Abstract: A powder spray coating discharge assembly (230, 260, 216, 228, 232) for connection to an electrostatic spray coating gun (210), the gun (210) having a gun body (212), means for connecting to a supply of coating powder and means for supplying a voltage (20) at first and second potentials respectively to first (292) and second electrical connections (294) each for connection to a respective one of a discharge electrode (232) and a counter electrode (260), the means for supplying the voltage (20) comprising: a variable voltage power supply (114) having an input connected to an electrical power source (110), an output connected to each of the first and second electrical connections (292, 294), a control circuit (128) for controlling the variable voltage power supply (20) and means (120) for sensing an output load, wherein the control circuit (128) is adapted to adjust the variable voltage power supply (20) to reduce the voltage and current in proportion to a sensed increase in load, or vice-versa.

Abstract: A powder transport method for transporting powder constantly and smoothly by a device comprising a transfer chamber into which a supply line and a discharge line open; a piston for generating negative pressure; a compressed gas passage through which compressed gas is injected into the transfer chamber; and a compressed gas control means, the method comprises: the discharge line is being closed when the piston reaches top dead center; then the supply line is closed; after a first predetermined time, compressed gas is injected into the transfer chamber in a manner that the total amounts of compressed gas injected are the same, then the discharge line is opened; after a second predetermined time, the piston starts its downward stroke; at the first predetermined time before the piston reaches bottom dead center, the injection of compressed gas is ceased; and the discharge line is closed and the supply line is opened.

Abstract: A powder spray coating discharge assembly (230, 260, 216, 228, 232) for connection to an electrostatic spray coating gun (210), the gun (210) having a gun body (212), means for connecting to a supply of coating powder and means for supplying a voltage (20) at first and second potentials respectively to first (292) and second electrical connections (294) each for connection to a respective one of a discharge electrode (232) and a counter electrode (260), the means for supplying the voltage (20) comprising: a variable voltage power supply (114) having an input connected to an electrical power source (110), an output connected to each of the first and second electrical connections (292, 294), a control circuit (128) for controlling the variable voltage power supply (20) and means (120) for sensing an output load, wherein the control circuit (128) is adapted to adjust the variable voltage power supply (20) to reduce the voltage and current in proportion to a sensed increase in load, or vice-versa.