Busbars fittings

Busbars. Fitting the tank for d-c power is usually accompHshed usiag round copper busbars, both for supporting the anodes and the work or cathodes. Size of the copper bus is determined by the amount of current flow expected 1000 amperes requires about 6.5 cm of cross-sectional area. The bus is iasulated from the tank, and any other sources of grounding, and coimected to the d-c power supply. Shorter distances from the tank as well as fewer electrical connections keeps the voltage drop to a minimum. 

Only high tensile (HT) fasteners must be used for busbar Jointing and their interconnections or links not only to take care of the fault level but to also maintain the recommended contact pressure over a long period of operation as noted in Table 29.1. An ordinary fastener may not be able to withstand or sustain this torque for long. Similarly, the busbar supports, which are mounted on only two or three fasteners, should also be fitted with these fasteners. 

As shown in Figure 29.1 (a) as a result of loose fit of busbars with an unequal gap, the insulators (shaded in the figure) may fail for Ihe following reasons ... 

A loose fit of busbars itiside the slots may cause e.xcessive vibrations on a fault and may lead to loosening of the fasteners and shearing of the wedges and/or the edges and the fingers of the insulators. Even the insulator mounting section. v - x may become vulnerable to failure. 

Cubicle steelwork is invariably bolted to the floor, a floor frame or to a wall structure, and therefore bolted bonding straps are used in a similar manner as described above. Most cubicles are fitted with an internal copper busbar which is bonded internally to the steel. The busbar is used to receive the bonding connections from internal components, partitions, screening panels, cable glands, cable armouring, cable screens and gland plates. 

Each switchboard in the main distribution network can have its own one-line diagram displayed, and for the more complicated switchboards each busbar section can be displayed. The active and reactive power flows and current flows can be shown for each item where suitable analogue transducers have been fitted. This is particularly beneficial for the main power generation switchboard. AU names and tag numbers can be shown for clarity. A diagram similar to Figure 16.1 can be displayed. 

Capacitors may be connected across the main busbars of industrial loads in order to provide power factor improvement, but smaller capacitors may also be connected across an individual piece of equipment, as is the case for fluorescent light fittings. 

Check the position of the meter. The Electricity Supply Regulations require it to be installed in the consumer s premises unless it is more reasonable for it to be located elsewhere, in which case it should be accessible to the consumer. This is more likely to occur in blocks of flats and housing in multiple occupation. In such premises the supply authority may bring in only one service cable on to a busbar and then feed each tenant via cables in conduit or sometimes in MIMS cable. The latter is not a good choice because the insulation is hygroscopic and if the end seals fail, the cable can break down. It may also fail if subject to HV transients, so such cables should be fitted with suppressors. If the conduit or sheath of the MIMS cable is used as the earthing conductor, check that the connections are satisfactory and of low resistance and any joints in the conduit provide adequate continuity. 

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