Electrical over/under voltage automatic disconnect apparatus and method
A method for providing an analog or digital circuit that senses both low and high input voltage and operates to disconnect both line and neutral electrical power connections to a protected device when abnormally low or high voltages are received from a single- or multi-phase power source, and reconnects the protected device when input power has stabilized. The sensing circuit and power supply is functional with voltages up to at least 240 Vac. The nominal 120 Vac circuit is designed to withstand a 6 kilovolt surge without damage. The method does not disconnect the ground line during an out-of-tolerance voltage condition.
1. A method of providing electrical over/under voltage protection comprising:
a. providing a connecting means for connecting to a supply of at least one phase of alternating current power having a line, neutral and ground;
b. providing a sensing means for sensing the voltage of the supplied power, wherein the sensing means detects voltage differences between the following lines:
i. line and neutral;
ii. line and ground; or
iii. neutral and ground;
c. determining whether the voltage is within an acceptable voltage range across at least 2 of the preceding lines;
d. providing a power surge absorption means;
e. providing a distribution means having a corresponding line, neutral and ground for distributing the sensed power;
f. providing a disconnecting means for disconnecting the distribution means line and neutral from the power source when the sensing means detects an out-of-tolerance voltage condition across the line-neutral, or line-ground, wherein the sensing means activates the disconnecting means before the apparatus suffers electrical damage;
g. a reconnecting means for reconnecting the sensed power to the distribution means when the sensing means no longer detects an out-of-tolerance voltage condition; and
h. wherein detection of the out-of-tolerance voltage condition comprises detection of a voltage of less than approximately 60 Vrms and greater than approximately 132 Vrms.
2. The method in accordance with claim 1 wherein providing a sensing means comprises selecting a sensing means selected from a group comprising analog devices and digital devices.
3. The method in accordance with claim 2 wherein the sensing means detects voltages in excess of 132 Vrms.
4. The method in accordance with claim 1 wherein the distribution means distributes power through at least one three-prong electrical outlet receptacle.
5. The method of claim 1 wherein the reconnecting means activates after a delay of approximately 15 seconds from when the sensing means no longer detects an out-of-tolerance voltage condition.