AC-DC transfer standard overload protection circuit
AssigneeBallantine Laboratories, Inc.
InventorsJerry Harper, Archie J. Harrison, Jr.
Life of this patent
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Abstract
An overload protection circuit for an AC-DC transfer standard employing a thermoelement comprising a heater element and a temperature sensor. A first differentiator provides an output that is a function of the voltage across the heater element. A second differentiator produces an output that is a function of the output of the first differentiator. Further including a circuit creating an overload signal provided, which is responsive to the outputs of the first and second differentiators.
Claims15
An overload protection circuit for a thermal transfer device having a fine wire heater element and a temperature sensor, the temperature sensor generating a sensor signal whose amplitude is dependent upon the amplitude of the voltage across the heater element, the temperature sensor being in thermal contact with the heater element, said protection circuit comprising:
- (a) a first differentiator responsive to the amplitude of the sensor signal and producing a differentiated output signal;
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- (b) a second differentiator responsive to the output signal from the first differentiator and producing a twice differentiated output signal;
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- (c) means for actuating an overload signal responsive to the output signal of the first differentiator or second differentiator.
An overload protection circuit for a thermal transfer device having a fine wire heater element and a temperature sensor, the temperature sensor generating a sensor signal whose amplitude is dependent upon the amplitude of the voltage across the heater element, the temperature sensor being in thermal contact with the heater element, said protection circuit comprising:
- (a) a first differentiator responsive to the amplitude of the sensor signal and producing a differentiated output signal;
- (b) a second differentiator responsive to the output signal from the first differentiator and producing a twice differentiated output signal;
- (c) means for summing connected to receive and serve the differentiated output signal from the first differentiator and the twice differentiated output signal from the second differentiator, said summing means producing a sum signal as a result of such summing;
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Dependencies are inferred from the claim text.