An improved power supply for an electrostatic spray gun device having a voltage multiplier circuit adjusts to variations in the output load conditions of the multiplier circuit and dynamically modifies the operational loadline of the multiplier circuit in order to maintain optimal operating conditions for the spray gun device notwithstanding output load variations. The power supply utilizes a loadline manipulation circuit coupled to a feedback circuit that monitors the output load, and the manipulation circuit, in response to a feedback signal from the feedback circuit that is proportional to the output load, varies the input voltage level to the multiplier circuit to modify the loadline of the power supply in response to varying load conditions. The manipulator means of the power supply has memory means to store a variety of external commands which will control the manipulation means and a user interface to enter the external commands into the memory. The power supply also comprises a voltage limiting circuit coupled to the output of the multiplier circuit which regulates the output voltage level of the multiplier circuit so that when the output load current increases above a predetermined maximum level the output voltage is reduced to reduce the high voltage stress on the multiplier circuit and high voltage circuitry and reduce the amount of insulation that must surround the multiplier circuit and high voltage circuitry of the power supply in order to insulate it from ground potential.
RELATED APPLICATIONS
This application is a continuation of application Ser. No. 08/054,423 entitled "Improved Spray Gun Device With Dynamic Loadline Manipulation Power Supply" filed Apr. 8, 1993 now abandoned which application is completely incorporated herein by reference.
A method and apparatus for providing power to an electrostatic device includes a monitor and control system that prevents inadvertent and damaging electrical arcing. When the electrostatic device is first energized, voltage is gradually increased and the flow of electrical current is closely monitored. In the event the device is too close to ground or a grounded object, current flow exceeds a predetermined threshold and power is disconnected from the electrostatic device. Later, as the device voltage is increased to operating voltage, electrical current delivered to the electrostatic device is monitored for excessive current and excessive rate of change. If either fault condition is detected, power supply voltage may be reduced or disconnected, depending upon the severity of the fault. A microprocessor control system is illustrated for implementing the invention, including hardware and various software algorithms that provide the requisite gathering of information, analysis and responsive actions.
The present invention provides an electrostatic painting device with a transmission frequency adjustment device for automatically adjusting a transmission frequency in such a manner that the consumed current flowing in a high voltage booster circuit does not exceed a prescribed value. The present electrostatic painting device comprises a high-voltage booster circuit 201 provided in an electrostatic spray gun 2 to rectify a high frequency low voltage and generate a DC high voltage for electrostatic painting, a high-frequency low-voltage generator 1 provided independently of the electrostatic spray gun to generate a high frequency low voltage, a low-voltage cable 3 for connecting the high-frequency low-voltage to the high-voltage booster circuit, a current sensor 111 for detecting a current value corresponding to the intrinsic consumed current at the high-voltage booster circuit, and a frequency controller 107 and 112 for adjusting a frequency of a high frequency low voltage in such a manner that a current value detected by the current sensor does not exceed a predetermined value.
An apparatus for use in electrostatically applying coating material to an object includes a nozzle which directs a flow of coating material toward the object. A power supply unit provides an electric field to electrostatically charge the coating material. Control circuitry is provided to monitor the operating efficiency of the power supply unit and to provide an output signal when there is an impending failure of the power supply unit. The control circuitry monitors the relationship between an input current to the power supply unit and an output current from the power supply unit. When the relationship between the input current to the power supply unit and the output current from the power supply unit is outside of a predetermined range, the control circuitry is effective to provide an output signal to notify an operator that there is an impending power supply unit failure.
A method and device for monitoring operation of a high voltage generator which converts an input voltage into an output voltage which is higher than the input voltage, by measuring at least one first physical quantity which is representative of the input voltage; deriving at least one parameter from the at least one measured first physical quantity; comparing the at least one parameter with a second measured physical quantity which is representative of the magnitude of the output voltage; and producing a response when a predetermined minimum differential exists between the at least one parameter and the second measured physical quantity.
A safety tripping system is controlled to prevent electrical arcing during use of high voltage apparatus, in particular an electrostatic coating product applicator. The safety tripping system is activated if at least one current parameter reaches a threshold. The threshold is varied as a function of the value of the high voltage in accordance with a predetermined law.
