PORTABLE SUBSTATIONS

Hauraki Plains Gazette, Volume XXXVI, Issue 4860, 3 August 1925, Page 3

PORTABLE SUBSTATIONS

AN ECONOMIC IAjIICHASE. MOVE BY LOCAL POWER BOARD. In cider to deal speedily and e:--nomically with transformer troubles the Thames Valley Power board has purchased an electric battery truck to be used ,as a portable slib-station. In addition to overhauling, the substation will be used for treating the oil in transformers. It can be used also in cases of emergency for the supply of power should any transformer in the system break down. The truck will carry its own charging plant, so that no matter what part of the district it may be working in it will never need to return to the depot to be charged up. In this respect it differs from the trucks used by the Waltoa factory, for it can be charged from an overhead line. Provision is made for accommodating two men, bunks, and a certain amount of cooking apparatus being provided. The charging set comprises a vertical motor generator set, specially suited for charging the Edison cells witn which the battery is equipped. The power is taken from the overhead line to a transformer in the truck. The power from the the lines is taken at high pressure, namely, 11,000 volts. The transformer in the truck steps this pressure down to 400 volts, at which the motor side of the charging set its supplied. The motor drives a direct current generator which supplies the batteries with suitable power.

In connection with the treatment of oH in the transformers a filter press and drying oven are used. The filter press consists of a large number of sections of blotting paper through which the oil is forced, sediment and moisture being removed in the process. Unless this treatment is given the oil depreciates very much in its insulating qualities, and this tendency makes continual inspections necessary in order tp ensure the proper functioning of the apparatus. The drying oven is used to dry the blotting paper which is used in the filter press, and unices the blotting paper is properly dried good results cannot be obtained from the filter. A certain amount of spare oil will be carried by the truck so that any losses in the transformers in the service can be made good. There is an oil testing set, by means of which will be determined whether the oil in a transformer needs treatment and when sufficient treatment Has been given. There are very few of the trucks in New Zealand, but they will no doubt be much used in future. The truck iis a model of compactness, and it is remarkable that a plant which can do such important work should.be stored in so small a space. The men in charge of the truck may camp anywhere, and lack little provided they are near an electric line. Until the truck arrived it was neces.sary, in order to do this work, to take the transformers into the workshop at Te Aroha.