Abstract: A system for electrostatic deposition of a coating on an article from a charging device includes a direct current high voltage supply having first and second terminals across which the high voltage is impressed. The article to be coated is held at a potential substantially equal to the potential on one of the high voltage terminals. The article is suspended for relatively free movement toward and away from the device. The system includes a high-speed switch coupled between the high voltage terminals and a control circuit for controlling the switch. A sensing resistor in the high voltage output circuit monitors the current between the high voltage terminals. The control circuit includes a slope-detecting or fixed difference circuit responsive to the sensed current to detect too-rapid changes therein, such changes being indicative of close proximity of the article to the charging device and the possibility of high voltage arcing therebetween.

Abstract: A hammer protection circuit automatically disconnects a power supply from a hammer actuating coil in order to inhibit current flow through the coil when such current flow is either greater than a predetermined level or present for greater than a predetermined time period. The circuit comprises charging means coupled to the coil for charging up to a voltage level proportional to the level and duration of the current flow through the coil, comparator means coupled to the charging means for comparing the voltage level with a reference voltage and for generating an output signal when the voltage level bears a predetermined relationship toward the reference voltage, and means coupled to the comparator means and to the power supply and responsive to the output signal for disconnecting the power supply from the coil.

Abstract: Electrical loads connected to d-c supplies are protected from damage by overcurrent in the case of a load fault by connecting in series with the load a saturating transformer that detects a load fault and limits the fault current to a safe level for a period long enough to correct the fault or else disconnect the power supply.