DEVICE AND METHOD FOR BALANCING IN FIELD SINGLE-PHASE INDIVIDUAL METER LOADS
IN A STACK OF MULTIPLE THREE-PHASE METERS
Field of the Invention The present invention relates to multiple meter base stacks, and specifically to field load balancing of individual single phase meters within a stack of three phase meters. Background of the Invention Power companies provide single-phase power to tenant facilities, such as apartment buildings or small commercial offices, through meter centers. Each meter center includes main disconnecting means and overload protection, such as a circuit breaker or fused switch, and an individual electrical meter for each tenant receiving electrical service. The electric power company supplies three-phase power to a main service panel that houses the main disconnect and overload protection devices and a three-phase feeder busbar connected to the load side of the overload protection device. The single-phase energy for each tenant is taken from one of the combinations of phases A-B, A-C or B-C of the three-phase supply through individual meters housed in a meter module or stack of meters that is added to the main service panel. It is important that the tenant charges are balanced between the combinations of phases A-B, A-C and B-C to prevent overheating of the conductors and for a more efficient use of electricity. This has generally been achieved by trying to have an equal number of tenants in each of the combinations of phases A-B, A-C and B-C. Due to the cost, the most common method of balancing loads has been to provide measuring modules having two or more bases of
• meter and a single-phase connector bar that can be connected to one of the combinations of phases A-B, A-C or B-C of the three-phase feeder busbar. In this configuration, at least one meter module is required for each of the
combinations of phases A-B, A-C and B-C in order to provide at least one meter connection in each of the combinations of phases A-B, A-C and B-C. An alternative is to provide a module
• meter having a three-phase connector bar with a meter base connected to each of the combinations of phases A-B,
A-C and B-C. Metering modules of these types are disclosed in U.S. Patent Nos. 3,628,097, issued December 24, 1971 to Kobryner, and 4,041,358, issued August 9, 1977 to Donahue et al. None of these settings focuses properly
situations in which the number of tenants is not a multiple of three or where changes in use by tenants-or other events can significantly alter the balance of charges and require a re-balancing of the load based on the calculated charges of the tenants. The meter bases in the devices described above are provided with factory-made line connections that are not intended to be changed in the field, and it is generally difficult to work with them. Therefore, the only method of rebalancing the load is to disconnect one or more tenant feeder cables from the load side of their meter bases and reconnect them to the load side of another meter base that is connected to a combination of phases AB, AC or BC different. This can be a difficult and time-consuming job, which requires that the affected tenant (s) be without power for the time required to make the necessary load-balancing changes. Therefore, it would be desirable to have a meter base module with provisions to easily and quickly change the line connections of the meter base of any meter base in the module between any of the combinations of phases A-B, A-C or B-C. SUMMARY OF THE INVENTION The present invention provides a stack of meters where each meter base in the stack of meters can be electrically connected to any of the combinations of phases AB, AC or BC of vertical three-phase connecting rods in the stacking of meters by moving only the meter base line connectors. The vertical connector bars lie in a common plane and are spaced from each other. The vertical center line of each meter base in the module matches the center line of the central vertical connector bar of the meter module. Each of the two line-side terminals of each meter base is associated with one of the external vertical connector bars, and is located midway between its associated external vertical connector bar and the central connector bar. A generally "Z" shaped line connector, attached to each of the line terminals, can be easily rotated between its associated connector bar and the central connector bar, thus allowing a change in the AB, AC or BC phase combinations. of each meter base. Brief Description of the Drawings Figure 1 is a front view of a stack of meters, according to the present invention. Figure 2 is a front view of vertical connector bars and meter bases of a stack of meters according to the present invention. Figure 3 is an isometric view of the meter baseline connector according to the present invention. Before an embodiment of the invention is explained in detail, it will be understood that the invention is not limited in its application to the details of construction and description or illustrated in the drawings. The invention is capable of other embodiments and of being implemented or carried out in various other ways. Likewise, it will be understood that the phraseology and terminology used herein are for description purposes and should not be considered as limiting. Description of the Preferred Embodiment Form Figure 1 illustrates a stack of meters of the present invention, generally indicated by the reference number 10. The stack of meters 10 includes a housing 14 provided with meter covers 18, each having an opening 22 to receive an electric meter. A meter base 26 with its line terminals 30, load terminals 34 and line connectors 38 and the vertical connector bars 42, 46 and 50 can be seen through each meter opening 22. Vertical connector bars 42, 46 and 50 are connected to a horizontal connector bar (not shown), which in turn is connected to the load side of the main disconnect device in the main service panel. Figure 2 illustrates the arrangement of the three three-phase vertical bars 42, 46 and 50 with respect to the meter bases 26 in the meter stack 10. The vertical center line of each meter base 26 matches the center line of the bar central connector 46 and line terminals 30 of each base 26 are positioned outside the connector bars 42 and 50. Each of the connector bars 42, 46 and 50 has a fixed fastener such as a bolt 54 adjacent to the line terminals 30 of each meter base 26 such that the bolts 54 associated with a meter base 26 are aligned and extend upward toward the meter bases 26. Each meter base line terminal 30 is connected to one of the connector bars verticals 42, 46 or 50 by a line connector 38. Referring now to Figure 3, it can be seen that the line connector 38 is generally "Z" shaped and in the preferred embodiment has a slot opening 58 at one end and an elongated hole 62 at the other end. The elongated hole 62 is used to hold the line connector 38 to the meter base line terminal 30 with a threaded fastener and the slotted opening 58 slidably receives the pin 54 from one of the vertical connector bars 42., 46 or 50 and secured to it by means of a nut 66. When it has been determined that the load is not properly balanced among the tenants, the load of each tenant must be measured or calculated. Using the measured or calculated load information, one or more tenants can be switched to another of the combinations of phases A-B, A-C or B-C to balance the load with greater precision. This is accomplished by turning off the main disconnect, removing the selected tenant electric meter from its meter base 26, loosening the threaded fasteners of the desired line connector 38, and rotating the line connector 38 to the other vertical connector bar 42, 46 or 59 to which it can be connected, by retightening the threaded fasteners, replacing the electric meter of the tenant in the meter base 26 and activating the main disconnect again.