Protective device for electrostatic sprayer equipment

• US 4,672,500 A
• Filed: 09/14/1984
• Issued: 06/09/1987
• Est. Priority Date: 09/14/1983
• Status: Expired due to Fees

• Current Assignee: Sames SA A Organization of France
• Original Assignee: Sames S.A. (EXEL Industries SA)
• Inventors: Burtin, Jean-Pierre, Tholome, Roger
• Primary Examiner(s): Envall, Jr., Roy N.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/650,537
• Time in Patent Office: 998 Days
• Field of Search: 361/42, 361/47-50, 361/87, 361/235, 361/93, 361/101, 361/227, 361/228, 323/276-278, 363/56
• US Class Current: 361/93.7
• CPC Class Codes: B05B 5/10 Arrangements for supplying power, e.g. charging power in discharge apparatus B05B5/053
• CPC Class Codes: H02H 7/003 for electrostatic apparatus

Abstract

Electrostatic spraying equipment having, in a working area likely to contain inflammable mixtures, at least a terminal part of a high-voltage generator with an electrode for charging a jet of material sprayed from a sprayer. At least one low-voltage line connects the terminal part of the generator to a remotely sited power supply equipped with cut-out device. A protective device designed to prevent repeated arcing in the working area as a result of deterioration of the low-voltage line comprises, in series with the line, a sensing device for sensing a current lower than a predetermined minimum current. A control device responsive to the sensing device are connected to the aforementioned cut-out device so as to operate them when a current in the line lower than the predetermined minimum is sensed.

Claims

1. Electrostatic sprayer equipment comprising:

(a) a high-voltage generator;

(b) a sprayer operatively connected to said high-voltage generator;

(c) an electrode for charging a jet of material from said sprayer;

(d) an electrical power supply for supplying power to said high-voltage generator, said electrical power supply being sited remotely from said high-voltage generator;

(e) cut-out means for cutting off power from said electrical power supply;

(f) at least one low-voltage line for connecting said high-voltage generator to said electrical power supply; and

(g) a protective device for operating said cut-out means when a lower than threshold current is sensed in said at least one low-voltage line.

2. The electrostatic sprayer equipment according to claim 1 wherein said protective device comprises:

(a) sensing means connected in series with said at least one low-voltage line for sensing current in said at least one low-voltage line; and

(b) control means connected to said cut-out means, said control means being responsive to said sensing means to operate said cut-out means to cut off power from said electrical power supply wherein said cut-out means is operated when said sensing means senses a current lower than said threshold current.

3. The electrostatic sprayer equipment according to claim 2 wherein said electrical power supply supplies a unidirectional electric current.

4. The electrostatic sprayer equipment according to claim 3 wherein said sensing means comprises:

(a) a threshold comparator having at least one input; and

(b) a resistor adapted to be connected in series with said at least one low-voltage line and to said at least one input of said threshold comparator.

5. The electrostatic sprayer equipment according to claim 2 further comprising short-circuiting means operated by said control means in response to detection of current less than said threshold current for shunting said at least one low-voltage line and effecting safe discharge of capacitance.

6. The electrostatic sprayer equipment according to claim 3 wherein said control means comprises a flip-flop having a disable input for disabling said flip-flop prior to starting or, during adjusting or shutting down the generator.

7. The electrostatic sprayer equipment according to claim 3 further comprising:

(a) means for grounding said electrode;

(b) a low-voltage control line connected to said means for grounding; and

(c) means connected to said low-voltage control line and said control means for detecting a minimum current.

8. Electrostatic sprayer equipment comprising:

(a) a sprayer for spraying material;

(b) a high-voltage generator operatively connected to said sprayer for charging the material sprayed by said sprayer;

(c) an electrical power supply adapted to supply power to said high-voltage generator;

(d) at least one low-voltage line connected between said high-voltage generator and said electrical power supply;

(e) first means for detecting current in said at least one low-voltage line; and

(f) safety means responsive to said first means for detecting to interrupt the flow of power from said electrical power supply to said high-voltage generator when said current in said at least one low-voltage line is lower than a predetermined threshold.

9. The electrostatic sprayer equipment according to claim 8 further comprising:

(a) an electrode for charging a jet of material from said sprayer;

(b) grounding means for selectively grounding said electrode;

(c) at least one low-voltage control line connected to said grounding means;

(d) second means for detecting current in said at least one low-voltage control line, and wherein said safety means is responsive to said second means for detecting to interrupt the flow of power to said at least one low-voltage control line and said at least one low-voltage when said current in said at least one low-voltage control line is lower than a predetermined threshold.

10. The electrostatic sprayer equipment according to claim 9 wherein said electrical power supply sits remotely from said high-voltage generator.

11. The electrostatic sprayer equipment according to claim 10 further comprising cut-out means operated by said safety means in response to detection of a current lower than said predetermined threshold for interrupting power from said high-voltage power supply, said cut-out means comprising at least one transistor.

12. The electrostatic sprayer equipment according to claim 11 further comprising short-circuiting means operated by said safety means in response to detection of current less than said threshold current for shunting said at least one low-voltage line and effecting safe discharge of capacitance.

13. The electrostatic sprayer equipment according to claim 13 wherein said safety means comprises a flip-flop having a disable input for disabling said flip-flop prior to starting or, during adjusting or shutting down the generator