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Publication number
US3809955A
US3809955A US00344685A US34468573A US3809955A US 3809955 A US3809955 A US 3809955A US 00344685 A US00344685 A US 00344685A US 34468573 A US34468573 A US 34468573A US 3809955 A US3809955 A US 3809955A
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United States
Prior art keywords
circuit
high voltage
switching device
current
output
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Expired - Lifetime
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US00344685A
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English (en)
Inventor
R Parson
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Graco Inc
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Graco Inc
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Publication date
Application filed by Graco Inc filed Critical Graco Inc
Priority to US00344685A priority Critical patent/US3809955A/en
Priority to FR7408734A priority patent/FR2223873B1/fr
Priority to CH373474A priority patent/CH620375A5/de
Priority to CA195,470A priority patent/CA1001713A/en
Priority to GB1312974A priority patent/GB1461480A/en
Priority to JP3316374A priority patent/JPS572392B2/ja
Priority to DE2414524A priority patent/DE2414524C2/de
Priority to IT20843/74A priority patent/IT1007651B/it
Application granted granted Critical
Publication of US3809955A publication Critical patent/US3809955A/en
Anticipated expiration legal-status Critical
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    • 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

Definitions

  • This invention relates to electrostatic coating systems and more particularly to a safety apparatus for safeguarding against excessive ionizing currents which otherwise could occur in the operation and use of electrostatic coating systems.
  • the invention is adaptable for use with either automatic electrostatic spray coating systems or with manual, hand-held electrostatic spray guns.
  • automatic spray coating systems the spray apparatus is fixedly mounted relative to a moving conveyor,.wherein articles to be sprayed are attached to the moving conveyor and moved past the spraying apparatus.
  • manual systems the spray gun is held in an operator's hand and manipulated so as to coat an article which is usually fixedly mounted.
  • the invention is particularly useful in this type of manual system.
  • electrical ionizing voltages approaching 100,000 volts between the spray gun electrode and the article to be coated.
  • the spray gun electrode is brought too close to the article the electrostatic ionizing current increases rapidly and the possibility exists for creating a dangerous electrostatic spark.
  • the present invention relates to a safety apparatus for sensing an increase in the electrostatic ionizing current and disabling the high voltage before an electrostatic spark is created.
  • the present invention seeks to improve over this and other prior art attempts at safeguarding against excessive ionizing currents while allowing for initial current surges required during system turn-on, by providing a single circuit which automatically monitors ionizing currents and disables the high voltage when a maximum threshold ionizing current is reached, but adjusts the relative ionizing current threshold to compensate for current surges during system turn-on.
  • the invention also provides improved electronic apparatus toaccomplish functions heretofore requiring electro-mechanical switching .devices.
  • This invention utilizes a resistance in series with a high voltage generating circuit for providing a voltage proportional to ionizing current.
  • a threshold switching device is connected to this resistance for providing a switched output responsive to a predetermined voltage level representative of an excessive ionizing current.
  • the threshold switching device is connected to a load cut-off device connected in a manner to remove the high voltage potential from the electrostatic spray gun electrode; and a desensitizing circuit is connected between the high voltage turn-on switch and the threshold switching device to provide an alternative threshold switching level during the period of initial turn-on of the electrostatic system.
  • This desensitizing circuit is adapted to cause the threshold switching device to react only to ionizing currents that are significantly higher than currents required to initially charge cable capacitance, and after initial cable charging is accomplished the desensitizing circuit causes the threshold switching device to revert to normal ionizing current responsiveness.
  • An additional object of this invention is to provide a safety apparatus having improved electronic. components and avoiding electromechanical devices.
  • a further object 'of this invention is to provide an electronic safety circuit for use with electrostatic spray coating systems wherein the level of safe ionizing current can be pre-selected and adjusted to enable the use of a circuit with a wide variety of electrostatic spray coating'system elements.
  • FIG. 1 is a pictorial representation of an electrostatic spray coating system
  • FIG. 2 is a block diagram of the principal electronic elements associated with said spray coating systems
  • FIG. 3 is a detail schematic diagram of one of the electronic elements of FIG. 2;
  • FIG. 4 is a detail schematic diagram of another of the 7 electronic elements of FIG. 2;
  • FIG. 5 is an alternative and preferred embodiment of the circuit of FIG-.4;
  • FIG. 6 is yet another embodiment of the circuit of FIG. 4.
  • FIG. 1 illustrates an electrostatic coating system.
  • An electrostatic spray gun 3 is connected by means of suitable hoses to an electrostatic powder'supply hopper 1.
  • the powder supply hopper 1 contains coating powder which is supplied under pressure to the spray gun 3 for application upon an article (not shown) to be coated.
  • Electrostatic spray gun 3 has an electrical connection to high voltage power supply and associated circuitry 2 by means of high voltage cable 4.
  • High voltage cable 3 I 4 may exist in a wide variety of lengths, typically rangingf'rom several feet up to 100 feet. Because of the length and electrical characteristics of high voltage cable 4, it has a considerable distributed capacitance which must be initially charged wheneverthe high voltage power supply is turned on.
  • a second cable 5 contains a wire connecting the trigger 7 of the electrostatic spray gun 3 to a control circuit within power supply 2 which will hereinafter be described.
  • Trigger 7 on spray-gun 3 controls the high v'oltage generating circuitry within power supply 2.
  • FIG. 2 illustrates a bloclcdiagram of the essential electronic elements relating to this invention.
  • Control circuit 10 is activatedby means of trigger cable 5 to energize high voltage power source 15.
  • Power source includes a transformer and rectifier circuit, so that a D.C.-voltage of magnitude SOKV-lOOKV is placed on high voltage cable 4 and coupled to a high voltage electrode (not shown) in electrostatic spray gun 3.
  • sensing circuit which 'is connected to high voltage transformer 15 by means of wire 19 and terminal 21.
  • Wire 19 is connected to one side of the rectified high voltage output circuit.
  • Sensing circuit 20 receives a control signal from control circuit 10 via line 9 and terminal 22, which control signal represents the initial turn-on state of the electrostatic high voltage.
  • Sensing circuit 20 also has an output terminal 23 which is connected to control circuit 10 via line 11; this output terminal conveys a signal representative of excessive ionizing current,and causes control circuit 10 to disable high voltage to the electrostatic spray gun.
  • Control circuit 10 is activated by trigger 7 on electrostatic spray gun'3, which is an electrical contact switch connecting a resistance 33 to ground iwhenthe trigger 7 is depressed. Since the other side of resistance 33 is connected to a positive voltagepower source, a current flows through resistance 33, causing transistor '35 to FIG. 3 illustrates in simplified schematic form the circuit details of control circuit 10 and power source 15.
  • the primary winding of high voltage transformer 16 is capacitively .connected to a saturable core inverter transformer 17. This saturable core inverter transformer is commonly used in the art for developing high voltages, and typically has a D.C. output voltage of approximately 400 volts.
  • the output voltage charges capacitor l8, and silicon-controlled rectifier(SCR) 31 is periodically fired to dump the capacitor charge into the primary winding'of high voltage transformer 16.
  • SCR 31 is tired upon application of a voltage pulse to its control element 32, in a manner known in the prior art.
  • This voltage is transformed and rectified via rectifier circuit 30 to create a high voltage of magnitude SOKV-lOOKV on high voltage cable 4, which is conveyed to the electrostatic spray gun electrode.
  • Rectifier circuit 30 may be any of a variety of commonly-known means for rectifying alternating currents, preferably of the voltage-doubler or t'ripler type.
  • the electrostatic high voltage potential exists between power source wire 19 and output cable 4..Wire 19 is connected to ground potential through a series resistance as will be described in connection with FIG.
  • the high voltage delivered to cable 4 is therefore generated by periodically applying a pulse to SCR 3 1 control element 32; removing these periodic pulses from control element 32 causes the high voltage to cease.
  • the signal which drives SCR control element 32 is generated by control circuit 10 of FIG. 3 as will now be described.
  • Lamp 38 is mounted on the control panel of high voltage power supply 2 and serves to indicate thecondition high voltage on;
  • lamp 38 is of a type which illuminates upon application of currents of the order of I00 milliamps.
  • transistor 36 When transistor 36 turns on and conducts current, it is
  • transistor 40 alsocauses transistor 40 to turn on.
  • the current conducted through transistor 40 is'of the order of less than several milliamps and, although drawn through lamp 39, is insufficient in magnitude to illuminate lamp 39.
  • transistor 35 When trigger 7 is released, transistor 35 ceases conduction and the voltage at line 9 and the base of transistor 36 proceeds in a negative-going direction. This causes transistor 36 to cut off, thereby cutting off current flow through la'mp '38, and also cutting off conduction of transistor 40.
  • transistor 40 cuts off, the oscillator circuit of unijunction transistor 42 also cuts off, and SCR firing pulses are no longer delivered to SCR control element 32.
  • control circuit 10 acts in response to trigger 7 to turn on high voltage on indicator lamp -38 and to repetitively fire SCR 3] to generate a high of the effects of sensing circuit 20.
  • the operation of control circuit in conjunction with sensing circuit will now be described, in particular with reference to FIGS. 3 and 4.
  • FIG. 4 illustrates sensing circuit 20, and will be described in terms of its interaction with control circuit 10 as illustrated in FIG. 3.
  • Line 9 connects the collector of transistor 35 to input terminal 22 of sensing circuit 20.
  • trigger 7 When trigger 7 is depressed, the voltage on line 9 goes positive, and this positive-going voltage is connected to the base of transistor 48 via input terminal 22 to cause transistor 48 to turn on and conduct current.
  • Transistor 48 remains conducting for a period of time determined by the RC time constant of resistors 49 and 50 and capacitor 51.
  • This turn-on time is variable and can be selected by adjusting resistor 50; resistor 50 is typically set to a value dictated by the electrical characteristics and length of high voltage cable 4, because the desired result is to cause transistor 48 to remain on for the length of time required to charge high voltage cable 4 to its ultimate electrostatic ionization potential.
  • transistor 48 After a suitable time interval, determined by the setting of resistor 50, transistor 48 ceases conduction and the voltage at junction point 54 returns to a potential determined by the relative values of resistances55-58 and the current into terminal 21.
  • resistance 58 is connected via terminal 21 and line 19 to one output from high voltage power source 15.
  • the currentpath can be traced from line 19 at the high voltage power source 15 output, through terminal 21, through resistors 58 and 55 in series, through resistors 56 and 57 in parallel, to ground illustrated in FIG. 4 as point 47.
  • the high voltage delivered to the spray gun electrode is of negative polarity.
  • the voltage at junction point 54 is proportional to this ionization current and is connected to the control element 62 of unijunction transistor 63to control the conductivity of the unijunction transistor 63. As the ionization current increases, the voltage at junction point 54 also increases; at some threshold potential unijunction transistor 63 conducts current, causing the voltage at terminal 23 to trigger positive. This threshold voltage point can be selected by adjusting resistor 57.
  • the positive-going voltage at terminal 23 is connected, via line 11, to SCR control element 59 which causes SCR 60 to fire and become conducting. When SCR 60 becomes conducting, current flows through lamp 39, causing it to illuminate. Lamp 39 is mounted on the high voltage power supply panel and is representative of the condition high voltage overload when illuminated.
  • the firing of SCR also causes transistor 40 to cut off, shutting off the oscillator action of unijunction transistor 43 and its associated circuitry. This, in turn, causes the voltage pulses at terminal 12 to cease, preventing further firing of SCR 31.
  • SCR 60 conducts current through lamp 39 and on transistor 36 to ground. SCR 60 will remain conducting for so long as transistor 36 is held in the on state, which is determined by trigger 7. If trigger 7 is released, transistor 35, and hence transistor 36, is cut off to break the conduction path through lamp 39, SCR 60, and transistor 36.
  • a pulse is generated by unijunction transistor 63 which causes the firing of SCR 60. This, in turn, illuminates h'igh-voltage-overload lamp 39 and disables the high voltage generating source 15. High voltage cannot again be generated until trigger 7 is released, causing a disruption of the series current path through transistor 36. Once trigger 7 has been released it can again be depressed to restart the high voltage generation as hereinbefore described.
  • FIG. 5 illustrates an improved variation of sensing circuit 20 wherein the circuit is responsive to excessive ionization currents even during the time interval required for electrostatically charging cable 4.
  • the circuit of FIG. 5 is similar to that of FIG. 4 in all respects except that a resistor has been connected between junction point 54 and the collector of transistor 48.
  • transistor 48 is gated on during a time interval approximately equal to the time required to charge the distributed capacitance of cable 4. During this time interval, the current will be higher than that required for normal operation because of the current needed for charging cable capacitance. Therefore, transistor 48 is used to shunt across resistors 55, 56 and 57 to effectively disconnect the ionization sensing circuit which would otherwise respond to this excessive ionization current to disable the high voltage.
  • resistor 65 in series with transistor 48 effectively acts as a desensitizing circuit rather than a disabling circuit.
  • resistor 65 With transistor 48 turned on, resistor 65 is connected in parallel with the resistor network comprised of resistors 55, 56 and 57. For a given ionization current level, this reduces the voltage at junction point 54 but does not clamp it to ground potential. Therefore, the sensing circuit comprised of unijunction transistor 63 and associated components is still responsive to excessive values of ionization currents and can still disable high voltage generation when excessive ionization currents are generated.
  • the current demand on high voltage source 15 may approach 200 microamps.
  • the ionization current levels for normal operation are of the order of 20-100 microamps.
  • the high voltage electrode on spray gun 3 is positioned close to a grounded source when trigger 7 is first depressed, the high voltage power source will be heavily overloaded and the circuit comprised of resistor 65 and transistor 48 in series will enable the sensing circuit to respond to this condition to disable further generation of high voltage.
  • FIG. 6 illustrates another embodiment of sensing circuit 20.
  • the sensing circuit has a desensitizing feature that provides for a cable-charging current that is some fixed multiple of the normal overload ionization current; the multiple is determined by the ratio of the sum of resistances 70 and 71 to 71 [(R70 R71 71].
  • the threshold switching value of unijunction transistor 63 is normally determined by the voltage at junction point 54, which is proportional to ionization current levels.
  • unijunction transistor 63 is operated at a reduced voltage because of the effect of the resistor divider formed by resistances 71 and 70.
  • Resistors 70 and 71 cause a reducedvoltage at junction point 75 and therefore make unijunction transistor 63 responsive to a reduced triggering voltage at, junction point 54.
  • resistances 58, 55, 56 and 57 are sized to accommodate the reduced threshold switching voltage requirements of unijunction transistor 63, so that threshold switching occurs at a predetermined ionization current level.
  • transistor 48 When spray gun trigger 7 is initially depressed, transistor 48 is caused to conduct as before to desensitize sensing circuit 20 for a time interval required for charging distributed cable capacitance. However, inthe operation of the circuit of FIG. 6, when transistor 48 becomes conductive, it applies the. full power supply voltage (+V) to junction point 75, thereby raising the threshold voltage sensitivity of unijunction. transistor 63. For example, if resistor 70 and 71 were chosen to normally provide a voltage at junction point 75 of +V/2, when transistor 48 is turned on the potential at junction point 75 suddenly becomes +V, raising the threshold voltage of unijunction transistor 63 by a factor of 2.
  • the circuit of FIG. 6 therefore provides for a cable charging surge current that is a fixed multiple of the normal ionization overload current.
  • a threshold switching device connected to said means for developing a first voltage, and adjustable to provide a switched output responsive to a preselected first voltage level
  • a load cutoff device connected to said high voltage and to said threshold switching device, and responsive to said switched output to remove the high voltage on said load;
  • a desensitizing circuit connected to said means for manually turning on said high voltage and to said means for developing a first voltage, said desensitizing circuit being activated for a predetermined time after manual turn-on of said high voltage to cause said threshold switching device to provide a switched output responsive to a different first voltage level.
  • said desensitizing circuit further comprises means for selecsensitizing circuit further comprises a resistance" switchable in parallel connection with at least a portion of said means for developing a first voltage.
  • said load cutoff device further comprises an oscillator circuit for delivering pulses at an output under normal conditions and wherein said pulses are stopped upon receipt of said threshold switching device switched output.
  • said load cutoff device further comprises a silicon-controlled rectifier (SCR) for receiving said pulses and for firing said SCR to cause generation of an alternating voltage, whereby the stopping of said pulses causes said SCR to stop firing.
  • SCR silicon-controlled rectifier
  • control circuit having an input connected to said current-sensing means and an output connected to said high voltage source, the control circuit generating a signal at its output in response to a presclected signal level at its input from said currentsensing means, said output signal causing deactivation of said high voltage power source;
  • a desensitizing circuit connected to said current sensing means and to said trigger to cause the control circuit output signal to be generated in response to a second and different control circuit input signal level, said desensitizing circuit becoming activated for a predetermined time interval after said trigger is engaged.
  • said desensitizing circuit further comprises a series-connected switching device and resistor coupled to said control circuit input, said switching device being closed in response to engaging said trigger.
  • Apparatus as claimed in claim 7 further comprising a resistance-capacitance circuit connected within said desensitizing circuit to cause said switching device to subsequently open upon-a predetermined accumulation of voltage charge on said capacitance.
  • said desensitizing circuit further comprises means for providing an offset voltage to, said control circuit input in an additive sense to said control circuit input signal level.
  • Apparatus as claimed in claim 8 further comprising a variable resistance in said resistance-capacitance circuit for selectively providing avariable time control over the subsequent opening of saidswitching device.
  • overload current sensing means for generating a signal proportional to high voltage supply current, said overload current-sensing means serially connected at said high voltage supply output;
  • a threshold switching device having an input connected to said overload current-sensing means and having an output connected to the high voltage power supply disabling circuit
  • a switching device having an output connected to said threshold switching device input and an input terminal, whereby at least a portion of said overload current sensing means is shunted by said switching device output;
  • a resistance-capacitance circuit connected between said switching device input terminal and said high voltage power supply switch to cause said switching device to become activated only during a time interval determined by the values of the resistance and capacitance.
  • said threshold switching device further comprises a unijunction semiconductor device having its control element at the switching device input and including a pulsegenerating circuit at its output, said pulse-generating circuit responsive to a predetermined input signal level.
  • a safety circuit for disabling a high voltage power supply output on the occurrence of either of two overload current conditions, the first overload condition occurring immediately after the power supply is switched on and the second overload condition subsequently occurring comprising:
  • overload current-sensing means for generating a signal proportional to high voltage supply current, said overload current-sensing means serially connected at said high voltage supply output;
  • a threshold switching device having an input connected to said overload current-sensing means and having outputs serially connected within a resistancedivider circuit
  • a switching device having an output connected at a second point in said resistance divider circuit to shunt at least a portion of the resistance in said resistance divider circuit, and having an input terminal;
  • a resistance-capacitance circuit connected between said switching device input terminal and said high voltage power supply switch to cause said switching device to become activated only during a time interval determined by the values of the resistance and capacitance.
  • Apparatus as claimed in claim 16 further comprising a shunt resistance between said second point in said resistance-divider circuit and circuit ground.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Nozzles (AREA)
  • Protection Of Static Devices (AREA)
  • Emergency Protection Circuit Devices (AREA)
US00344685A 1973-03-26 1973-03-26 Safety circuit for electrostatic spray gun Expired - Lifetime US3809955A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US00344685A US3809955A (en) 1973-03-26 1973-03-26 Safety circuit for electrostatic spray gun
FR7408734A FR2223873B1 (enrdf_load_stackoverflow) 1973-03-26 1974-03-14
CH373474A CH620375A5 (enrdf_load_stackoverflow) 1973-03-26 1974-03-18
CA195,470A CA1001713A (en) 1973-03-26 1974-03-20 Safety circuit for electrostatic spray gun
GB1312974A GB1461480A (en) 1973-03-26 1974-03-25 Safety circuit and apparatus incorporating it
JP3316374A JPS572392B2 (enrdf_load_stackoverflow) 1973-03-26 1974-03-26
DE2414524A DE2414524C2 (de) 1973-03-26 1974-03-26 Sicherheitsschaltung für Systeme zum elektrostatischen Beschichten
IT20843/74A IT1007651B (it) 1973-03-26 1974-04-08 Circuito di sicurezza sull alta tensione con caratteristiche di desensibilizzazione particolarmen te per impianti di struzzatura elettrostatica

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)

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US3809955A true US3809955A (en) 1974-05-07

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

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

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0075656A1 (de) * 1981-09-29 1983-04-06 Dr.Ing.h.c. F. Porsche Aktiengesellschaft Elektronische Überstromschutzvorrichtung
US4688644A (en) * 1986-04-14 1987-08-25 Graco Inc. Ignition and fire suppressor
US5566042A (en) * 1993-04-08 1996-10-15 Nordson Corporation Spray gun device with dynamic loadline manipulation power supply
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

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Publication number Priority date Publication date Assignee Title
DE2620164C2 (de) * 1976-05-07 1978-07-06 Ionit Anstalt Bernhard Berghaus, Vaduz Verfahren und Vorrichtung zur Überwachung von stromstarken Glimmentladungen
DE3300027A1 (de) * 1983-01-03 1984-07-05 Hermann Behr & Sohn Gmbh & Co, 7121 Ingersheim Anlage zum erzeugen elektrischer hochspannung fuer farbspritzkabinen
JPS59133570A (ja) * 1983-01-20 1984-07-31 Sharp Corp コロナ放電器の異常検出装置
DE3709509A1 (de) * 1987-03-23 1988-10-06 Behr Industrieanlagen Ueberwachungssystem fuer eine elektrostatische beschichtungsanlage
DE3709510A1 (de) * 1987-03-23 1988-10-06 Behr Industrieanlagen Verfahren zur betriebssteuerung einer elektrostatischen beschichtungsanlage
GB8726783D0 (en) * 1987-11-16 1987-12-23 Chin Fay Lai Over current circuit breaker
DE102015215402A1 (de) * 2015-08-12 2017-02-16 Gema Switzerland Gmbh Steuerschaltung zum Schutz gegen Funkenentladung

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Publication number Priority date Publication date Assignee Title
US2767359A (en) * 1951-06-29 1956-10-16 Gen Motors Corp High voltage current control
US3544844A (en) * 1969-07-11 1970-12-01 Hipotronics Interlocked operation control and overload protective circuit system
US3699388A (en) * 1967-07-06 1972-10-17 Ricoh Kk Apparatus for electrostatic charging of paper in electrophotographic reproduction
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

Family Cites Families (2)

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Publication number Priority date Publication date Assignee Title
US2509277A (en) * 1945-04-06 1950-05-30 Ransburg Electro Coating Corp Control of electrostatic fields
US3641971A (en) * 1967-09-01 1972-02-15 Arvid C Walberg Apparatus for preventing arcing in an electrostatic coating system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2767359A (en) * 1951-06-29 1956-10-16 Gen Motors Corp High voltage current control
US3699388A (en) * 1967-07-06 1972-10-17 Ricoh Kk Apparatus for electrostatic charging of paper in electrophotographic reproduction
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 (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0075656A1 (de) * 1981-09-29 1983-04-06 Dr.Ing.h.c. F. Porsche Aktiengesellschaft Elektronische Überstromschutzvorrichtung
US4688644A (en) * 1986-04-14 1987-08-25 Graco Inc. Ignition and fire suppressor
US5566042A (en) * 1993-04-08 1996-10-15 Nordson Corporation Spray gun device with dynamic loadline manipulation power supply
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
US6423142B1 (en) 1997-10-16 2002-07-23 Illinois Tool Works Inc. Power supply control system
US6562137B2 (en) 1997-10-16 2003-05-13 Illinois Tool Works Inc Power supply control system
US20050136733A1 (en) * 2003-12-22 2005-06-23 Gorrell Brian E. Remote high voltage splitter block

Also Published As

Publication number Publication date
GB1461480A (en) 1977-01-13
IT1007651B (it) 1976-10-30
CA1001713A (en) 1976-12-14
CH620375A5 (enrdf_load_stackoverflow) 1980-11-28
FR2223873A1 (enrdf_load_stackoverflow) 1974-10-25
DE2414524C2 (de) 1984-11-29
DE2414524A1 (de) 1974-10-10
JPS572392B2 (enrdf_load_stackoverflow) 1982-01-16
FR2223873B1 (enrdf_load_stackoverflow) 1981-05-29
JPS49128950A (enrdf_load_stackoverflow) 1974-12-10

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