Meter device and method of testing a cut neutral conductor

A meter device for checking the measurements of an electrical meter, such as that used by electrical utilities is provided. The meter device has a base with electrical phase conductors arranged to couple with a meter socket. A housing is attached to the base. Electrical connectors are arranged on the end of the phase conductors within the housing. The electrical connectors are arranged to couple with an electrical meter. One or more lead conductors is also provided. Each lead conductor has a first end coupled to the electrical connector and a second end coupled to the associated phase conductor. Each lead conductor includes a middle portion arranged outside of the housing.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to device for testing electrical service, and in particular to a device for electrical meters that allows the independent testing of electrical measurements made by the electrical meter.

Electrical meters are used to provide a measurement of the amount of electrical power consumed by a customer. Electrical meters are typically installed by a utility at a customers facility adjacent the location where the electrical power line enters the building. Electrical meters typically have an interface, such as an electronic display or a set of dials for example, that allows both the customer and the utility to review the amount of electrical power measured by the meter. The electrical meters are periodically (e.g. monthly) read by the utility to determine how much the customer should be billed. The meters may be read by sending personnel to each meter to record the measurements, or the data may be transmitted electronically to the utility. It should be appreciated that it is desirable that the electrical meter accurately measure the amount of electrical power consumed.

Periodically, it is desirable to test the measurements of the electrical meter to ensure that the measurements are accurate. Measurements by the meter could vary for a number of reasons, such as meter component failure, tampering or a broken or cut neutral conductor for example. To make these measurements, the utility typically needs access to the customer's circuit breaker panel. As a result, the testing needed to be scheduled when the customer was available to allow access to the facility. Often resulting in an inconvenience for the customer and the utility.

While existing devices and methods for checking the accuracy of electrical meters are suitable for their intended purposes, improvements may be made in allowing testing of the electrical meter location without entering a customer's facility.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a meter device is provided having a base. The base includes a first phase conductor and a second phase conductor extending therethrough. A housing is coupled to the base. A first stab is arranged in the housing and is electrically coupled to the first phase conductor. A second stab is arranged in the housing and is electrically coupled to the second phase conductor. A first lead conductor is electrically coupled between the first stab and the first phase conductor. A second lead conductor is electrically coupled between the second stab and the second phase conductor. A first insulation member covers the first lead conductor, the first insulation member having a first gap. A second insulation member covering the second lead conductor, the second insulation member having a second gap. A first cover is movably coupled to the first insulation member. A second cover is movably coupled to the second insulation member.

According to another aspect of the invention, a meter device is provided having a housing with a wall. A base is coupled to the housing. A first phase leg conductor is coupled to the base. A neutral conductor is coupled to the base. A first lead conductor having a first and second end is electrically coupled to the first phase leg conductor, the first lead conductor having a first loop portion extending through the wall. A first insulation member is disposed over the first lead conductor and extends from a first end to the first loop portion. A second insulation member is disposed over the first lead conductor and extends from a second end to the first loop portion, wherein the first insulation member and the second insulation member define first gap therebetween. A first cover is movably coupled to the first lead conductor. A neutral terminal is coupled to the wall, the neutral terminal being electrically coupled to the neutral conductor.

According to yet another aspect of the invention, a method of checking a neutral conductor on an electrical meter having at least one phase conductor is provided. The method includes the step of removing the electrical meter from a meter socket. A meter adapter is installed having at least one lead conductor electrically coupled to the at least one phase conductor and a neutral terminal. The electrical meter is installed on the meter adapter. An induction meter is coupled to the at least one lead conductor. A first measurement of electrical power is measured with the induction meter. The neutral terminal is coupled to an external neutral. A second measurement of electrical power is measured with the induction meter. A deviation is determined between the first measurement and the second measurement.

DETAILED DESCRIPTION OF THE INVENTION

An exemplary embodiment of a meter device20is illustrated inFIGS. 1-6. The meter device20includes a base22coupled to a housing24. The base22includes a first pair of first phase conductors26, a second pair of second phase conductors28and a neutral conductor30. The conductors26,28,30extend from a bottom surface34. In the exemplary embodiment, the base22and conductors26,28,30are generally adapted to interface with a standard electrical meter socket32(FIG. 7), such as those used by electrical utilities on residential and commercial buildings for example.

The housing24includes a first wall36, with a second wall38extending about its periphery. The walls36,38define an interior portion40. A plurality of standoffs42extends from the first wall36into the interior portion40. Each of the standoffs42includes an opening43to allow wires and conductors to pass through. The conductors26,28,30extend through the standoffs42into the interior portion40. The first phase conductors26are coupled to stabs44,45. The second phase conductors28are coupled to stabs46,47. The neutral conductor30is coupled to a stab48. In the exemplary embodiment, each of the stabs44,45,46,47,48are adapted to interface with corresponding conductors (not shown) in an electrical meter50(FIG. 7). A wire52electrically connects the neutral stab48to a neutral terminal54mounted on the outer surface of the second wall38.

The meter device20also includes a first lead conductor56and a second lead conductor58. As will be discussed in more detail below, the first lead conductor56and second lead conductor58allow and operator to take measurements of electrical power with the electrical meter50installed. The first lead conductor56includes a first end60electrically coupled to the stab44. The first lead conductor56extends from the first end60through an opening62in the second wall38. The first lead conductor56then loops, forming a first middle portion64and reenters the interior portion40through a second opening70in second wall38. A second end68of the first lead conductor56passes through an opening43in the standoffs42and connects to the first phase conductor26in the base22opposite the stab44. A first insulation member72is disposed over the first lead conductor56adjacent the first end60. The first insulation member72ends through the opening62and over a portion of the middle portion64. A second insulation member74is disposed over the first lead conductor56adjacent the second end68. The first and second insulation members72,74are made from an electrically insulating material.

The first and second insulation members72,74cooperate to define a gap76in the middle portion64. In one embodiment, an electrically conductive first coil78is disposed in the gap76. The coil78may be made from a suitable electrically conductive material such as copper for example. A first cover member80is disposed about the first insulation member72. The first cover member80is moveable between a first position shown inFIG. 6and a second position shown inFIG. 1. When arranged in the second position, the first cover member80substantially covers the gap76. In one embodiment, the first cover member80is sized to cover the gap76and a portion of the first and second insulation members72,74when in the second position. The first cover member80is made from an electrically insulating material, such as rubber for example.

The second lead conductor58is arranged in a substantially identical manner as the first lead conductor56. The second lead conductor58includes a first end82electrically coupled to stab46. The second lead conductor58extends therefrom through an opening84in second wall38forming a second middle portion86. The second lead conductor58re-enters the interior portion40through an opening88. A second end90extends through opening43in one of the standoffs42and is connected to the first phase conductor26opposite the stab46. Similarly a third insulation member92is disposed over the second lead conductor58adjacent the first end82and a fourth insulation member94is disposed over the second lead conductor58adjacent the second end90. The third and fourth insulation members92,94cooperate to define a gap96in the middle portion86. A second coil98is disposed in the gap96and a second cover member100is movably disposed over the third insulation member92. Similar to the first cover member80, the second cover member100is movable between a first position (FIG. 6) and a second position (FIG. 1). In one embodiment, the second cover member100is sized to span the gap96and a portion of the third insulation member92and the fourth insulation member94while in the second position.

It should be appreciated that the lead conductors56,58are electrically coupled to the first phase conductor26and the second phase conductor28and that electrical current flowing through the phase conductors26,28also flow through the respective lead conductors56,58. This provides advantages in measuring the individual phases separately. It should further be appreciated that while the embodiments described herein refer to a two-phase electrical meter, the claimed invention should not be so limited. A single-phase meter device20is also contemplated and would be substantially similar to that described herein however, only a single-phase conductor would be used with a single lead conductor for example.

Referring now toFIGS. 7-8, one method of operating the meter device20is illustrated. It is desirable to test the accuracy of the measurements made by the electrical meter50without entering the building or facility that the electrical meter50is connected. First, the electrical meter50is removed and the meter device20installed in the meter socket32. The electrical meter50is then installed on the meter device20. It should be appreciated that since the phase conductors26,28provide a direct electrical connection from the electrical meter50to the meter socket32, the electrical meter50may measure the flow of electrical current as if it were installed in the meter socket32.

With the meter device20installed, a number of tests may be performed. In the embodiment illustrated inFIG. 7, a load inducer102includes a first cable106coupled to the neutral terminal54and a second cable108coupled to one of the coils78,98. To install the second cable108, one of the cover members80,100is moved from the second position to the first position to expose the underlying coil78,98. It should be appreciated that the cover member for the electrical phase not being tested remains in the second position covering the respective coil. In this embodiment, the electrical meter50may be electrically isolated from the building or load by placing insulators104(FIG. 4) over the phase conductors26,28. The load inducer102simulates a known quantity of load or flow of electrical current. With the load inducer102installed and operating, the operator can test the meter potentials and dial rotation. This provides the advantage of allowing the operator to validate the meter readings and determine if the electrical meter50has been tampered with or if there is a malfunction.

Other tests may also be performed. In the embodiment illustrated inFIG. 8, the electrical meter50is coupled to the customers load such that the electrical meter50is measuring the electrical power consumed. An induction meter110is coupled to one of the lead conductors56,58. Since the lead conductors56,58are electrically coupled to the phase conductors26,28, the induction meter110can measure the electrical current flowing into the connected building. By measuring for a time period, such as with a stopwatch112for example, the operator may determine the electrical power consumed and compare this measurement with that measured by the electrical meter50. Similar to the embodiment ofFIG. 7, the performance of the electrical meter may be validated and tampering or malfunctions determined without requiring the operator to enter the building the electrical meter50is connect to. It should be appreciated that the testing could be performed on each electrical phase by connecting the induction meter110to each lead conductor56,58sequentially.

One other potential source of errors in the electrical meter50occurs when a neutral conductor has been severed or cut within the building to which the electrical meter50is connected. Referring now toFIGS. 9-10, a method114of detecting or validating a severed neutral conductor will be described. The method114starts in block116and proceeds to block118where the electrical meter50is removed. The meter device20is installed in block120and the electrical meter50installed on the meter device20in block122in a similar manner to that as described herein above.

An induction meter110is installed on one of the lead conductors56,58in block124. The electrical current is measured with the induction meter for a time period (as measured with stop watch112for example) in block130. The amount of electrical power consumed may be determined from knowing the voltage, current and time. Next, in block132, an external neutral conductor is connected by attaching an electrical cable126to the neutral terminal54. The opposite end of the electrical cable126is placed in electrical contact with a known ground, such as a pipe128for example, to create an external neutral conductor.

With the external neutral in place, the operator once again measures the electrical current for a period of time in block134. Method114then proceeds to block136where the deviation between the measurements with and without the external neutral connected is determined. In query block138, it is determined whether the deviation or error in the measurements is beyond a threshold. If the deviation is greater than the threshold, then method114proceeds to block140where it is determined that the neutral conductor has been severed. After it has been determined that the neutral conductor was severed, or if query block138returns a negative (e.g. the measurements are similar), then the method113stops in block142. The method114may be repeated for each electrical phase by moving the induction meter110from the first lead conductor56to the second lead conductor58and repeating steps described herein.