Data processing: measuring – calibrating – or testing – Measurement system – Remote supervisory monitoring
Reexamination Certificate
2000-05-22
2002-05-21
Assouad, Patrick (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Remote supervisory monitoring
C340S870160, C315S149000, C315S307000
Reexamination Certificate
active
06393382
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a system and method for remotely monitoring and/or controlling an apparatus and specifically to a lamp monitoring and control system and method for use with street lamps. The present invention includes a monitoring and control unit, such as the lamp monitoring and control unit disclosed in co-pending application entitled “LAMP MONITORING AND CONTROL UNIT AND METHOD”, Ser. No. 08/838,302 the contents of which are incorporated herein by reference.
2. Background of the Related Art
The first street lamps were used in Europe during the latter half of the seventeenth century. These lamps consisted of lanterns which were attached to cables strung across the street so that the lantern hung over the center of the street. In France, the police were responsible for operating and maintaining these original street lamps while in England contractors were hired for street lamp operation and maintenance. In all instances, the operation and maintenance of street lamps was considered a government function.
The operation and maintenance of street lamps, or more generally any units which are distributed over a large geographic area, can be divided into two tasks: monitor and control. Monitoring comprises the transmission of information from the distributed unit regarding the unit's status and controlling comprises the reception of information by the distributed unit.
For the present example in which the distributed units are street lamps, the monitoring function comprises periodic checks of the street lamps to determine if they are functioning properly. The controlling function comprises turning the street lamps on at night and off during the day.
This monitor and control function of the early street lamps was very labor intensive since each street lamp had to be individually lit (controlled) and watched for any problems (monitored). Because these early street lamps were simply lanterns, there was no centralized mechanism for monitor and control and both of these functions were distributed at each of the street lamps.
Eventually, the street lamps were moved from the cables hanging over the street to poles which were mounted at the side of the street. Additionally, the primitive lanterns were replaced with oil lamps.
The oil lamps were a substantial improvement over the original lanterns because they produced a much brighter light. This resulted in illumination of a greater area by each street lamp. Unfortunately, these street lamps still had the same problem as the original lanterns in that there was no centralized monitor and control mechanism to light the street lamps at night and watch for problems.
In the 1840's, the oil lamps were replaced by gaslights in France. The advent of this new technology began a government centralization of a portion of the control function for street lighting since the gas for the lights was supplied from a central location.
In the 1880's, the gaslights were replaced with electrical lamps. The electrical power for these street lamps was again provided from a central location. With the advent of electrical street lamps, the government finally had a centralized method for controlling the lamps by controlling the source of electrical power.
The early electrical street lamps were composed of arc lamps in which the illumination was produced by an arc of electricity flowing between two electrodes.
Currently, most street lamps still use arc lamps for illumination. The mercury-vapor lamp is the most common form of street lamp in use today. In this type of lamp, the illumination is produced by an arc which takes place in a mercury vapor.
FIG. 1
shows the configuration of a typical mercury-vapor lamp. This figure is provided only for demonstration purposes since there are a variety of different types of mercury-vapor lamps.
The mercury-vapor lamp consists of an arc tube
110
which is filled with argon gas and a small amount of pure mercury. Arc tube
110
is mounted inside a large outer bulb
120
which encloses and protects the arc tube. Additionally, the outer bulb may be coated with phosphors to improve the color of the light emitted and reduce the ultraviolet radiation emitted. Mounting of arc tube
110
inside outer bulb
120
may be accomplished with an arc tube mount support
130
on the top and a stem
140
on the bottom.
Main electrodes
150
a
and
150
b
, with opposite polarities, are mechanically sealed at both ends of arc tube
110
. The mercury-vapor lamp requires a sizeable voltage to start the arc between main electrodes
150
a
and
150
b.
The starting of the mercury-vapor lamp is controlled by a starting circuit (not shown in
FIG. 1
) which is attached between the power source (not shown in
FIG. 1
) and the lamp. Unfortunately, there is no standard starting circuit for mercury-vapor lamps. After the lamp is started, the lamp current will continue to increase unless the starring circuit provides some means for limiting the current. Typically, the lamp current is limited by a resistor, which severely reduces the efficiency of the circuit, or by a magnetic device, such as a choke or a transformer, called a ballast.
During the starting operation, electrons move through a starting resistor
160
to a starting electrode
170
and across a short gap between starting electrode
170
and main electrode
150
b
of opposite polarity. The electrons cause ionization of some of the Argon gas in the arc tube. The ionized gas diffuses until a main arc develops between the two opposite polarity main electrodes
150
a
and
150
b
. The heat from the main arc vaporizes the mercury droplets to produce ionized current carriers. As the lamp current increases, the ballast acts to limit the current and reduce the supply voltage to maintain stable operation and extinguish the arc between main electrode
150
b
and starting electrode
170
.
Because of the variety of different types of starter circuits, it is virtually impossible to characterize the current and voltage characteristics of the mercury-vapor lamp. In fact, the mercury-vapor lamp may require minutes of warm-up before light is emitted. Additionally, if power is lost, the lamp must cool and the mercury pressure must decrease before the starting arc can start again.
The mercury-vapor lamp has become one of the predominant types of street lamp with millions of units produced annually. The current installed base of these street lamps is enormous with more than 500,000 street lamps in Los Angeles alone. The mercury-vapor lamp is not the most efficient gaseous discharge lamp, but is preferred for use in street lamps because of its long life, reliable performance, and relatively low cost.
Although the mercury-vapor lamp has been used as a common example of current street lamps, there is increasing use of other types of lamps such as metal halide and high pressure sodium. All of these types of lamps require a starting circuit which makes it virtually impossible to characterize the current and voltage characteristics of the lamp.
FIG. 2
shows a lamp arrangement
201
with a typical lamp sensor unit
210
which is situated between a power source
220
and a lamp assembly
230
. Lamp assembly
230
includes a lamp
240
(such as the mercury-vapor lamp presented in
FIG. 1
) and a starting circuit
250
.
Most cities currently use automatic lamp control units to control the street lamps. These lamp control units provide an automatic, but decentralized, control mechanism for turning the street lamps on at night and off during the day.
A typical street lamp assembly
201
includes a lamp sensor unit
210
which in turn includes a light sensor
260
and a relay
270
as shown in FIG.
2
. Lamp sensor unit
210
is electrically coupled between external power source
220
and starting circuit
250
of lamp assembly
230
. There is a hot line
280
a
and a neutral line
280
b
providing electrical connection between power source
220
and lamp sensor unit
210
. Additionally, there is a switched line
280
c
and a neutral line
28
Williams Larry
Young Michael F.
A. L. Air Data, Inc.
Assouad Patrick
Fleshner & Kim LLP
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