A green method for cable diagnostics coupled with selective cable restoration - re-use instead of replace

• Published in: IEEE PES T&D 2010 pp. 1 - 4
• Main Author: Chatterton, Wayne J
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.04.2010
• Subjects: cable restoration; Capacitance; capacitive sensor; Dielectric breakdown; Dimethyl Dibutoxy silane; green cable restoration; green cable testing; green chemistry; partial discharge; Partial discharges; Power cables; Switches; Switchgear; System testing; Transformers; Trees - insulation; underground cables; Underground power cables; water trees
• ISBN: 9781424465460; 142446546X
• ISSN: 2160-8555; 2160-8563
• DOI: 10.1109/TDC.2010.5484424

Online testing of cable systems allows the cable owner to get a check up of one's system at operating voltage while all current activity is normal. No switching operations and no outage time is incurred while this effective capacitance testing is done. The entire system is analyzed including the cable, switchgear and any attached transformers or terminations. The responsive capacitance sensor can detect partial discharge (PD) activity as well as numerous pre-discharge events such as the growth of water trees and defects in the cable or components. Systems are graded from Level One where the component is in excellent condition all the way to Level Five where the component is at the end of its economic life. The cable owner can then direct where to focus budgeted preventative maintenance dollars. Cables that are too far gone can be replaced. Excellent cables can be checked again in a few years and cables in the middle can be restored. Dimethyl Dibutoxy silane (DMDB) has been found to be an excellent fluid for the restoration of damaged underground electrical cables. The cable owner is facing increasing failure rates of older electrical power cables due to the phenomenon of "water treeing". Once water diffuses in to the insulation and in the presence of an electrical field micro voids start to form that contain dissolved water. The presence of these micro voids causes the dielectric strength of the cable to deteriorate which ultimately leads to cable failure. If the cable is not too far gone the DMDB fluid can be injected into the cable from the terminations in switch gear or at transformers. The fluid diffuses into the cable and desiccates the micro voids filled with water. This fills the voids with the DMDB oligomers and removes water, causing the dielectric strength of the cable to rise quickly. The injected cable now has had its life extended by more than 20 years. Utilizing injection avoids the high cost associated with traditional cable replacement. Additionally, the energy required to both mine, and manufacture either aluminum or copper conductors utilized in new cables are no longer required. This has an enormous savings to the environment, "re-use versus replace". All alkoxysilanes produce an alcohol during their hydrolysis reaction. This new generation fluid improves upon its predecessors by creating the environmentally benign butanol in very trace amounts as opposed to the methanol created by the earlier generation products.