US 5,452,173 A · Diagnostic circuit protection device

Abstract

A circuit protection device for use with an electrical unit comprises driver circuitry connected to the electrical unit and connecting means electrically connecting the device to the electrical unit to provide a voltage signal indicative of a voltage associated with the electrical unit. A voltage detector is connected to the connecting means and receives the voltage signal, and provides a conditioned voltage signal output representative of the voltage signal. An analog-to-digital converter receives the conditioned voltage signal output and converts the conditioned voltage signal output to a digital value. A digital processing device receives the digital value from the analog-to-digital converter and provides an output signal to the driver circuitry to turn off power to the primary if an error is detected. The device may also include current obtaining means for providing an electrical signal indicative of a current associated with the electrical unit, and a current detector circuit connected to and receiving that electrical signal for providing an output voltage signal representative thereof. Multiplexing means may be provided for receiving the output signals from both the voltage detector and the current detector for selectively connecting only one of those signals at a time to the analog-to-digital converter. Alternatively, a second analog-to-digital converter may receive the second output voltage signal and convert it to a digital value, and the digital processing device may receive and process the digital values from both analog-to-digital converters.

Claims22

Dependent claims

A circuit protection device, comprising:

a driver circuit adapted during use for connection between an electrical unit and an AC power source;
a detection circuit adapted for connection to said electrical unit for sensing a fault condition of said electrical unit within one half-cycle of said AC power source;
and
a digital processing device coupled between said detection circuit and said driver circuit, for receiving a digital representation of said fault condition and for disconnecting said AC power source from said electrical unit during times in which a value of said digital representation is outside a pre-programmed range of values stored with said digital processing device.

1 more element

A method of protecting an electrical unit which receives operating power in the form of a periodic signal, using a digital processing device, comprising:

(A) providing said digital processing device with a data base for said electrical unit comprising,
(1) a voltage fault tolerance value for a voltage associated with said electrical unit,
(B) calibrating the digital processing device by
(1) digitally sampling said voltage to obtain a digital calibration value;
(2) calculating within said digital processing device a voltage fault limit based on said digital calibration value and said voltage fault tolerance value;
and
(C) performing the following steps within each period of said periodic signal during operation of the electrical unit,
(1) digitally sampling said voltage associated with said electrical unit at frequent intervals to obtain a series of representative digital voltage values;
(2) providing said digital processing device with said representative digital voltage values;
(3) determining, within said digital processing device, whether said representative digital voltage values have surpassed said voltage fault limit;
(4) switching off said operating power whenever said determination indicates that said voltage fault limit has been surpassed.

8 more elements

Dependencies are inferred from the claim text.

Diagnostic circuit protection device

Life of this patent

Diagnostic circuit protection device

Life of this patent

Abstract

Claims22