Resistor dropper power supply with surge protection
View Patent ↗A power supply system and corresponding methodology is provided for providing a self-protected power supply for use with electronic electricity meters. The self-protecting features are provided, in part, through the use of surface mounted resistive components corresponding to a resistor dropper portion of the power supply. The use of surface mount components also provides a general reduction in circuit board surface area requirements thereby providing a compact overall construction and provides economies with respect to reduction in manufacturing process steps. When the surface mount resistor divider is configured along with a half-wave rectifier, a low voltage DC supply is obtained from a direct connection to a much higher voltage AC mains source without requiring the use of coupling capacitors or transformers. Plural output voltages may be provided and capacitive filtering may be associated with the outputs. The use of a surface mount resistor divider in combination with surge protection elements helps to distribute any power surge over the power supply, which facilitates the use of less robust surge protection devices to achieve desired levels of protection.
1. A self-protected power supply, comprising:
a resistor dropper portion;
a half-wave rectifier portion operatively associated with said resistor dropper portion; and
a voltage clamp portion;
wherein said resistor dropper portion includes
n series connected groups of resistors, and
n resistors connected in parallel within each of said groups of resistors;
wherein n≧2; and
wherein said half-wave rectifier portion is connected in series between selected of the n series connected groups of resistors.
2. A self-protected power supply as in claim 1 , further comprising:
a capacitor portion; and
wherein said capacitor portion is coupled in parallel with said voltage clamp portion.
3. A self-protected power supply as in claim 2 , further comprising:
a voltage regulator portion, having an input portion and an output portion; and
wherein said input portion of said voltage regulator portion is coupled to said capacitor portion.
4. A self-protected power supply as in claim 1 , wherein said half-wave rectifier portion comprises a pair of diodes connected in series.
5. A self-protected power supply as in claim 4 , further comprising:
a pair of series connected resistors for equalization coupled in parallel with said pair of diodes.
6. A self-protected power supply as in claim 1 , wherein said n resistors connected in parallel within each of said groups of resistors of said resistor dropper portion comprises surface mount resistors.
7. A self-protected power supply as in claim 1 , wherein each of said n resistors within each of said n series connected group of resistors has substantially the same resistive value.
8. A self-protected power supply as in claim 1 , wherein said voltage clamp portion includes a Zener diode.
9. A power supply system for providing a self-protected power supply for use with electronic electricity meters, comprising:
a resistor dropper portion comprising a plurality of surface mounted resistive components, said resistor dropper portion having an input thereto associated with an AC mains which in turn is associated with an electronic electricity meter with which said power supply is used;
a half-wave rectifier portion connected in series between portions of the plurality of surface mounted resistive components of said resistor dropper portion for providing a DC voltage output having a relatively lower voltage than the voltage of the associated AC mains; and
a surge protection portion, operatively interposed between the associated AC mains and said resistor dropper portion;
whereby any power surge is relatively distributed over said power supply system to achieve desired levels of protection for the associated electronic electricity meter while a relatively lower voltage DC supply is obtained from a direct connection to a much higher voltage AC mains source without requiring the use of coupling capacitors or transformers, while also providing a general reduction in circuit board surface area requirements thereby resulting in a relatively compact overall construction.
10. A power supply system as in claim 9 , further including a voltage regulator portion, operatively interposed between said half-wave rectifier portion and an associated electronic electricity meter.
11. A power supply system as in claim 9 , wherein:
said resistor dropper portion comprises n series connected groups of
resistors, and n resistors connected in parallel within each of said groups of
resistors; and
wherein n≧2.
12. A self-protected power supply as in claim 11 , wherein each of said n resistors within each of said n series connected group of resistors has substantially the same resistive value.
13. A method for providing a self-protected power supply for use with electronic electricity meters, comprising the steps of:
connecting a first predetermined number of surface mount resistors in parallel with a common input thereto;
connecting a second predetermined number of surface mount resistors in parallel to a common output thereto; and
connecting a half-wave rectifier in series between said first predetermined number of surface mount resistors and said second predetermined number of surface mount resistors,
whereby a relatively higher AC voltage source associated with said common input to said first predetermined number of surface mount resistors may be reduced to a relatively lower voltage DC voltage for supplying the electronics of an electronic electricity meter associated with the self-directed power supply.
14. A method as in claim 13 , further comprising the step of:
selecting the number of said first predetermined number of surface mount resistors to be equal to the number of said second predetermined number of surface mount resistors.
15. A method as in claim 13 , further comprising the step of:
selecting the resistive value of said first predetermined number of surface mount resistors to be substantially the same resistive value as that of said second predetermined number of surface mount resistors.
16. A method as in claim 14 , further comprising the steps of:
operatively connecting a voltage clamp with said second predetermined number of surface mount resistors; and
connecting a storage capacitor in parallel with said voltage clamp.
17. A method as in claim 16 , further comprising the step of:
connecting a voltage regulator to said common output associated with second predetermined number of surface mount resistors.
18. A method as in claim 13 , wherein said step of connecting a half-wave rectifier in series between said first predetermined number of surface mount resistors and said second predetermined number of surface mount resistors comprises connecting a pair of series connected diodes between said respective first and second predetermined number of surface mount resistors.
19. A method as in claim 18 , further comprising the step of connecting a pair of series connected resistors in parallel with said pair of series connected diodes.
20. A method for providing a self-protected power supply for an electronic metrology device, comprising the steps of:
providing a surge protective device configured for connection to a power mains supply with which the electronic metrology device is associated;
connecting a first predetermined number of surface mount resistors in parallel;
connecting a second predetermined number of surface mount resistors in parallel;
connecting a half-wave rectifier in series between said first predetermined number of surface mount resistors and said second predetermined number of surface mount resistors;
operatively interconnecting said first predetermined number of surface mount resistors with said surge protective device; and
connecting a voltage regulator configured for connection to an associated electronic metrology device, the electronics of which is to be powered by the self-protected power supply while the electronic metrology device determines measurements based on the power mains supply.
21. A method as in claim 20 , further comprising the step of:
selecting the first predetermined number to be equal to the second predetermined number.
22. A method as in claim 21 , further comprising the step of:
selecting the resistive values of said surface mount resistors in dependence on selected characteristics of the power mains supply and the electronic metrology device.
23. A method as in claim 20 , wherein said step of connecting a half-wave rectifier in series between said first predetermined number of surface mount resistors and said second predetermined number of surface mount resistors comprises connecting comprises connecting a pair of series connected diodes between said respective first and second predetermined number of surface mount resistors.
24. A method as in claim 23 , further comprising the step of connecting a pair of series connected resistors in parallel with said pair of series connected diodes.
25. A method as in claim 23 , further comprising the steps of:
operatively interconnecting a voltage clamp with said second perdetermined number of surface mount resistors; and
connecting a storage capacitor in parallel with said voltage clamp.