| Title |
Experimental Study of The Floating-Phenomenon on Neutral Ungrounded UPS System |
| DOI |
http://dx.doi.org/10.5207/JIEIE.2011.25.5.067 |
| Keywords |
Neutral Floating-Phenomenon ; Phantom Voltage ; Transient Overvoltage |
| Abstract |
In this study we investigate the background of UPS output transformer(△-Y) operation on neutral ungrounded system, and perform field experiment of neutral floating-phenomenon for the inter-locked securing of electric facilities and improvement of neutral floating-phenomenon. Experiment results show that a floating-phenomenon occurs when four-pole input-breaker trip and the neutral to earth voltage occurring concurrently is identified as phantom voltage. And the measures for the transient overvoltage that can occur in floating-state also are investigated. As a result, the risk elements of neutral ungrounded method as well as neutral floating-phenomenon are removed by installation of separate solidly-grounded transformer and switching four-pole input-breaker to three-pole input breaker. |