Abstract: The invention relates to an RFI filter used for avoidance of mains retro-action in the form of radio noise. RFI filters are connected to frequency converters in order to reduce radio noise transmitted via conductors. These filters comprise large noise-decoupling capacitors which are connected to earth, and during start up of the frequency converter the capacitors cause leakage currents to earth. This gives rise to problems in those circumstances, where a circuit breaker is connected to a frequency converter and an RFI filter, because the leakage current is higher than the trigger current for the circuit breaker. The solution to this problem is to place a resistor in series with the noise-decoupling capacitor and parallel with the resistor to place a switch, which can be opened or closed with a control signal from a controller. The invention also concerns a method for activation of an RFI filter.

Abstract: The invention relates to an RFI filter used for avoidance of mains retro-action in the form of radio noise. RFI filters are connected to frequency converters in order to reduce radio noise transmitted via conductors. These filters comprise large noise-decoupling capacitors which are connected to earth, and during start up of the frequency converter the capacitors cause leakage currents to earth. This gives rise to problems in those circumstances, where a circuit breaker is connected to a frequency converter and an RFI filter, because the leakage current is higher than the trigger current for the circuit breaker. The solution to this problem is to place a resistor in series with the noise-decoupling capacitor and parallel with the resistor to place a switch, which can be opened or closed with a control signal from a controller. The invention also concerns a method for activation of an RFI filter.

Abstract: A method of making an aluminum hydroxide and melamine blend. The method comprises jet milling a quantity of coarse particle size melamine until a line particle size melamine is obtain which has a median particle size of from about 0.5 .mu.m to about 45 .mu.m, passing the fine particle size melamine through an air classifier and a cyclone separator, and admixing the fine particle size melamine with a quantity of surface treated aluminum hydroxide in a high speed mixer.

Abstract: The invention relates to an electrical control unit for controlling the speed of a pump motor of a pressurized fluid supply system having a tank. A pressure responsive switch unit connected to the tank has at least three switch positions corresponding to pressure levels in the tank. The switch unit outputs three different voltage levels to a transistor and circuitry responsive to the three voltage levels utilizes this input to control the speed of the pump motor. The circuitry includes an integration capacitor and the effects of charging and discharging the capacitor in accordance with the three voltage levels produced by the switch unit are utilized for controlling the pump motor.