Browse Prior Art Database

Open Capacitor Detector

IP.com Disclosure Number: IPCOM000045046D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Deskur, KJ: AUTHOR

Abstract

Presently, an open capacitor in a parallel string is not detectable. Only a loss of a significant number of the capacitors can be recognized by total capacity measurement. Even in this case, the open units are not detected and the procedure is to replace all of them, which results in a cumbersome and expensive procedure.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Open Capacitor Detector

Presently, an open capacitor in a parallel string is not detectable. Only a loss of a significant number of the capacitors can be recognized by total capacity measurement. Even in this case, the open units are not detected and the procedure is to replace all of them, which results in a cumbersome and expensive procedure.

Open capacitors can be detected by using a modified inductive current sensing probe of the type that detects steep rising current pulses in a conductor. As shown in Fig. 1, the probe is placed in the vicinity of the capacitor that is repeatedly charged and discharged. A metal shield on the probe tip prevents the actuation of the probe by a stray field.

The capacitors are charged from a low internal resistance constant-current source. This causes the flow of charging current with a high initial value. Then, the output of the power supply is shorted by a shorting device. This causes the discharge current to flow also with a high initial value, as shown in Fig. 2. The inductive probe is placed next to the capacitor. If the capacitor is operational, the probe detects the charging and the discharging current. If the capacitor is open, no current will flow and the probe will not respond. The charge/ discharge cycle is repeated at the rate of a few cycles per second. This allows the movement of the probe along the bank of capacitors to detect the open ones.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]...