Ballast for fluorescent emergency lighting

• US 8,629,574 B2
• Filed: 08/18/2010
• Issued: 01/14/2014
• Est. Priority Date: 08/18/2009
• Status: Expired due to Fees

• Current Assignee: Cooper Technologies Company (Eaton Corporation PLC.)
• Original Assignee: Cooper Technologies Company (Eaton Corporation PLC.)
• Inventors: Porter, Kevin, Mangiaracina, Anthony
• Primary Examiner(s): CAVALLARI, DANIEL J
• Application Number:
  US12/859,012
• Publication Number:
  US 20110043040A1
• Time in Patent Office: 1,245 Days
• Field of Search: 307/66, 315/86
• US Class Current: 307/66
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02J 9/02 in which an auxiliary distribution system and its associated lamps are brought into service
• CPC Class Codes: H05B 41/2985 against abnormal lamp operating conditions

Abstract

An emergency ballast for a fluorescent lamp includes a rechargeable battery. The emergency ballast also includes a circuit for receiving an electrical voltage and providing a recommended charging voltage to the battery. The electrical voltage is one of two amplitudes, and the circuit provides a charge to the battery without regard to the amplitude of the electrical voltage. The first amplitude of the electrical voltage can be 120 volts, and the second amplitude can be 277 volts. The emergency ballast includes a capacitor electrically coupled to the circuit that provides an additional voltage to the rechargeable battery when the electrical current is 120 volts. The emergency ballast also includes a switch for electrically decoupling the capacitor from the circuit when the electrical current is 277 volts.

Claims

1. An emergency ballast for a light source, comprising:

a rechargeable battery;

a first circuit, wherein the first circuit receives an electrical voltage and provides a first charge to the battery,

wherein the electrical voltage comprises one of a first amplitude and a second amplitude, and the first circuit provides the first charge to the battery without regard to whether the electrical voltage comprises the first amplitude and the second amplitude;

a standard mode, wherein a fluorescent lamp is powered using mains power;

an emergency mode, wherein the fluorescent lamp is powered using the battery, wherein the emergency ballast switches from standard mode to emergency mode in response to an interruption in mains power, and switches from emergency mode to standard mode in response to the resumption of mains power; and

a transition circuit configured to delay the transition between the standard mode and the emergency mode, wherein the transition circuit comprises;

a relay, wherein the relay switches the emergency ballast from emergency mode to standard mode;

a transistor, electrically coupled to the relay, wherein the transistor prevents the relay from switching when the transistor is not conductive; and

a capacitor, electrically coupled to mains power and the transistor, the capacitor configured to charge from mains power, wherein after charging the capacitor, current is delivered to the transistor rendering the transistor conductive and causing the relay to switch the emergency ballast into standard mode.

2. The emergency ballast of claim 1, wherein the first charge comprises a charging current for the battery.

3. The emergency ballast of claim 1, wherein the first amplitude is one of 100 volts, 120 volts, 347 volts.

4. The emergency ballast of claim 3, wherein the second amplitude is one of 220 volts, 277 volts, 347 volts, and 600 volts.

5. The emergency ballast of claim 1, further comprising:

a capacitor, electrically coupled to the first circuit, wherein the capacitor provides additional voltage to the rechargeable battery when the electrical voltage comprises the first amplitude; and

a switch that electrically decouples the capacitor from the first circuit when the electrical voltage comprises the second amplitude.

6. The emergency ballast of claim 1, further comprising:

a capacitor, electrically coupled to the first circuit, wherein the capacitor provides additional voltage to the rechargeable battery when the electrical voltage comprises the first amplitude; and

a switch that electrically couples the capacitor to the first circuit when the electrical voltage comprises the second amplitude.

7. The emergency ballast of claim 1, further comprising a charging circuit electrically coupled to the battery and applies a trickle charge to the battery.

8. The emergency ballast of claim 1, wherein the charging circuit applies a charging current to the battery for a first period of time, and applies a trickle charge to the battery after the first period of time.

9. The emergency ballast of claim 8, wherein the charging circuit further comprises a thermal protection circuit, the thermal protection circuit comprising a switch that electrically decouples the charging circuit from the battery when the battery exceeds a predetermined temperature.

10. The emergency ballast of claim 9, wherein the switch comprises a transistor;

and

the thermal protection circuit further comprises;

a thermistor thermally coupled to the battery;

a resistor electrically coupled to the thermistor, wherein the resistor and the thermistor create a voltage divider, and

wherein when the voltage across the resistor exceeds a predetermined level, current is delivered to the transistor, causing the transistor to electrically decouple the battery from the charging circuit.

11. An emergency fluorescent ballast, comprising:

a battery;

a charging circuit for charging the battery, the charging circuit comprising;

an input that receives a charging current from the ballast; and

a timing circuit configured to deliver the charging current to the battery for a predetermined time, the timing circuit further delivering a trickle charging current to the battery after the predetermined time;

a standard mode, wherein a fluorescent lamp is powered using mains power;

an emergency mode, wherein the fluorescent lamp is powered using the battery, wherein the emergency ballast switches from standard mode to emergency mode in response to an interruption in mains power, and switches from emergency mode to standard mode in response to the resumption of mains power; and

a transition circuit that delays the transition between the standard mode and the emergency mode, the transition circuit comprising;

a relay that switches the emergency ballast from emergency mode and standard mode;

a transistor, coupled to the relay, wherein the transistor prevents the relay from switching when the transistor is not conductive; and

a capacitor, coupled to mains power and the transistor, the capacitor receiving a charge from mains power, and wherein in response to the charging of the capacitor, current is delivered to the transistor such that the transistor becomes conductive and causes the relay to switch the emergency ballast into standard mode.

12. The emergency fluorescent ballast of claim 11, wherein the charging circuit further comprises a thermal protection circuit that prevents application of the charge to the battery when the battery exceeds a predetermined temperature.

13. The emergency fluorescent ballast of claim 12, wherein the thermal protection circuit comprises:

a thermistor thermally coupled to the battery;

a resistor electrically coupled to the thermistor, wherein the resistor and the thermistor create a voltage divider, and

wherein when the voltage across the resistor exceeds a predetermined level, current is delivered to a transistor electrically coupled to the battery, causing the transistor to electrically decouple the battery from the charging circuit.

14. The emergency fluorescent ballast of claim 11, wherein the charging current comprises a charging current for the battery, and wherein the trickle charging current comprises a current calculated to keep the battery at a substantially full charge.

15. The emergency fluorescent ballast of claim 11, wherein the battery comprises one of a nickel metal hydride battery, copper oxide battery, iron oxide battery, lithium ion battery, and an iron chloride battery.

16. The emergency fluorescent ballast of claim 11, further comprising a circuit receiving an electrical voltage and providing the charging current to the battery, wherein the electrical voltage comprises one of a first amplitude and a second amplitude, and the circuit provides the charging current to the battery without regard to whether the electrical voltage comprises the first amplitude and the second amplitude.

17. The emergency fluorescent ballast of claim 16, wherein the first amplitude is 120 volts, and the second amplitude is 277 volts.

18. A method for providing emergency power to a light source, the method comprising:

receiving a current from mains power;

converting the current from mains power to a charging current for a battery;

providing the charging current to the battery for a predetermined time;

providing a trickle charge after the predetermined time has elapsed;

monitoring the temperature of the battery to determine whether the temperature of the battery has exceeded a predetermined temperature;

preventing the application of current to the battery in response to determining that the battery has exceeded the predetermined temperature;

determining if mains power exceeds a predetermined amplitude; and

charging a capacitor to provide additional charge in response to determining that mains power does not exceed the predetermined amplitude.

19. The method of claim 18, further comprising electrically decoupling the capacitor in response to determining that mains power exceeds the predetermined amplitude.

20. The method of claim 18, further comprising;

operating the fluorescent lamp using power from the battery;

preventing the ballast from powering the lamp with the mains power for a second predetermined time; and

powering the lamp with the ballast using the mains power after the second predetermined time.