Two wire air gap off power supply

A power supply circuit for selectively connecting and disconnecting a load from an alternating current power source having neutral and line conductors, said load being connected to said neutral conductor and to said power supply circuit via a load conductor, said power supply circuit comprising:

• a transformer having a primary winding connected to said load and a secondary winding;
• a relay connected at one terminal thereof to said primary winding and connected at another terminal thereof to one of said line conductor and said load conductor;
• a control circuit connected to said relay and operable to open and close said relay, said relay being operable to complete and interrupt a current path along said line conductor, said primary winding and said load conductor when closed and open, respectively;
• a first rectifier circuit connected in parallel with said secondary winding;
• a resistor connected to said first rectifier circuit;
• a capacitor connected to said resistor;
• a switch connected in parallel with said resistor and having substantially less impedance when closed than said resistor;
• and
• a processor circuit to selectively close said switch to generate a pulse signal to charge said capacitor.

A power supply circuit for selectively connecting and disconnecting a load from an alternating current power source having neutral and line conductors, said load being connected to said neutral conductor and to said power supply circuit via a load conductor, said power supply circuit comprising:

• a transformer having a primary winding connected to said load and a secondary winding;
• a relay connected at one terminal thereof to said primary winding and connected at another terminal thereof to one of said line conductor and said load conductor;
• a control circuit connected to said relay and operable to open and close said relay, said relay being operable to complete and interrupt a current path along said line conductor, said primary winding and said load conductor when closed and open, respectively;
• a first rectifier circuit connected in parallel with said relay;
• and
• a second rectifier circuit connected in parallel with said secondary winding.

A power supply circuit for selectively connecting and disconnecting a load from an alternating current power source having neutral and line conductors, said load being connected to said neutral conductor and to said power supply circuit via a load conductor, said power supply circuit comprising:

• a transformer having a primary winding connected to said load and a secondary winding;
• a relay connected at one terminal thereof to said line conductor and connected at another terminal thereof to said primary winding when closed and to said secondary winding when open;
• and
• a first rectifier circuit connected in parallel with said secondary winding.

A power supply circuit for selectively connecting and disconnecting a load from an alternating current power source having neutral and line conductors, said load being connected to said neutral conductor and to said power supply circuit via a load conductor, said power supply circuit comprising:

• a transformer having a primary winding connected to said load via a load conductor and a secondary winding;
• a relay connected at one terminal thereof to said primary winding and connected at another terminal thereof to said line conductor;
• a control circuit connected to said relay and operable to open and close said relay, said relay being operable to provide power to said load when closed and to disconnect at least one of said line conductor and said load conductor from said primary winding when open;
• a first rectifier circuit connected in parallel with said secondary winding;
• and
• an air gap switching mechanism connected to said relay and said control circuit, said control circuit being operable to detect a change in voltage across said secondary winding when said air gap switching mechanism is activated and to open said relay.

A power supply circuit for selectively connecting and disconnecting a load from an alternating current power source having neutral and line conductors, said load being connected to said neutral conductor and to said power supply circuit via a load conductor, said power supply circuit comprising:

• a transformer having a primary winding connected to said load and a secondary winding;
• a relay connected at one terminal thereof to said primary winding and connected at another terminal thereof to one of said line conductor and said load conductor;
• a control circuit connected to said relay and operable to open and close said relay, said relay being operable to complete and interrupt a current path along said line conductor, said primary winding and said load conductor when closed and open, respectively;
• a first rectifier circuit connected in parallel with said secondary winding;
• an air gap switching mechanism connected to said control circuit and operable to open said relay when said air gap switching mechanism is activated, said control circuit comprising a processor circuit and an air gap detection circuit connected to said processor circuit, said air gap switching mechanism comprising a switch in series with said secondary winding and operable to connect and disconnect said air gap detection circuit to and from said secondary winding when switched to first and second positions, respectively.

A power supply circuit for selectively connecting and disconnecting a load from an alternating current power source having neutral and line conductors, said load being connected to said neutral conductor and to said power supply circuit via a load conductor, said power supply circuit comprising:

• a transformer having a primary winding connected to said load and a secondary winding;
• a relay connected at one terminal thereof to said primary winding and connected at another terminal thereof to one of said line conductor and said load conductor;
• a control circuit connected to said relay and operable to open and close said relay, said relay being operable to complete and interrupt a current path along said line conductor, said primary winding and said load conductor when closed and open, respectively;
• a first rectifier circuit connected in parallel with said secondary winding;
• an air gap switching mechanism connected to said control circuit and operable to open said relay when said air gap switching mechanism is activated, said control circuit comprising a processor circuit and an air gap detection circuit connected to said processor circuit, said air gap switching mechanism comprising a switch having a first set of contacts connected in series with said transformer, said transformer and said first set of contacts being connected in parallel with said first rectifier circuit, and a second set of contacts connected to said air gap detection circuit, said switch being operable to disconnect said transformer from said first rectifier circuit when said switch is in a first position, said air gap detection circuit being operable to detect a decrease in voltage and said processor circuit being operable to open said relay in response thereto.

A power supply circuit for selectively connecting and disconnecting a load from an alternating current power source having neutral and line conductors, said load being connected to said neutral conductor and to said power supply circuit via a load conductor, said power supply circuit comprising:

• a transformer having a primary winding connected to said load and a secondary winding;
• a relay connected at one terminal thereof to said primary winding and connected at another terminal thereof to one of said line conductor and said load conductor;
• a control circuit connected to said relay and operable to open and close said relay, said relay being operable to complete and interrupt a current path along said line conductor, said primary winding and said load conductor when closed and open, respectively;
• a first rectifier circuit connected in parallel with said secondary winding;
• an air gap switching mechanism connected to said control circuit and operable to open said relay when said air gap switching mechanism is activated, said air gap switching mechanism comprising a switch in series with said secondary winding and being operable to connect and disconnect said first rectifier circuit to and from said secondary winding when closed and opened, respectively, and said control circuit being operable to detect a decrease in voltage and open said relay in response thereto.