Gema Switzerland Gmbh

Illinois Tool Works Inc.

Mario Vasella

Felix Mauchle

The invention relates to a control circuit for protecting an electrostatic spray-coating apparatus, which has a high-voltage supply, against spark discharge. The control circuit has a disconnection device for automatically disconnecting the high-voltage supply, and has a device for detecting abnormal operation of the high-voltage supply. The device for detecting abnormal operation of the high-voltage supply is designed to monitor at least one parameter which is characteristic of the operation of the high-voltage supply, and to output a corresponding disconnection signal to the disconnection device when the at least one parameter which is characteristic of the operation of the high-voltage supply exceeds or falls below a predefined or predefinable limit value.

Control circuit for protecting against spark discharge

An oscillator () for providing an oscillating voltage for a powder spray coating device () is specified. With the aim of improving operational safety, the oscillator () as claimed in the invention has a first signal generator () for generating an intermediate circuit voltage (), a second signal generator () for generating a modulation signal () and a modulation signal isolating element (), connected to the second signal generator (), while a first voltage monitoring device () is also provided, designed for continuously measuring the oscillator voltage (), comparing it with at least one specified or specifiable oscillator voltage reference value and, if a first comparison criterion is satisfied, outputting a modulation isolating signal () to the modulation signal isolating element ().

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Trubbach, Switzerland

Mario Vasella