| 摘要 |
<p>PROBLEM TO BE SOLVED: To inexpensively and precisely detect an error such as bulb life expiration of a plurality of illumination fixtures. SOLUTION: A required number of illumination fixtures are divided into a plurality of groups, when one further group is connected to a single phase power supply they are divided into two blocks with substantially identical number of lamps, and when connected to a three-phase power supply they are divided into three blocks of substantially identical number of lamps, a connection wire every one group is inserted through current detecting means 15 so that a current flowing each block is offset, and in the case of a single phase, a differential current of each block is detected, and in the case of three phases, an imbalance current of the three phases is detected. If a failure such as bulb life expiration occurs, a group or block in which a failure such as bulb life expiration occurs is arranged so as to be specified by detecting a differential current or an imbalance current. With such an arrangement, even if the number of lamps of the illumination fixtures in the block is increased, a failure such as bulb life expiration can be precisely detected.</p> |
