Leakage and continuity tester
First Claim
1. A test unit for testing the ground continuity and leakage characteristics of an electrical unit under test having a ground circuit and a chassis comprising a housing, means mounted on said housing adapted to be connected to the ground circuit of the unit under test, means adapted to be connected to the chassis, ground continuity test circuit means connected to said chassis connection means including a power supply and a conductor connected to said chassis for supplying electrical current though said chassis to said ground circuit to establish an electrical potential signal across the impedance of said ground circuit, said continuity test circuit means including comparator circuit means including an input signal from said chassis connection means and a fixed input signal, a go-no go type ground output indicator circuit including digital output means to indicate the acceptable or defective condition of said ground circuit as determined by said comparator circuit, and leakage current test means including input circuit means connected to the leakage current circuit under test including dual comparator means for comparing positive and negative polarity leakage signals with a standard signal, said input circuit means including an operational amplifier connected as a precision rectifier to sense positive and negative polarity input signals, and go-no go leakage output indicator circuit including digital output means to indicate the acceptable or defective condition of said leakage circuit as determined by said dual comparator circuit.
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Accused Products
Abstract
A leakage and continuity test unit for checking the ground impedance and leakage current in a medical instrument to ensure that the medical instrument is properly grounded and does not conduct an excessive amount of leakage current through the chassis. The unit includes a test probe which is interconnected with the equipment under test, the unit including a continuity circuit having a comparator which compares a fixed voltage with a voltage representative of the impedance to ground of the equipment under test. The output of the comparator is fed to a flip flop circuit which, when an excessive amount of ground impedance exists, drives a warning lamp circuit. If the impedance is below certain set limits, the flip flop will drive a lamp which indicates that the ground of the equipment under test is proper. The unit also includes a leakage detector circuit which includes an upper and lower limit control circuit which establishes different standards for the equipment under test depending on whether the equipment is to be used in critical service or general service areas within the hospital. The leakage signal is fed through a precision rectifier which in turn feeds the signal to a dual input comparator which dual input comparator is capable of testing either a positive or negative signal. The output of the comparator is fed to a flip flop circuit which drives a set of lamps, one of which warns the user that an excess of leakage current exists and the other of which indicates to the user that the leakage current is within the limit set by the gain control circuit.
24 Citations
19 Claims
- 1. A test unit for testing the ground continuity and leakage characteristics of an electrical unit under test having a ground circuit and a chassis comprising a housing, means mounted on said housing adapted to be connected to the ground circuit of the unit under test, means adapted to be connected to the chassis, ground continuity test circuit means connected to said chassis connection means including a power supply and a conductor connected to said chassis for supplying electrical current though said chassis to said ground circuit to establish an electrical potential signal across the impedance of said ground circuit, said continuity test circuit means including comparator circuit means including an input signal from said chassis connection means and a fixed input signal, a go-no go type ground output indicator circuit including digital output means to indicate the acceptable or defective condition of said ground circuit as determined by said comparator circuit, and leakage current test means including input circuit means connected to the leakage current circuit under test including dual comparator means for comparing positive and negative polarity leakage signals with a standard signal, said input circuit means including an operational amplifier connected as a precision rectifier to sense positive and negative polarity input signals, and go-no go leakage output indicator circuit including digital output means to indicate the acceptable or defective condition of said leakage circuit as determined by said dual comparator circuit.
Specification