AN INGENIOUS DEVICE

Otago Witness, Issue 4029, 2 June 1931, Page 76

AN INGENIOUS DEVICE

DUNEDIN ENGINEER’S INVENTION. IMPROVED ELECTRIC POWER CONTROL. As a result of the untiring work and initiative of Mr R. D. Veitch, assistant engineer to the Otago Electric Power Board, a very important piece of machinery has been designed and developed, and sets are now being installed at the board’s various sub-stations throughout the district. The machinery is known as re-closing gear, and its work is to . replace the switches at the sub-stations when these have been “ tripped,” or thrown out by reason of some fault occurring on a power line. Before the installation of such gear .the practice was, when a switch’ was automatically thrown out, for one of the staff on the section to replace it by hand, and it frequently happened that a switch might be out for a considerable period, and the district, or portion of it, deprived of power during that time. During the time the designer was engaged on the preliminary work, which occupied about two months, he had before him the three objects of the gear—namely: —

1. A mechanism was required which would automatically re-close switches thrown out by faults on a line. Such a fault might be caused by a bird flying into the line and causing a short circuit. It was necessary that, between the time the switch “ tripped ” and the time the gear should re-close the switch, a short period should elapse so that the fault, might have an opportunity of clearing itself. In the instance mentioned, the bird would be given time to fall clear of the line.

2. The mechanism would be required to re-close the switch a given number of times and no more, so that, if the frault were serious, such as a broken line, the gear would go on re-closing the switch indefinitely each time the breaker tripped.” The gear has been designed so th<it it will re-close three times and will then, if the switch comes out again, lock it out until the fault is repaired and the switch put back a„ain by the linesmen. °

3. Supposing the fault were to be cleared after one complete reclosing, the gear would be required to come back automatically to its original condition so that, in the event of a subsequent fault occurring, it would bo able to recloso again three times without any readjustment having been made by hand. Mr Veitch succeeded in perfecting a machine which would meet with all these demands, and he has since developed it so that one set of gear can operate several switches in one switch-house and can select the correct switch to operate when a fault occurs.

In the board’s district 10 sets are now in use and two more are ready to be installed. The whole of the gear is made in the board’s workshops and it has the advantage that it costs only a little more than half of the amount that would have to be paid for imported gear, and, at the same time, it is much simpler in construction and working than the gear manufactured in England and America.