Browse Prior Art Database

Ground Loop Locator

IP.com Disclosure Number: IPCOM000073527D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Bunch, AD: AUTHOR [+3]

Abstract

Often when electrical equipment frames are assembled and internal panel wiring has been installed, unintentional short circuits occur. These shorts are predominantly between DC ground and the unit frame. It is desirable to locate the position of the short quickly and accurately so that a repair can be made.

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Ground Loop Locator

Often when electrical equipment frames are assembled and internal panel wiring has been installed, unintentional short circuits occur. These shorts are predominantly between DC ground and the unit frame. It is desirable to locate the position of the short quickly and accurately so that a repair can be made.

High frequency (approximately 100 KHZ) impedance measuring equipment can be utilized to measure between various points A and B on a system with a so-called ground loop, point A being applied to signal ground and point B being applied to frame ground. The test is continued in a systematic way until the lowest impedance reading between points A and B is obtained. The physical short location is close to that point.

Equipment for this purpose includes a 100 KHZ Oscillator which supplies a test signal to points A and B through a buffer amplifier. The short circuit between A and B in the equipment being tested acts as a shunt between these two points, so that the voltage between them is a function of the short circuit path between them. This AC voltage is amplified and peak detected and filtered to give a DC output at the voltmeter which is proportional to the impedance of the "short" at the measuring point.

The use of a relatively high frequency test signal, together with attention to proper isolation between the input and output circuits, provides the sensitive test conditions necessary in view of the presence of massive frame parts, extensive ...