Electrical transmission or interconnection systems – Switching systems – Condition responsive
Reexamination Certificate
1999-05-24
2001-05-08
Sherry, Michael J. (Department: 2836)
Electrical transmission or interconnection systems
Switching systems
Condition responsive
C340S605000, C137S312000
Reexamination Certificate
active
06229229
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system and method for disabling an electrical device upon sensing a predetermined level of liquid and, more particularly, a system and method for disabling a control device, such as a thermostat for a climate control system, upon sensing a predetermined level of liquid, such as water, in the vicinity of the system.
2. Description of the Related Art
It is well known that during normal operation of a climate control system, such as an air conditioner and/or furnace, water is produced through condensation as a result of the heating or cooling process. Such systems are commonly provided with condensate drain lines for channeling and discharging this water into a sewer system, for example. It is possible, however, for such drain lines to become obstructed or clogged over time, thus causing the condensate (i.e., water) to back up in the drain line and ultimately leak or overflow from another location within the climate control system. For example, it is not uncommon for the condensate drain line on an air conditioner to become clogged, thus resulting in the accumulation of water in the drip pan for the air conditioner until the water ultimately spills over the drip pan. When this occurs, the water may run down onto other components of the climate control system that are positioned below the drip pan, such as a heat exchanger and/or an air handler, and this can lead to corrosion and premature failure of those components. Of course, in the case of electrical components, the overflowing water may create a short circuit condition that could result in immediate damage to the component, and may also create a safety hazard.
In addition to damaging various components of the climate control system, the overflowing water may cause damage to wood floors, carpeting, etc. and, in the case of climate control systems located, for example, in attics or on the second story of a multi-level building, the leaking water may also cause damage to ceilings and anything else located around or below the climate control system, including furniture or other personal items.
A variety of devices are known in the art for disabling electrical devices, including climate control systems, upon detecting an undesirable accumulation of water. In general, however, the known devices are relatively expensive, are difficult to manufacture and/or install, and are generally designed for specific applications. In one such device, a secondary drain line is provided within the primary drain line of an air conditioner for draining condensate water into an auxiliary reservoir when the primary drain line becomes clogged. Positioned within the auxiliary reservoir is a float that can rotate about a pivot point in response to rising water within the auxiliary reservoir. A mercury switch is mounted to the float so that electrical power is provided through the switch and to the thermostat (which controls and enables the air conditioner) when the switch is in a generally horizontal position, but which removes power to the thermostat when the float and switch move to a tilted position as a result of rising water in the auxiliary reservoir. However, the relatively high number of components used in this device, and the manner in which they must be arranged to perform properly, increase the overall cost of the device, including both manufacturing and installation costs, and limit the usefulness of the device to essentially one specific application. The reliance on moving parts will also limit the useful life of the device in the vast majority of applications.
Overall, the known devices for disabling climate control systems upon sensing the presence or accumulation of a liquid require numerous parts, are relatively expensive to manufacture, install and/or service, are tailored for specific, limited applications, and may also suffer from reliability problems. Such devices commonly employ air flow switches, numerous relays, wall panels, and complex circuit arrangements.
What is needed is an arrangement for disabling a climate control system or, more broadly, any type of electrical device upon sensing the presence or accumulation of water or some other liquid, where the device is easily and inexpensively produced and installed, both for new and retrofit applications, where the device performs reliably without moving parts, where the device can be easily reset after a “flood condition” is detected, and that is generally safe to use.
SUMMARY OF THE INVENTION
In order to solve these and other needs in the art, the inventor hereof has succeeded at designing and developing a liquid sensor that can be used to disable an electrical device, such as, for example, the thermostat for a climate control system, upon sensing an accumulation of water or some other liquid in the vicinity of the electrical device. This elegantly simple and inexpensive liquid sensor is suitable for use in virtually any application where disablement of an electrical device upon detecting a liquid is desired.
According to one aspect of the present invention, a system including an electrical device and a power source for the electrical device also comprises a circuit breaker that electrically connects the electrical device to the power source, and a sensor operatively connected to the circuit breaker. The sensor induces an excessive current through the circuit breaker upon sensing a predetermined level of liquid, thus causing the circuit breaker to remove power to the electrical device. The system may be of a type capable of producing or discharging a liquid, such as a climate control system, clothes washer, icemaker, or dehumidifier. The circuit breaker may be of a type that is resettable, or may instead comprise a replaceable fuse. The sensor preferably comprises a first terminal that is electrically connected to the same side of the circuit breaker as the electrical device, as well as a second terminal that is electrically connected to ground. The sensor also preferably comprises two conductors separated by a water permeable insulator.
According to another aspect of the present invention, a system including a control device that enables operation of the system when electric power is supplied to the control device and disables operation of the system when electric power is removed from the control device also comprises a circuit breaker through which the control device receives electric power, and at least a first sensor operatively connected to the circuit breaker. The sensor induces an excessive current through the circuit breaker upon sensing a predetermined level of liquid, thus causing the circuit breaker to remove power to the control device, thereby disabling operation of the system. In the inventor's most preferred embodiment, the system is a climate control system and the control device is a thermostat. The sensor is preferably configured to electrically short the circuit breaker to ground when the sensor is exposed to the predetermined level of liquid. The system may also comprise a second sensor operatively connected to the circuit breaker, also for inducing an excessive current through the circuit breaker upon sensing a predetermined level of liquid. The first and second sensors can be positioned at independent locations.
According to still another aspect of the present invention, a method for disabling an electrical device upon sensing a predetermined level of liquid comprises the steps of providing electric power to the electrical device through a circuit breaker, and inducing an excessive current through the circuit breaker upon detecting the predetermined level of liquid, wherein the circuit breaker removes power to the electrical device in response to the excessive current. The inducing step preferably includes electrically shorting the circuit breaker to ground, and even more preferably, shorting the circuit breaker to ground through a sensor having two conductors separated by a water permeable material. The method also comprises the steps of electrically connecting t
Huynh Kim
Senniger Powers Leavitt & Roedel
Sherry Michael J.
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