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SOLENOID DRIVER WITH RESISTANCE AND LOAD CURRENT CONFIRMATION TESTING LOAD

IP.com Disclosure Number: IPCOM000248503D
Publication Date: 2016-Dec-09
Document File: 4 page(s) / 183K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention relates generally to safety systems and in particular to a method of testing of solenoid valves for proper wiring and correct electrical loading when powered on or off. The valve coil is electrically isolated when not powered. A minimum permissible amount of test current is injected into the valve to sense if the resistance of the valve and wiring are within bounds to detect for either short circuits or open circuits. An analog board using the JAFFA ASIC along with appropriate terminals is used to merge the resistance and the current testing done on solenoid valves. The technical advantages of the proposed method are reduction of cost by eliminating external current sensors and analog modules and applicability to both normally off and for normally on valves.

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This is the abbreviated version, containing approximately 48% of the total text.

SOLENOID DRIVER WITH RESISTANCE AND LOAD CURRENT CONFIRMATION TESTING LOAD

BACKGROUND

The invention relates generally to electric solenoid valves and in particular to a method of testing solenoid valves for proper wiring and correct electrical loading when powered on or off. Solenoid valves are one among the most frequently used control elements. The valve is controlled by an electric current through a solenoid. Fire control systems use remote valves that are electrically controlled. These valves remain inoperative over a period of time and hence require a confidence check for correct wiring. Some existing systems use a dual pole relay. The dual pole relay connects both the high and low side of the valve coil to power and to provide a return path. The valve coil is electrically isolated when not powered. A minimum permissible amount of test current is injected into the valve to sense if the resistance of the valve and wiring are within bounds to detect for either short circuit or open circuit. Existing systems use a supply voltage of either 24 V or 125 V. The test current is altered based on the supply voltage. At present 24 V systems are used. The valves of these systems are either normally closed or normally open.

FIG. 1: Method for calculating electrical or valve faults using Universal Analog Board.

The concept for the sensing and control of the remote valve or electrical load is shown in FIG. 1. The load is powered via two switches, one for high side power connection and the other for low side power connections. The switches have an internal current sensing unit to protect against short circuits and other power faults. A sensing resistor connected across a programmable gain amplifier

PG A

PG A

and to the low switch allows for current sensing in the circuit. The programmable gain amplifier (PGA) allows for varying current resolution on the A/D channel driven by the PGA. A second PGA connected across the load senses the voltage at the load. Hence the present systems have a current sensing unit to sense the current in the circuit when the valve is actuated. These extra current sensors add significant cost to the system and also occupy significant amount of space.

BRIEF DESCRIPTION OF DRAWINGS

The invention discloses a method of testing solenoid valves for proper wiring and correct electrical loading:

FIG. 1 shows a method for calculating electrical or valve faults using an analog board.

FIG. 2 shows an analog board with JAFFA ASICS and terminals for solenoid testing.

FIG. 3 shows an analog board with solenoid testing terminal board.

DETAILED DESCRIPTION

The invention discloses a method for testing solenoids for proper wiring and correct electrical loading whether powered on or off. The concept for the sensing and control of the remote valve or electrical load is shown in FIG. 2. The invention merges the resistance and the current done on solenoid valves by using an analog board and a terminal board. The analog board uses the JAFFA ASIC as sh...