The present invention is related to fault insertion, calibration and test of electrical equipment.
Test equipment is used to test the operation of electrical equipment, including the ability of the equipment to handle electrical faults, such as open circuits and short circuits. Fault insertion is provided by connecting faults (e.g., short-circuit faults, open-circuit faults) to the equipment being tested, referred to as the “unit under test” or UUT, and outputs are monitored. Each fault to be inserted requires manual connection of the faults to the UUT, which is a tedious and error-prone process.
In addition to fault insertion, test equipment also verifies the operation of the UUT, simulating inputs provided to the UUT and monitoring the response of the UUT. Depending on the aspect of the UUT to be tested, various outputs of the UUT are monitored, and various inputs are provided by the test equipment to the UUT. Each test operation requires manual connection of the test equipment to the UUT to accommodate the test to be performed.
To provide meaningful results the test equipment must be properly calibrated to ensure the signals provided to the UUT are proper. Calibration of the test equipment is wholly separate from testing of the UUT, and again requires manual configuration, monitoring, and measuring of various signals to ensure their accuracy.
A fault insertion, calibration and test system includes an input connection terminal, for connection to an external unit under test (UUT), an output connection terminal for connection to test equipment, and at least first and second bus circuit binding posts, each connectable to external devices. The system further includes a plurality of switch matrices, each connected to an input contact associated with the input connection terminal and an output contact associated with the output connection terminal and at least first and second common buses that connect to each switch matrix and to the bus circuit binding posts. Each switch matrix has a plurality of switches connected between the input contact, the output contact, and the common buses that are selectively configured to form connections between the input contact and the output contact, between the input contact and each of the common buses and between the output contact and each of the common buses.
The present invention provides a system and method for interfacing units under test (UUTs) to test equipment that allows for fault insertion, a variety of different test configurations and test equipment calibration. The fault insertion, calibration and test system (referred to herein as the FIT system) includes a plurality of switches, organized into a plurality of switch matrices that allows various connections to be made between the UUT and the test equipment. In addition, the FIT system includes a plurality of common buses connected to external binding post connectors that allow for various connections to be made between the input and outputs of the UUT and test equipment and to allow for various signals to be monitored or injected into the UUT and/or the test equipment. In this way, the FIT system provides an interface that, once connected, allows electrical faults to be inserted, a plurality of testing configurations to be implemented, and test equipment to be calibrated, all without having to manually re-configure or re-connect the system.
Output connection terminal 16 similarly consists of a plurality of individual pin connections or contacts (referred to subsequently as output contacts 16-1, 16-1, . . . 16-n), used to provide an interface for connecting FIT system 10 to test equipment. In the embodiment shown in
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In the exemplary embodiment shown in
In the embodiment shown in
User interface 36 is connected via communication interface terminals 23a, 23b to provide control instructions to controller 38. In the embodiment shown in
For example, selective control of switches within each switch matrix 34 allows connections to be selectively made between UUT contact 30-1 and test equipment contact 32-1, such that a signal generated by test equipment 26 at test equipment contact 32-1 is communicated to UUT contact 30-1 of UUT 24. Conversely, an output generated by UUT 24 at UUT contact 30-1 may be communicated to test equipment contact 32-1 of test equipment 26. An open circuit condition may be created between UUT contact 30-1 of UUT 24 and test equipment contact 32-1, thereby simulating an open-circuit fault for UUT 24. In addition, selective control of switches within switch matrices 34 allows the various contacts of UUT 24 and/or test equipment 26 to be selectively connected to each of the common buses A, B, C, and D associated with bus circuit binding posts 22a-22d. Depending on the application, signals may be injected via bus circuit binding posts 22a-22d into UUT 24 and/or test equipment 26, signals generated by UUT 24 and/or test equipment 26 may be monitored at bus circuit binding posts 22a-22d, or combinations thereof.
A benefit of FIT system 10, is that once connected it allows a user to connect UUT 24, test equipment 26, and devices connected to bus circuit binding posts 22a-22d in a variety of configurations through instructions provided by user interface 36, without requiring manual re-connection of various input/output terminals, etc. For example, in one configuration test equipment 26 is connected to communicate with UUT 24 through FIT system 10, without test equipment 26 being aware of the presence of FIT system 10, so that test equipment 26 can test the operation of UUT 24. Selective faults can be introduced by FIT system 10 between UUT 24 and test equipment 26, and the operation of test equipment 26 can be calibrated even while connected to UUT 24. The selection of switches to be energized is provided by an operator via communication interface terminal (e.g., communication interface terminals 23a, 23b shown in
In the embodiment shown in
Each of the switches in switch matrix 34-1, 34-2 is shown in the non-energized state. Switch K1 is connected between input contact 14-1 and output contact 16-1, providing a circuit path between the two contacts in the non-energized state, and opening the circuit path between the two contacts in the energized state. Switches K2-K4 determine whether the input contact 14-1 and output contact 16-1 are connected to the common bus lines A-D, as well as the particular common bus line to which they are connected. Switch K2 is connected between the line connecting input contact 14-1 to output contact 16-1, and a plurality of switches for selective connection to one of the common bus lines. In the non-energized state, switch K2 prevents connection of either input contact 14-1 or output contact 16-1 to the common bus lines A-D. In the energized state, switch K2 provides a circuit path to one of the common bus lines, depending on the state of switches K3 and K4. Switches K3 and K4 together select the particular common bus line to which the input contact 14-1 and/or output contact 16-1 is connected. Connection is made to common bus A if both switches K3 and K4 are non-energized. Connection is made to common bus B if switch K3 is non-energized and switch K4 is energized. Connection is made to common bus C if switch K3 is energized and switch K4 is non-energized. Connection is made to common bus D if switch K3 is energized and switch K4 is energized. The connection of switches K5-K8 in switch matrix 34-2 is the same as described with respect to switch matrix 34-1.
The following table illustrates each of the possible states associated with switches K1-K4, and describes the resulting connection made as a result of the particular switch configuration. The same configuration table applies to the configuration of switches K5-K8 provided with respect to switch matrix 34-2.
Line 1 of Table 1 indicates that the normal state of each channel is with none of the switches energized, thus providing a connection from input contact 14-1 to output contact 16-1, and from input contact 14-2 to output contact 16-2. Lines 2-5 relate to states in which K2 is energized, thereby shorting input contact 14-1 and output contact 16-1 to one of the four common buses A-D. Line 6 relates to the state in which switch K1 is energized and switch K2 is non-energized, creating an open-circuit fault between input contact 14-1 and output contact 16-1 (i.e., injecting an open-circuit fault into input contact of the unit under test). Lines 7-10 relate to states in which switches K1 and K2 are energized, thereby disconnecting input contact 14-1 from the switch matrix and connecting the output contact 16-1 associated with the test equipment to one of the plurality of common buses, A-D.
As described with respect to lines 2-5, in which one or more contacts of input terminal 14 and one or more contacts of output terminal 16 are shorted to common buses A, B, C, or D, various fault conditions may be simulated. For example, simulated ground can be connected via bus circuit binding posts 22a-22d to simulate a ground fault at one of the input contacts 14 and/or output contacts 16. By connecting two or more input contacts 14-1, 14-2 to the same common bus, contact-to-contact shorts can be simulated. In addition, by connecting two or more FIT systems together via bus circuit binding posts 22-22d, multiple contact shorts on two or more UUTs may be tested. As described with respect to lines 7-10, by connecting various meters and/or signal sources to bus circuit binding posts 22a-22d, test equipment 26 can be calibrated.
When transitioning between various switching states, user interface 36 and/or controller 38 (shown in
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Transformer 62 provides an AC signal at winding 63a in response to an AC signal provided at winding 63b. Measurement of the signals generated in response to a test signal allows the test equipment to be calibrated to correctly interpret signals received from the unit under test during test operations. To this end, signal generator 66 injects a signal via bus circuit binding posts 22c and 22d that is communicated via common buses C and D, switch matrices 34-3 and 34-4 to output contacts 16-3 and 16-4, respectively. The injected signal is provided to winding 63b of transformer 62. The resulting signal generated at winding 63a is communicated via output contacts 16-1, 16-2, switch matrices 34-1, 34-2, and common buses A, B to bus circuit binding posts 22a, 22b, respectively. Measurement device 64 monitors the signal, and provides feedback to computer 68 regarding the measured signal.
In this embodiment, all four common buses are employed as part of the calibration process, with two of the common buses being employed to communicate a generated signal to output contacts of FIT system 10, and two of the common buses being employed to communicate signal received at output contacts to bus circuit binding posts.
The examples described with respect to
While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.