Apparatus for protecting electrical and electronic equipment and associated method

A protection apparatus includes a relay being switchable between a protected state and an operating state, a power consumption sensor, and a controller for permitting a user to switch the relay to the operating state, and for switching the relay to the protected state responsive to sensed power consumption of the electrical equipment indicating nonuse thereof. Accordingly, the apparatus protects the electrical equipment from disturbances carried by the external electrical conductors when the electrical equipment is not in use. The apparatus preferably includes a housing which also serves to mount a plurality of electrical connectors for interfacing between the electrical equipment and the external electrical conductors. In one embodiment, the apparatus also preferably includes a lightning sensor for switching the relay to the protected state responsive to sensing of lightning. Alternately, or in addition, the apparatus may also include a power loss sensor for sensing a loss of power from the power source to the electrical equipment and for switching the relay immediately to the protected state responsive to sensing a loss of power.

FIELD OF INVENTION 
The invention relates generally to protection equipment, and more 
particularly, to an apparatus and method for protecting electrical and 
electronic equipment from disturbances as may be carried by external 
conductors connected to the equipment. 
BACKGROUND OF THE INVENTION 
Many types of electrical and electronic equipment require connections via 
external conductors to a source of electrical power or other equipment. 
For example, many devices interface to external conductors, such as for 
communication over a telephone line, or connection to a remote antenna. 
Unfortunately, electronic equipment may also experience reduced 
reliability and even a catastrophic failure caused by surges or other 
disturbances carried to the equipment by coaxial, telephone, data, 
control, or power conductors connected to electronic equipment and its 
associated circuitry. 
The disturbances are typically in the form of voltage and/or current spikes 
or surges that may result from transients on the power conductors, for 
example, caused by the switching on and off of large electrical loads 
sharing the power line. Irregularities in the power delivered by the 
utility company supplying the power may also cause potentially damaging 
disturbances. Lightning related surges may also be coupled to sensitive 
electronic equipment via external conductors. In addition, current surges 
caused by power system faults may also damage electrical and electronic 
equipment. 
Many types of arresters, isolation transformers, and suppressors have been 
used in an attempt to provide protection from power line disturbances and 
lightning induced disturbances carried by external conductors. 
Conventional suppression devices typically do not provide a sufficient 
response time or have the energy dissipation capacity to adequately 
protect many types of electrical and electronic equipment. In other words, 
conventional protection devices may not provide a level of isolation 
and/or grounding necessary to fully protect the equipment to which they 
are connected. 
One particularly difficult situation for conventional protection devices 
occurs from a ground potential rise caused by nearby lightning. 
Conventional protection devices may be ineffective against such a ground 
potential rise. Moreover, a common protection scheme is to connect the 
equipment to electrical ground, thus subjecting the equipment to the 
potentially damaging rising ground potential. 
Some common types of protection devices are also turned off when the 
electronic equipment itself is not in use. Unfortunately, the electronic 
equipment is still subject to damage because of its external conductors 
are still connected and these conductors may carry potentially damaging 
electrical disturbances. Many types of conductors may carry undesirable 
disturbances including, for example, power, coaxial, telephone, data, and 
low voltage control lines. 
It is often recommended that certain more sensitive electronic devices, 
such as a computer, a VCR, or a television, for example, be unplugged or 
disconnected from external conductors during extended periods of non-use 
or particularly when a lightning storm is forecast. Such methods while 
potentially effective if rigorously followed are usually inconvenient, 
impractical, or forgotten. Typically, one simply forgets to disconnect the 
electronic equipment. 
U.S. Pat. No. 4,095,262 to St. Clair, for example, is directed to 
protecting household appliances, such as a TV, for example, from high 
voltages as may be caused by lightning. The apparatus includes a plurality 
of manually operated switches which may be connected for common operation. 
Accordingly, a user may manually switch the connections to isolate the 
equipment side conductors from the line and connect them to the chassis 
ground for protection. Unfortunately, the user must still remember and 
take the time to manually operate the switches prior to and after each 
use. 
By way of further example, U.S. Pat. No. 4,276,576 to Uman et al. is 
directed to lightning protection of electronic or electrical equipment 
wherein the electronic equipment is moved to a protected state responsive 
to detection of nearby lightning or detection of a power outage. U.S. Pat. 
No. 5,291,208 to the present inventor, and assigned to the assignee of the 
present invention, describes a significant improvement in the area of 
lightning detection and equipment protection. These types of protection 
devices must first detect lightning or another disturbance before moving 
the electronic equipment to a protected state. Accordingly, accuracy and 
speed of detection are desirably combined with rapid switching to protect 
the equipment against lightning related disturbances. 
SUMMARY OF INVENTION 
In view of the foregoing background, it is therefore an object of the 
invention to provide an apparatus and associated method for protecting 
electrical and electronic equipment against potentially damaging 
disturbances carried to the equipment by external electrical conductors. 
This and other objects, advantages and features of the present invention 
are provided by a protection apparatus for protecting electrical and 
electronic equipment comprising switching means being switchable between a 
protected state and an operating state; power consumption sensing means 
for sensing electrical power consumption of the electrical equipment; and 
control means for permitting a user to switch the switching means to the 
operating state, and for switching the switching means to the protected 
state responsive to sensed power consumption of the electrical equipment 
indicating nonuse thereof. Accordingly, the apparatus protects the 
electrical equipment from disturbances carried by the external electrical 
conductors when the electrical equipment is not in use. For simplicity, 
the term electrical equipment is used to refer to both sensitive 
electronic equipment, as well as electrical equipment having little or no 
electronics. 
In particular, the switching means when in the protected state isolates 
equipment sides of the external electrical conductors from respective line 
sides of the external electrical conductors. Conversely, the switching 
means when in the operating state connects line sides of the external 
electrical conductors to respective equipment sides of the external 
electrical conductors. The apparatus preferably includes a housing which 
also serves to mount a plurality of electrical connectors for interfacing 
with the electrical equipment and downstream external conductors. For 
example, the plurality of electrical connectors may comprise at least one 
of an AC power connector, a DC power connector, a coaxial cable connector, 
a telephone line connector, and a data connector. 
In one embodiment, the apparatus also preferably includes lightning sensing 
means for switching the switching means to the protected state responsive 
to sensing of lightning. Alternately, or in addition, the apparatus may 
also include power loss sensing means for sensing a loss of power from the 
power source and for switching the switching means immediately to the 
protected state responsive to sensing a loss of power. In other words, 
protection is provided against other events or occurrences capable of 
causing a potentially damaging surge or disturbance to be carried by the 
external conductors to the electrical equipment. 
Another aspect of the invention is that the switching means preferably 
comprises shunting means for shunting equipment sides of the external 
conductors together in the protected state. In one embodiment, the 
switching means may comprise ground isolating means for isolating shunted 
equipment sides of the external conductors from an external ground 
electrical conductor. Accordingly, the equipment is protected from the 
particularly troublesome ground potential rise that would otherwise be 
carried to the equipment via the ground conductor. In another embodiment, 
the switching means further comprises ground connecting means for 
connecting shunted equipment sides of the external electrical conductors 
to the external ground electrical conductor. 
The control means also preferably includes start-up timer means for 
switching the switching means to the protected state a predetermined time 
after the switching means is initially switched to the operating state and 
responsive to sensed power consumption indicating that the electrical 
equipment has not yet been turned on thus defining a start-up operating 
state for the protection apparatus. Accordingly, the user has sufficient 
time to turn on the electrical equipment, but if he forgets or fails to do 
so, the apparatus will time out and switch to the protected state. 
Start-up indicator means may be provided for indicating to the user whether 
the protection apparatus is in the start-up operating state. In addition, 
state indicator means may be carried by the housing for providing an 
indication of whether the switching means is in the protected state or the 
operating state. 
The protection apparatus may be initially moved to the operating state in 
several different ways. For example, the control means may comprise a 
manually operable switch carried by the housing for permitting a user to 
initially switch the switching means to the operating state. Alternately, 
or in addition thereto, a remote control unit may be carried by the user. 
Accordingly, the control means thus preferably further comprises a 
receiver for receiving a signal from the remote control unit for 
permitting the user to initially switch the switching means to the 
operating state. The remote control unit may preferably be a wireless hand 
held transmitter of the type as commonly used for the control of home 
entertainment equipment, for example. 
The power consumption sensing means may be an electrical current sensor 
coupled to the external electrical connectors providing power to the 
electrical equipment from the electrical power source. In addition, the 
electrical current sensor may be provided in part by a toroidal coil 
coupled to the AC power line. 
A method aspect of the present invention is for protecting electrical 
equipment from an electrical disturbance carried by external electrical 
conductors connecting the electrical equipment to at least a source of 
electrical power. The method preferably comprises electrically connecting 
switching means to the external electrical conductors with the switching 
means being switchable between a protected state and an operating state. 
The switching means when in the protected state isolates equipment sides 
of the external electrical conductors from respective line sides of the 
external electrical conductors, and when in the operating state connects 
line sides of the external electrical conductors to respective equipment 
sides of the external electrical conductors. 
The method also preferably includes the steps of sensing electrical power 
consumption of the electrical equipment, permitting a user to initially 
switch the switching means to the operating state, and switching the 
switching means to the protected state responsive to sensed power 
consumption of the electrical equipment indicating nonuse thereof. 
Accordingly, the electrical equipment is protected from disturbances 
carried by the external electrical conductors when the electrical 
equipment is not in use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will now be described more fully hereinafter with 
reference to the accompanying drawings, in which preferred embodiments of 
the invention are shown. This invention may, however, be embodied in many 
different forms and should not be construed as limited the embodiments set 
forth herein. Rather, these embodiments are provided so that this 
disclosure will be thorough and complete, and will fully convey the scope 
of the invention to those skilled in the art. Like numbers refer to like 
elements throughout. 
Referring now initially to FIGS. 1-3, an electrical equipment protection 
apparatus 10 in accordance with the present invention is first described. 
The protection apparatus 10 comprises a housing 12 for containing the 
components and for mounting a plurality of electrical connectors 14 which, 
in turn, establish connections to the line side 16 and equipment side 18 
of various external electrical conductors. Such external electrical 
conductors are commonly used for electrical equipment 20, such as the 
illustrated personal computer 11 and television receiver 13, for example, 
as would be readily understood by those skilled in the art. 
Referring more particularly to FIG. 3, a power use or power consumption 
sensor 22 is positioned within the housing 12 for sensing power 
consumption of the electrical equipment 20. Power consumption by the 
electrical equipment 20 indicates that the equipment is in use, while if 
the power consumption sensed were zero, the equipment would typically not 
be in use and would be turned off. Switching means provided by the 
schematically illustrated switcher 24 is also positioned within the 
housing 12 and is responsive to the power consumption sensor 22. The 
switcher 24 connects line sides of the external conductors 16 to equipment 
sides of the external conductors 18 when the apparatus 10 is in the 
operating mode. Accordingly, power and other connections are established 
and maintained to operate the electrical equipment 20 when in the 
operating mode. 
When sensed power consumption indicates that the electrical equipment 20 is 
not being used, the switcher 24 disconnects the line and equipment sides 
of the external conductors so that the apparatus 10 is in a protected 
state or mode with the electrical equipment being isolated to the external 
conductors. Accordingly, electrical disturbances or surges, such as from 
lightning or power system faults, cannot be coupled from the electrical 
equipment 20 via the external conductors. 
The electrical equipment 20 may be powered from the protection apparatus 10 
through the illustrated AC power cord 16A. In addition, coaxial connectors 
16B, and modem and telephone jacks 16C, and/or a DC connector 16D may also 
be provided, carried by the housing 12, and operatively coupled to the 
switcher 24. 
To initially switch the apparatus 10 to the operating mode a timer 26 is 
initially triggered by depressing the manually operable switch 28, for 
example. The timer 26 maintains the switcher 24 in the operating state 
even though the electrical equipment 20 has not yet been turned on, and, 
hence, the current or power sensor 22 is not yet indicating power flow. In 
other words, the timer 26 defines a start-up operating state for the 
apparatus. In an alternate embodiment of the invention, a remote infrared 
transmitter 30 is used to activate the timer 26 through the illustrated 
infrared receiver 32 which includes an optical detector 29. Infrared 
remote control transmitters and receivers are widely used in the area of 
house entertainment component control, as would be readily understood by 
those skilled in the art. As would also be readily understood by those 
skilled in the art, other types of wired or wireless remote transmitters 
may also be used in accordance with the invention. 
A first or start-up state LED 34 lights alerting the user, and the user 
must turn on the connected equipment 20 before the timer 26 times out and 
the apparatus 10 moves to the protected state with the equipment 20 being 
disconnected. The timer 26 is typically set for about thirty seconds. Once 
the equipment 20 is powered up, a second or state indicating LED 36 may be 
illuminated to indicate the apparatus is in the operating state. The 
length of the time period may be set by a potentiometer 68 (FIGS. 1 and 
5). The power consumption sensor 22, monitors power used by the equipment. 
If the electrical equipment 20 is turned off, the power sensor 22 will 
cause the switcher 24 to disconnect the equipment 20. Accordingly, the 
equipment 20 is protected from potential surges when not in use. 
As illustrated with reference to FIG. 4 another aspect of the invention is 
that the switcher 24 desirably immediately moves to the protected state 
based upon a loss of power, such as typically delivered via the AC power 
conductors. In other words, the switcher 24 may comprise a relay coil 
which drops the relay upon a loss of power supplied to the apparatus 10. 
Accordingly, the electrical equipment 20 is protected against any surges 
as may be caused, for example, as an automatic recloser on the utility 
power system attempts to clear a fault by periodically closing the 
substation breaker for the faulted line. 
Yet another aspect of the invention is that the equipment side of all three 
AC power conductors, hot 38A, neutral 38B, and ground 38C are isolated 
from the line side, and the equipment side of the external conductors are 
shunted together. Conventional protection schemes typically ground all 
equipment side conductors. However, it has been found that it may be more 
desirable to leave the equipment conductors floating, or more preferably, 
to leave the conductors floating and shunt them together as illustrated, 
by way of example, with reference to FIG. 4. The equipment side of the 
other external electrical conductors may also be isolated from their 
respective line sides. Similarly, the equipment sides may be shunted 
together and left floating from ground. This reduces a likelihood of 
damage due to a low side surge that is not addressed by conventional 
protection devices, such as those using an MOV or gas discharge tubes, 
since these are ground referenced devices. 
In other embodiments of the invention, it may be desirable to connect all 
of the shunted together line sides to an earth ground as would be readily 
understood by those skilled in the art. 
As further illustrated with reference to FIG. 4, the switcher 24 may be 
driven by a lightning sensor 40 that will also cause the switcher to 
isolate and shunt together the equipment input and output lines 16, 18 
upon the sensing or detection of lightning. For example, U.S. Pat. No. 
5,291,208 to the present inventor, and assigned to the assignee of the 
present invention, describes a receiver and its associated circuitry 
suitable for detecting the nearby presence of potentially damaging 
lightning, and the entire disclosure of this patent is incorporated herein 
by reference in its entirety. Accordingly, the electrical equipment 20 may 
enjoy yet a further degree of protection from damage based upon nearby 
lightning causing disturbances or surges on the external electrical 
conductors. The timer 26, receiver 32, and switch 28 along with associated 
circuitry described below define control means for moving the switcher 24 
between protected and operating states. 
Turning now to the circuit schematic diagram of FIG. 5, the apparatus 10 is 
further described and illustrated in a protected state or mode. A source 
of AC power is supplied via the power connections 38 as earlier described 
with reference to FIG. 4 and delivers AC power via conductors 42 to the 
electrical equipment 20. The source power is supplied or disconnected via 
relay RY1 designated as numeral 44 which in the preferred embodiment is a 
3PDT relay. The relay 44 disconnects and isolates the electrical equipment 
20 connected through the power connections 38. Further, this relay 
isolates the equipment 20 from ground 38C to prevent damage from low side 
surges, in other words, surges that are predominantly present on the 
ground conductor 38C, typically from nearby lightning strikes being 
dissipated into the earth and conducted to equipment ground connections. 
As further illustrated with reference to FIG. 5, the protected AC power 42 
to the electrical equipment 20 is isolated from the source 38 and lines 
shunted together to prevent a surge from entering the equipment should the 
surge arc across a contact gap in the relay 44 when in the protected mode. 
When in this protected mode, a switch SW1, identified by numeral 46 
provides an option of placing the equipment power input 42 at ground 
potential in addition to isolating and shunting. Again, should the surge 
jump the gap of the relay 44, the surge would be directed to ground and 
not to the electrical equipment 20. In typical operation, equipment 
electrical ground continuity is maintained for safety purposes. 
The same methodology of protecting equipment from surges in the power 
conductors or lines is used for signal lines by the disconnecting, 
shunting, and/or grounding the external conductors coupled via coax 
connectors 16B, 18B, telephone and/or data connectors 16C, 18C, and other 
external conductors in general. When AC power is disconnected, shunting 
and grounding as earlier described for power are performed for the signal 
lines in a similar manner using relays RY4 and RY5, identified with 
numerals 48 and 50, respectively. 
Commercial and industrial configurations may be desirable where equipment 
or components are powered by a DC power source operated in conjunction 
with the AC powered equipment, such as is in remote located switching and 
isolating relays. Such a configuration may also benefit from protection 
provided by the apparatus 10 in accordance with the invention as would be 
readily understood by those skilled in the art. The relay RY3, numeral 52, 
provides for such protection where a DC power source is disconnected, 
isolated, and the equipment side conductors are shunted together to 
ground, simultaneously with the AC power and other electrical conductors. 
In one embodiment of the present invention, provision is made for an 
external DC power supply via SW3, numeral 54, in the event the internal 
power supply of the apparatus 10 does not offer the required voltage or 
current needed. In operation, the electrical equipment 20 is connected to 
the apparatus 10, as earlier described; switch SW2, numeral 28, is 
manually operated or remotely controlled, also as earlier described via 
remote transmission methods. Normally open contacts as illustrated with 
reference to those described in FIG. 5, are momentarily closed, at which 
time capacitor C4, numeral 58, is charged causing transistor Q2, numeral 
60, to be forward biased. This in turn provides a coil voltage for relays 
44, 48, 50, and 52, which connects the equipment 20 to all external 
electrical conductors or lines (AC & DC power, coax, telephone, data, 
control, and any others incorporated into the apparatus) and is indicated 
by an illuminated LED1, numeral 34. 
At this point, the electrical equipment 20 is normally turned on for use, 
and the current draw from the AC power source, or the power consumption of 
the equipment, is detected, in part, by the toroid transformer T2, numeral 
60. The output of the toroid transformer 60 is proportional to the amount 
of current drawn and is applied to an amplifier 62 which is rectified via 
circuit 64, and which DC voltage is then applied to the base of transistor 
Q1, numeral 66. When the voltage adjusted via resistor R3, numeral 69, is 
applied to the base of the transistor Q1, numeral 66, indicating that the 
equipment is consuming power, the transistor Q1, is forward biased and 
relay RY2, numeral 67, is activated, as indicated by LED2 36. 
All equipment electrical connections are maintained in the operating 
position (by the second set of contacts of relay RY2 67) as long as 
current is sensed by the toroid transformer 60. This condition will remain 
until the equipment 20 is turned off and current is no longer being drawn, 
at which time, the relays, as herein described, will automatically switch, 
disconnecting and isolating electrical connections to some or all external 
electrical conductors. 
As further described with reference to FIG. 5, the apparatus 10 of the 
present invention has additional built-in safeguards. If equipment 20 is 
operating and the AC power source is lost, the relays drop out and revert 
to the disconnected and isolated positions, thus further protecting the 
equipment 20. In addition, if the switch SW2 28 or the remote controlled 
normally opened contacts are momentarily closed, but the equipment is not 
turned on within the predetermined time of approximately thirty seconds, 
the time constant of R2-C4 circuit 65 will be exceeded and the transistor 
Q2 61 will no longer be forward biased, thus causing the relays again to 
drop out and revert to the disconnected or protected state. This situation 
is particularly valuable where the apparatus 10 was either accidentally 
activated and the user was not planning to use the equipment, or if the 
apparatus was activated but the user was interrupted or distracted, thus 
exposing the electrical equipment 20 to possible damage. 
The apparatus 10 in a preferred embodiment herein described provides a 
level of on-line protection through the three metal oxide varistors 
(MOV's) arranged in a preferred common-mode configuration 70, wherein 
noise on the AC line is filtered and attenuated by capacitor C1, prior to 
being applied to the electrical equipment 20. The apparatus 10 thus 
provides protection to equipment 20 such as a personal computer, by 
controlling the AC power and modem telephone line connections 16C, 18C. 
The apparatus 10 may also be used in a more complex setting in the home 
where an entertainment system includes AC power, coax and control 
connections for a TV, am-fm receivers, VCR and CATV or even a satellite 
receiving system when the equipment is powered-up, but isolates the lines 
to the equipment 20 when the equipment 20 is not in operation. 
Accordingly, many modifications and other embodiments of the invention 
will come to the mind of one skilled in the art having the benefit of the 
teachings presented in the foregoing descriptions and the associated 
drawings. Therefore, it is to be understood that the invention is not to 
be limited to the specific embodiments disclosed, and that modifications 
and embodiments are intended to be included within the scope of the 
appended claims.