Metering electricity supply

The electricity supply to the factory is usually obtained from the public supply authority, who will need to install metering in order to be able to assess the charges due in accordance with the agreed tariff. This metering will be the responsibility of the energy supplier but, in order to ensure that the rights of the customer are protected, the design of this instrumentation, and the accuracy limits... 

Connect the cold-water supply line with a solenoid valve to the distribution tube. Make sure the float system used to control the water level in the tank is operating freely and connected to the solenoid valve. Check if the solenoid valve is connected to an electrical supply. Turn on the water supply. Observe the water level. It should be slightly below the overflow if it is not, adjust the level float system. A water flow rate of 2 gpm should be sufficient and should register satisfactorily on a in. meter. 

Electricity supply authorities discourage the use of equipment and installations with a low power factor because they absorb part of the capacity of the generating plant and the distribution network to no useful effect. They, therefore, penalize industrial consumers with a bad power factor through a maximum demand tariff, metered at the consumer s intake position. If the power factor falls below a datum level of between 0.85 and 0.9 then extra charges are incurred. In this way industrial consumers are encouraged to improve their power factor. 

The electricity supply companies generally use single-core PVC-insulated and sheathed conductors without further protection for the connections between their cut-outs, metering equipment and the consumer s main switchfuse or circuit breaker, and very often this wiring is not properly secured. It is not, therefore, as safe as the site installation wiring, so access to it should be restricted to authorised and competent persons. Any building or... 

A normal modern intake into a house comprises a CNE concentric service cable terminating in a plastic sealing box. The supply company provides an earthing terminal connected to the cable sheath, which is the CNE conductor, and a cut-out consisting usually of a 60 A or 100 A BS 1361 fuse. The meter tails are generally PVC insulated and sheathed conductors. The Electricity Supply Regulations require them to be marked for polarity. Quite... 

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. 

In other designs, a diffused siUcon sensor is mounted in a meter body that is designed to permit caUbration, convenient installation in pressure systems and electrical circuits, protection against overload, protection from weather, isolation from corrosive or conductive process fluids, and in some cases to meet standards requirements, eg, of Factory Mutual. A typical process pressure meter body is shown in Figure 10. Pressure measurement from 0—746 Pa (0—3 in. H2O) to 0—69 MPa (0—10,000 psi) is available for process temperatures in the range —40 to 125°C. Differential pressure- and absolute pressure-measuring meter bodies are also available. As transmitters, the output of these devices is typically 4—20 m A dc with 25-V-dc supply voltage. 

This surprising equality arises because an efficient appliance saves expensive electricity at the meter, at an average retail price of 8 cents/kWli whereas one kWh of new wholesale supply is worth only 2-3 cents at the power plant. Thus, even if electricity from some future new remote power plant is too cheap to meter, it still must be transmitted, distributed, and managed for 5—6 centsAWh. It is impossible to disentangle the contribution of standards and of accelerated improvement in technology, but clearly the combination has served society well. 

Telephones/intercom Protection equipment Electrical controls, inst. meters Lighting and small power Temporary supplies Elec, hace heating Generator AVR... 

The switchgear provided at the installation for the provision of the supply by the supply authority will be the property of that authority. That provided for the distribution of the electricity around the installation will be the property of the consumer, while metering for tariff purposes will be located on or supplied from the supply authority switchgear. 

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