Shock proof devices and methods

Abstract

Devices and methods for preventing shock from a high voltage power source. In one embodiment, a device for preventing an electric shock, comprises output terminals for connecting to an external load, a low voltage circuit for carrying a first current (I L ) to the output terminals, the low voltage circuit comprising a first coil disposed about a magnetic core, and a high voltage circuit for carrying a second current (I H ) to the output terminals, the high voltage circuit comprising a second coil disposed about the magnetic core, and a control relay configured to electrically connect one of the high voltage circuit and the low voltage circuit to the output terminals based at least partly on the first current (I L ).

1 . An electrical safety device for preventing electrical shock, the device comprising:
 means for receiving power from a high voltage source;   output terminals connectable to an external electrical load;   means for providing a low voltage current (I L ) to the output terminals;   means for providing a high voltage current (I H ) to the output terminals;   means for selectively providing power from one of the low voltage current providing means and the high voltage current providing means to the output terminals; and   wherein the means for selectively providing power includes a default state and an energized state, wherein low voltage is provided in the default state and high voltage is provided in the energized state; and   wherein the means for selectively providing power remains in the energized state while a magnetic field produced due to the I H  current flowing in the means for selectively providing power equals or exceeds a threshold magnetic field.   
     
     
         2 . The device of  claim 1 , wherein the means for selectively providing power comprises a low voltage coil configured to carry the I L  current and a high voltage coil configured to carry the I H  current, and wherein the magnetic field is produced due to the I H  current flowing in the high voltage coil of the means for selectively providing power. 
     
     
         3 . The device of  claim 1 , wherein the receiving power means comprises high voltage input terminals. 
     
     
         4 . The device of  claim 1 , wherein the receiving power means comprises high voltage input terminals. 
     
     
         5 . The device of  claim 1 , wherein the low voltage current (I L ) providing means comprises:
 a low voltage source configured to produce low voltage from power received from the high voltage source; and   a low voltage circuit for carrying the first current (I L ) to the output terminals, the low voltage circuit comprising a first coil disposed about a magnetic core of the means for selectively providing power.   
     
     
         6 . The device of  claim 5 , wherein the current (I H ) providing means comprises a high voltage circuit for carrying the high voltage current (I H ) to the output terminals, wherein the high voltage circuit comprising a second coil disposed about the magnetic core. 
     
     
         7 . The device of  claim 1 , wherein the low voltage current (I L ) providing means is a voltage source configured to provide a low DC voltage in the range between 1 mV to about 30 V. 
     
     
         8 . The device of  claim 1 , wherein the high voltage current (I H ) providing means provides an AC voltage in the range of about 30 Vrms to about 500 Vrms. 
     
     
         9 . The device of  claim 1 , wherein the high voltage current (I H ) providing means provides an AC voltage in the range of about 500 Vrms to about 10,000 Vrms. 
     
     
         10 . The device of  claim 1 , wherein the low voltage current (I L ) providing means is a voltage source configured to provide a low AC voltage in the range between 1 mVrms to about 30 Vrms. 
     
     
         11 . The device of  claim 1 , wherein the magnetic field exceeds the threshold magnetic field when a magnitude of the I L  current equals or exceeds a low voltage current threshold value. 
     
     
         12 . The device of  claim 11 , wherein the magnitude of the I L  current equals or exceeds a low voltage current threshold value when an external electrical load having a load impedance (Z L ) that is less than a threshold impedance is connected to the power outlet. 
     
     
         13 . The device of  claim 12 , wherein the threshold impedance is between about 500 Ω and about 10 kΩ. 
     
     
         14 . The device of  claim 13 , wherein the threshold impedance is between about 10 kΩ and about 100 kΩ. 
     
     
         15 . The device of  claim 1 , wherein the means for selectively providing power comprises:
 a high voltage coil;   a low voltage coil;   a magnetic core that is disposed within the high voltage coil and the low voltage coil;   a lever system comprising a support frame disposed with respect to at least one of the low voltage coil and the high voltage coil,   a pivot connected to the support frame;   a metallic strip rotatably connected to the pivot, the metallic strip having a first side and a second side, and   a common contact disposed on the metallic strip;   a high voltage contact disposed on the first side of the metallic strip; and   a low voltage contact disposed on the second side of the metallic strip, wherein the pivot comprises a spring that is configured to apply a torque on the metallic strip such that the common contact makes an electrical contact with the low voltage contact in the default state.   
     
     
         16 . A method of preventing an electrical shock in a device having input terminals to receive power from a high voltage source and output terminals to connect to an electrical load and provide power to the electrical load, the method comprising:
 receiving high voltage power in a high voltage circuit from a high voltage source connected to the input terminals;   generating a low voltage current (I L ) from the high voltage power received from the high voltage source;   connecting the low voltage circuit to the output terminals to provide the low voltage current (I L ) to an electrical load connected to the output terminals; and   changing a control relay from a default state to an energized state to selectively connect the high voltage circuit to the output terminals to provide a high voltage current (I H ) to an electrical load connected to the output terminals, wherein connecting the high voltage circuit is based at least partly on the flow of the low voltage current (I L ) through the control relay,   wherein the control relay connects the low voltage circuit to the output terminals in the default state and connects the high voltage circuit to the output terminals in the energized state, the control relay configured to switch from the default state to the energized state when a magnetic field produced by the I L  current flowing in a first coil surrounding a core of the control relay equals or exceeds a threshold magnetic field, and wherein the control relay is configured to remain in the energized state while a magnetic field produced by the I H  current flowing in a second coil surrounding the core equals or exceeds a threshold magnetic field.   
     
     
         17 . The method of  claim 16 , wherein the magnetic field exceeds the threshold magnetic field when the magnitude of the I L  current equals or exceeds a low voltage current threshold value. 
     
     
         18 . The method of  claim 17 , wherein the magnitude of the I L  current equals or exceeds a low voltage current threshold value when an external electrical load having a load impedance (Z L ) that is less than a threshold impedance is connected to the power outlet. 
     
     
         19 . The method of  claim 18 , wherein the threshold impedance is between about 500 Ω and about 10 kΩ. 
     
     
         20 . The method of  claim 18 , wherein the threshold impedance is between about 10 kΩ and about 100 kΩ.