To overcome the problem that it is cumbersome to detect an incorrect connection if a plurality of UPSs are connected in parallel.
The first and second UPS 6, 10 are provided with first and second UPS incorrect connection detecting circuits 25, 26. The first and second UPS incorrect connection detecting circuits 25, 26 are provided with: AC input detecting means for detecting voltages of R-phase input connecting conductors 7R, 11R; pulse generating circuits for detecting zero crossing of an AC input detection signal, and generating a pulse at this time; and pulse detecting circuits. The pulse detecting circuits are connected to the pulse generating circuit in the first incorrect connection detecting circuit 25, also connected to the pulse generating circuit in the second UPS incorrect connection detecting circuit 26 through a common connection conductor 29, and detect output pulses from both pulse generating circuits. An incorrect connection determining means is provided so as to determine the existence of the incorrect connection, based on the number of the pulses detected by the pulse detecting circuits.
HIRANO HIROYUKI
NAGAMATSU FUMIO
IYAMA OSAMU
| JPH09229977A | 1997-09-05 | |||
| JPH0451670A | 1992-02-20 | |||
| JPH03106838A | 1991-05-07 |
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