Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Combined
Reexamination Certificate
2002-03-25
2004-10-26
Deb, Anjan (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Combined
C324S127000, C324S107000
Reexamination Certificate
active
06809509
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electrical 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
and the available space within the power panel
10
may be insufficient for the desired number of current sensors. Also, the limited space available along the circuit breakers
16
may result in significant difficulty installing the current sensors
20
, thus requiring lateral spacing of the current sensors and bending the wires from the circuit breakers to different locations within the power panel
10
in an attempt to locate sufficient available space for the current sensors
20
. In addition, the large number of wires
22
from the current sensors
20
to the current monitor
24
may require considerable space within the power panel
10
. Further, 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
. In summary, the potential installation problems are significant, especially when install by untrained technicians.
Referring to
FIG. 3
, a design sold by Veris Industries, LLC is a three phase current sensor
40
. A set of separate housings
42
a
,
42
b
, and
42
c
enclose respective single phase current sensors and related electronics. The separate housings
42
a
-
42
c
are glued together to create a three phase current sensor. A set of wires, each of which have a single electrical phase
46
a
,
46
b
, and
46
c
of a three phase circuit is inserted through the current sensors within the respected housings
42
a
,
42
b
, and
42
c
. The output of each of the current sensors is a current proportional to the current in the respective wire
46
a
-
46
c
. The current sensor within each of the housings
42
a
-
42
c
are interconnected in series providing a single pair of outputs
44
. If the current in one of the phases of the three phase circuit is over a threshold, then the respective current sensor provides an open circuit condition at its respective terminals. If one of the current sensors is open circuited then that condition is reflected at the outputs
44
.
What is desired, therefore, is an effective electrical measurement system.
REFERENCES:
patent: 5861683 (1999-01-01), Engel et al.
patent: 5880677 (1999-03-01), Lestician
patent: 5995911 (1999-11-01), Hart
patent: 6064192 (2000-05-01), Redmyer
patent: 6373238 (2002-04-01), Lewis et al.
patent: D466078 (2002-11-01), Bowman
Bowman Marc
Bruno David
Seely Rodrick
Chernoff, Vilhaufer, McClung & Stenzel, LLP
Deb Anjan
Veris Industries, LLC
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