Backup protection switch to prevent reverse power flow in a UPS
First Claim
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1. In combination:
- an uninterruptible power supply, comprising;
a first input for accepting a primary source of energy,a second input for accepting a reserve source of energy,an output for accepting a load to be energized,energy coupling means for coupling energy from the first and second inputs to the output,at least a first energy path including the energy coupling means for permitting energy flow from the second input to the first input,primary means for disabling energy flow in the first energy path when energy flow to the output is derived from the reserve source of energy connected to the second input,means for detecting a failure of the primary means for disabling energy flow,secondary means for disabling connection of the first energy path to the first input in response to the means for detecting a failure.
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Abstract
A UPS system includes a backup input line isolation switch and control circuit for energy flow in the UPS is operative, during operation of the reserve energy source portion of the power supply in supplying power to the output, to provide mechanical isolation between the primary energy source connected to the input line and the secondary energy source upon detection of a failure of an electronic isolation switch normally providing isolation between te input line and the secondary energy source or an output of the UPS.
118 Citations
10 Claims
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1. In combination:
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an uninterruptible power supply, comprising; a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, energy coupling means for coupling energy from the first and second inputs to the output, at least a first energy path including the energy coupling means for permitting energy flow from the second input to the first input, primary means for disabling energy flow in the first energy path when energy flow to the output is derived from the reserve source of energy connected to the second input, means for detecting a failure of the primary means for disabling energy flow, secondary means for disabling connection of the first energy path to the first input in response to the means for detecting a failure.
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2. In combination:
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an uninterruptible power supply, comprising; a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, an energy coupling apparatus for coupling energy from the first and second inputs to the output, at least a first energy path including the energy coupling apparatus for permitting energy flow from the second input to the first input, primary means for disabling energy flow in the first energy path when energy flow is connected through the energy coupling apparatus from the second input to the output, means for detecting a failure of the primary means for disabling energy flow, secondary means for disabling connection of the first energy path from the first input in response to the means for detecting a failure.
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3. In combination:
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an uninterruptible power supply, comprising; a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, an energy coupling apparatus for coupling energy from the first and second inputs to the output and capable of coupling energy from the second input to the first input, a primary disconnect switch for decoupling the first input from the energy coupling apparatus when energy is being supplied to the output from the second input, a backup disconnect switch for disabling energy flow from a reserve energy source connected to the second input into the first input, means for facilitating a flow of energy from the second input to the first input should the primary disconnect switch fail in a mode enabling energy flow through the primary disconnect switch. means for sensing reverse energy flow from the energy coupling apparatus to the first input, means for ascertaining when energy is being supplied to the output from the second input, means responsive to concurrence of the means for sensing and the means for ascertaining for activating the backup disconnect swtich.
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4. In combination:
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an uninterruptible power supply, comprising; a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, an energy coupling apparatus for coupling energy from the first and second inputs to the output and capable of coupling energy from the second input to the first input, a bypass line connecting the first input to the output and a second disconnect switch for disabling the bypass line, and a primary disconnect switch for decoupling the first input from the energy coupling apparatus when energy is being supplied to the output from the second input, a backup disconnect switch for disabling energy flow from the second input to the first input and from the output to the first input via the bypass line, means for facilitating a flow of energy from the second input to the first input should the primary disconnect switch fail in a mode enabling energy flow through the primary disconnect switch, means for sensing energy flow from the second input to the first input, means for ascertaining when energy is being supplied to the output from the second input, means responsive to concurrence of the means for sensing and the means for ascertaining for activating the backup disconnect switch.
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5. In combination:
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an uninterruptible power supply, comprising; a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, a power transformer having first and second primary windings coupled to the first and second inputs respectively and a secondary winding connected to the output; and
the power transformer being capable of coupling energy from the second input to the first input,a primary semiconductor disconnect switch for decoupling the first input from the power transformer when energy is being supplied to the output from the second input, a backup mechanical disconnect switch for disabling energy flow from a reserve energy source connected to the second input into the first input, a high impedance conducting path shunting the input sized for facilitating a flow of energy greater than leakage current levels from the second input to the first input should the primary semiconductor disconnect switch fail in a shorted mode enabling energy flow through the primary semiconductor disconnect switch, a first current flow sense device for sensing reverse energy flow from the power transformer to the first input, a second current flow sense device for ascertaining when energy is being supplied to the ouput from the second input, control circuitry responsive to concurrence of energy flow in the first and second current flow sense devices for activating the backup mechanical disconnect switch.
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6. In combination:
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an uninterruptible power supply, comprising; a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, a power transformer having first and second primary windings coupled to the first and second inputs respectively and a secondary winding connected to the output; and
the power transformer being capable of coupling energy from the second input to the first input,a bypass line connecting the first input to the output, a primary semiconductor disconnect switch for decoupling the first input from the power transformer and a bypass semiconductor switch for disabling conduction in the bypass line when energy is being supplied to the output from the second input, a backup mechanical disconnect switch for disabling current flow from a reserve energy source connected to the second input into the first input, a high impedance conducting path shunting the input sized for facilitating a flow of current greater than leakage current levels from the second input to the first input should at least one of the primary semiconductor and bypass semiconductor disconnect switches fail in a shorted mode, a first current flow sense device for sensing reverse current flow from the power transformer to the first input, a second current flow sense device for ascertaining when energy is being supplied to the output from the second input, control circuitry responsive to concurrence of current flow in the first and second current flow sense devices for activating the backup mechanical disconnect switch.
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7. In combination:
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an uninterruptible power supply, comprising; a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, a power transformer having first and second primary windings coupled to the first and second inputs respectively and a secondary winding connected to the output; and
the power transformer being capable of coupling energy from the second input to the first input,a bypass line connecting the first input to the output, a primary semiconductor disconnect switch for decoupling the first input from the power transformer and a bypass semiconductor switch for disabling conduction in the bypass line when energy is being supplied to the output from the second input, a backup mechanical disconnect switch for diabaling current flow from a reserve energy source connected to the second input into the first input, a high impedance conducting path shunting the input sized for faciltating a flow of current greater than leakage current levels from the second input to the first input should at least one of the primary semiconductor and bypass semiconductor disconnect switches fail in a shorted mode, a current sense transformer having a primary winding connected for sensing reverse current flow from the power transformer to the first input, a current shunt device connected for ascertaining current flow into the second input when energy is being supplied to the output from the second input, control circuitry responsive to concurrence of current flow in the first and second current flow sense devices, comprising; a peak detector coupled to a secondary winding of the current sense transformer, a first comparator fro comparing a current level of the peak detector with a first reference level set to identify current levels above leakage current levels, a second comparator connected for comparing current in the current shunt device with a second reference level, and circuitry responsive to the output states of the first and second comparators for activating the backup mechanical disconnect switch.
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8. In combination:
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an uninterruptible power supply comprising; a first input for accepting a primary AC voltage source, a rectifier connected to receive AC voltage applied to the input and supply a rectified DC voltage, a static inverter having a signal input arrangement connected to receive the rectified DC voltage and generate an AC voltage signal and an inverter output, a second input for accepting a reserve DC voltage source and connected in parallel with the signal input arrangement of the inverter, the output of the inverter adapted for accepting a load to be energized, a bypass line for directly connecting to the first input to the output of the inverter, an electronic switch for disabling the bypass line, means for detecting a failure of the electronic switch, a mechanical switch responsive to the means for detecting a failure of the electronic switch and positioned for disconnecting the first input from the bypass line and from the rectifier.
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9. An uninterruptible power supply in which an electronic switch failure may permit reverse energy flow from a reserve source of energy into a primary source of energy, comprising:
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a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, energy coupling means for coupling energy from the first and second inputs to the output, an electronic switch for disabling reverse energy flow into the first input when energy flow to the output is derived from the reserve source of energy connected to the second input, means for detecting a failure of the electronic switch for disabling reverse energy flow, a mechanical switch for disabling reverse energy flow to the first input operative in response to the means for detecting a failure.
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10. An uninterruptible power supply in which a switch failure may permit reverse energy flow from a reserve source of energy into a primary source of energy, comprising:
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a first input for accepting a primary source of energy, a second input for accepting a reserve source of energy, an output for accepting a load to be energized, an energy coupling apparatus for coupling energy from the first and second inputs to the output, a primary switch for disabling reverse energy flow into the first input'"'"' when energy flow is connected through the energy coupling apparatus from the second input to the output, means for detecting a failure of the primary switch for disabling reverse energy flow, a secondary switch for disabling reverse energy flow into the first input operative in response to the means for detecting a failure.
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Specification
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Current AssigneeAmerican Telephone & Telegraph Company (AT&T, Inc.), Bell Telephone Laboratories, Inc. (Nokia Corporation)
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Original AssigneeAmerican Telephone & Telegraph Company (AT&T, Inc.)
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InventorsGvoth, John Michael Jr., Menkes, Henry E., Kakalec, Robert J.
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Primary Examiner(s)Beha, Jr., William H.
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Application NumberUS07/099,042Time in Patent Office323 DaysField of Search307/46, 307/64, 307/65, 307/66, 307/86, 361/84, 361/82, 361/102, 361/3US Class Current307/66CPC Class CodesH02J 9/062 for AC powered loads
