350
MODERN GASWORKS PRACTICE
Fig. 253.— Totally-Enclosbd Motor with Gbar-Brackbi MOUNTED BELOW.
to be detected should be fixed, and on large installations meters recording tlie consumption of power on eacli feeder, on the amount generated by each generating set, can usefully be fitted.
A distributing board is usually required in the retort house and the feeder cable from the generating plant is bro right into this board and there divided up into a number of circuits, one of which goes to each motor. It is usual to provide fuses and in some cases switches and fuses at the point where the circuits a r e divided up. In addition each motor must be pro-tected by its own starting panel, and it is advisable to have a combined type of panel fixed reasonably near the motor for the control of the individual motor. This panel should contain a starter with a “ no-volt ” and overload release (these releases automatically protect-ing the motor in case of overload), together witli a double pole circuit breaker or
a double pole switch and fuses. The overload release cuts off the current when it reach.es a prearranged amperage should there be an unforeseen stoppage or “ jam-ming-up ” of the coal plant, and in this way the windings of the motor are pre-vented from being burned out. Again, the starter may be left on by accident or inattention, and when the current is off the “ no-volt ” release brings it back to “ off,” this preventing burning out should the main switch, be closed in the absence of the operator. Totally enclosed switch es should be made use of on the retort-house panel, the whole being boxed in and fitted with a glass panel for observation purposes.
CABLES AND WIKING
It is a debatable point as to which is the best type of wiring to instal. In general, however, wiring laid in the ground should be avoided, owing to the difficulty of locating faults, and it is generally advisable to keep everything in a position where it can easily be got at and overhauled. The best policy is, perhaps, to