Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Magnetic saturation
Reexamination Certificate
2002-03-26
2004-05-18
Nguyen, Vinh P. (Department: 2829)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Magnetic saturation
C324S126000
Reexamination Certificate
active
06737854
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a current monitoring system.
Referring to
FIG. 1
, many electrical power distribution systems include a power panel enclosure
10
into which is provided electrical power using one or more sets of wires
12
. The electrical power may have any voltage, any current, and any number of phases (e.g., single phase, two phases, or three phases). Each phase of the electrical power to the power panel is normally provided to a separate bus bar
14
a
,
14
b
, and
14
c
, which are normally elongate conductors within the power panel
10
. A plurality of circuit breakers
16
a
,
16
b
,
16
c
, etc., which trip or otherwise selectively disconnect electrical power, are electrically interconnected between one or more of the bus bars
14
a
,
14
b
, and
14
c
, and respective loads
18
external to the power panel
10
. In many power panels
10
the circuit breakers
16
are vertically aligned in one or more strips
20
and
22
. When the load
18
interconnected to a respective circuit breaker
16
within the power panel
10
draws excessive electrical current then the circuit break
16
trips or otherwise disconnects the electrical power to the load
18
. In this manner, if a load shorts and thereafter draws excessive current then the circuit breaker will trip.
In a business or residential environment a set of electrical loads, such as motors, outlets, heaters, lights, machinery, instrumentation, etc., may be electrically interconnected to a single circuit. When the electrical current provided to the loads from a single circuit is excessive then the respective circuit breaker(s) will disconnect the electrical power to all of the loads. Initially, the anticipated current requirements for all of the loads interconnected to a single circuit breaker(s) may be added together to ensure that the total load will be sufficiently below the rating for the circuit breaker. In this manner, the circuit breaker will not inadvertently trip with normal variations in the current drawn by the loads. However, after the initial installation of the loads and a suitable circuit breaker for those loads, additional loads are frequently added to existing circuits without sufficient consideration of the total existing load for the respective circuit breaker(s). If excessive additional loads are added to the circuit breaker(s), then the circuit breaker(s) will have a tendency to trip during normal operation. While this may be generally acceptable in a residential environment, in a business environment the unanticipated tripping of the circuit breaker, especially when none of the loads are actually shorted, is simply unacceptable.
For example, in a computer server farm environment five circuit breakers may each be electrically interconnected to five computer servers, having a total of twenty-five computer servers. If three additional computer servers are added to the computer server farm, they may be electrically interconnected to the same circuit breaker. Frequently the installer is in a hurry to install the three additional computer servers to the network and interconnects the additional three computer servers to any readily available power outlet. However, having eight computer servers electrically interconnected to a single circuit breaker, which is properly sized for only five computer servers, will likely result in tripping the circuit breaker during normal usage. This may be simply unacceptable for operating a computer server farm where uninterrupted service is important. In many cases, the power provider to the server farm guarantees up time of the power provided to the computer servers. In the event that the power is interrupted, the power provider may be required to pay a substantial financial penalty.
Referring to
FIG. 2
, to monitor the current levels of individual circuit breakers
16
a respective current sensor
20
may be interconnected to the wire on the load side of the respective circuit breaker
16
. The outputs
22
of each of the current sensors
20
may be interconnected to a current monitor
24
which signals an alarm condition if the output of one of the current sensors is to high. The current sensors
20
may be interconnected to one or more current monitors. It takes considerable time to install, at significant expense, all of the current sensors
20
. In addition, because of the significant number of individual wires
22
an installer has a significant tendency to interconnect the wires
22
to improper places within the current monitor
24
and in particular to mismatch pairs of wires
22
from the same current sensor
20
rending the current sensors
20
ineffective. Moreover, it is problematic to ensure that the wires
22
indicated by the installer that relate to a particular current sensor
20
actually are interconnected to the desired current sensor
20
. Typically, an installer likewise programs the current monitor
24
to indicate which wires attached to its interface are associated with which circuit breaker, and thus which load. Without proper attachment of the matched pairs of wires and attaching the wires in the proper location, any information that may be obtained may be simply nonsensical and relate to the wrong load (circuit breaker(s)), respectively. In summary, the potential installation problems are significant, especially when installed by untrained technicians.
What is desired, therefore, is an effective electrical measurement system.
REFERENCES:
patent: 4709339 (1987-11-01), Fernandes
patent: 6373238 (2002-04-01), Lewis et al.
Bowman Marc
Bruno David
Chernoff Vilhauer McClung & Stenzel LLP
Nguyen Vinh P.
Veris Industries, LLC
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