Automatic bipolar signal switching

A system is provided that includes an input node configured to receive a signal indicative of sensor data. The system also includes a first transistor configured to route the signal to a positive channel when a polarity of the signal is positive. Moreover, the system includes a second transistor configured to route the signal to a negative channel when a polarity of the signal is negative. Additionally, the system includes the positive channel coupled to the first transistor configured to route the signal to an analysis component. Furthermore, the system includes the negative channel coupled to the second transistor and configured to route the signal to the analysis component.

BACKGROUND

The subject matter disclosed herein generally relates to signal routing to an electrical device based on a polarity of the signal.

To enable an electrical device (e.g., instrumentation device) to couple to a variety of components (e.g., transducers) that may have either a positive polarity (e.g., AC signal with +12 DC offset) or a negative polarity (e.g., AC signal with a −12 DC offset), multiple terminals in the electrical device with a dedicated terminal for expected voltages may be utilized. However, such devices include unused terminals (depending on the implementation of the device) to be included in the device, thereby increasing production costs of the device inefficiently. Other electrical devices may instead include an analog multiplexer (MUX) circuit coupled between a terminal and internal circuitry to allow a device to be coupled to a variety of components. However, these devices are often vulnerable to damage due to a susceptibility of the MUX to damage caused by electrostatic discharge (ESD) and other shock events. Alternatively, some electrical devices may require a user to manually (e.g., physically) change a configuration to a desired setting (e.g., positive polarity). However, requiring a manual setting may result in a user not changing the setting correctly and/or before each use thereby increasing the likelihood of damage to the electrical device or other unwanted results.

Other electrical devices may instead use large rail amplifiers (e.g., allow a 36V variance) to increase a tolerated voltage range in a signal on a single pin. However, large rail amplifiers typically sacrifice accuracy for flexibility and are often unable to achieve the accuracy requirements for many implementations (e.g., measurement systems). Moreover, large rail amplifiers also are more expensive than traditional amplifiers. Furthermore, large rail amplifiers are becoming more rare in implementation, thereby reducing the demand, production, and support of large rail amplifiers.

As an alternative to large rail amplifiers, some electrical devices may attenuate the signal as it enters into an input module. However, by reducing the amplitude of the signal, the electrical device also significantly reduces the signal-to-noise ratio of the attenuated signal. By reducing the signal-to-noise ratio, electrical devices that attenuate the input signal often are unable to produce accurate outputs for small input ranges.

BRIEF DESCRIPTION

In one embodiment, a system includes an input node configured to receive a signal indicative of sensor data. The system also includes a first gating device electrically coupled to the input node. The gating device is configured to couple the input node to a positive channel when a polarity of the signal is positive and to decouple the input node from the positive channel when the polarity of the signal is negative. Furthermore, the system includes a second gating device electrically coupled to the input node. The second gating device is configured to couple the input node to a negative channel when the polarity of the signal is negative and to decouple the input node from the positive channel when the polarity of the signal is positive.

In another embodiment, a system includes an input node configured to receive a signal indicative of sensor data. The system also includes a first transistor configured to route the signal to a positive channel when a polarity of the signal is positive. Moreover, the system includes a second transistor configured to route the signal to a negative channel when a polarity of the signal is negative. Additionally, the system includes the positive channel coupled to the first transistor configured to route the signal to an analysis component. Furthermore, the system includes the negative channel coupled to the second transistor and configured to route the signal to the analysis component.

In a further embodiment, a method for channeling a signal according to polarity includes receiving a signal having both a DC and AC component. Moreover, the method also includes determining a polarity of the DC component. Furthermore, the method includes toggling a positive switch closed and toggling a negative switch open to route the signal through a positive channel if the polarity is positive. The method also includes toggling the negative switch closed and toggling the positive switch open to route the signal through a negative channel if the polarity is negative.

DETAILED DESCRIPTION

As discussed in detail below, a system that automatically routes a signal depending on the polarity of a signal without requiring user selection and/or configuration reduces a likelihood of connection of voltages that an electrical device is not correctly configured manually by the user. Moreover, a system that channels the signal using a polarity of the signal, the signal can be analyzed without attenuating the signal thereby reducing a signal to noise ratio of the signal causing less accurate signals without including an analog multiplexer that is susceptible to ESD or other shock events. Furthermore, a system that channels the signal using a polarity of the signal, the signal can be conditioned (e.g., amplified) without using large rail operational amplifiers that are more expensive than traditional op amps and have decreased accuracy unsuitable for many intended uses of an electrical device. In other words, by channeling the signal according to polarity, a system with a robust design may be included that is less susceptible to ESD, improper connections, or loss of accuracy that may be present in alternative electrical devices.

FIG. 1is a block diagram view of an embodiment of an electrical device10. In some embodiments, the electrical device10may include an instrumentation system, such as a monitoring system similar to a 3500 Series Machinery Protection System with Bently Nevada™ Asset Condition Monitoring made available by General Electric® of Schenectady, N.Y. The illustrated electrical device10includes one or more terminals12that are configured to electrically couple to a data connector14(e.g., data cable, wire, etc.). Although the illustrated electrical device10includes three terminals12, some embodiments of the electrical device10may include one, two, three, or more terminals. Additionally, some embodiments of the electrical device10may have a variable number of terminals through the use of a “rack-based design” to increase flexibility of use of the electrical device10. In certain embodiments, each of the terminals12may couple to a data connector14. In some embodiments, the terminals12may be decoupled from a respective data connector14when the terminal is not used. For example, in some embodiments, the data connector14and/or the terminal12may include one or more suitable electrical connectors, such as Bayonet Neill-Concelman (BNC) connectors, plug and socket connectors, posts, and/or terminal blocks. In certain embodiments, the data connector14also couples to electrical component16. In some embodiments, the data connector14may be fixed to the electrical component16. In other embodiments, the data connector14may be removably coupled to the electrical component16using a suitable removable electrical connector.

In certain embodiments, the electrical component16may include various electrical devices, such as transducers or other suitable measurement devices that are used to measure various parameters of a monitored system18. For example, the electrical component16may include a velocity sensor, acceleration sensor, proximity sensor, eddy current sensor, rotation sensor, pressure sensor, or other suitable measuring devices. Additionally, the electrical component16may include various types of interfaces, such as a one-wire interface, a two-wire interface, a three-wire interface, or another suitable interface. In some embodiments, the monitored system18may include one or more of the following: steam turbines, hydraulic turbines, industrial gas turbines, aeroderivative turbines, compressors, gears, turbo-expanders, centrifugal pumps, motors, generators, fans, blowers, agitators, mixers, centrifuges, pulp refiners, ball mills, crushers/pulverizers, extruders, pelletizers, cooling towers/heat exchanger fans, and other systems suitable to be electrically monitored. In various embodiments, a signal20(e.g., electrical signal representing air pressure in the monitored system18) is sent via the data connector14from the electrical component16to the electrical device10.

Upon receiving the signal20from the electrical component16via the data connector14, the electrical device10routes the signal20to a polarity channeling component22. Various electrical components16may include AC and DC components with a polarity of the DC component varying according to the type/manufacturer of electrical component16. As discussed below, the polarity channeling component22routes the signal20to an appropriate analysis component24according to polarity of the signal20. The analysis component24may convert the signal20to a desired format. For example, in some embodiments, the analysis component24may condition the signal20for use by the electrical device10. Additionally, some embodiments of the analysis component24may track values indicated by the signal20and determine whether the value falls within a tolerance range. In some embodiments, the analysis component24may cause an alarm to be triggered when the measured value exceeds a tolerance range or a monitoring connection has faulted (e.g. broken wire).

Furthermore, the electrical device10may include one or more status indicators26. In some embodiments, the status indicators26may indicate that the electrical device10is powered on. The indicators26may additionally and/or alternatively display information representing a status of the monitored system18(e.g., standby, alarms, etc.). In certain embodiments, one or more of the indicators26may represent whether there is a fault (e.g., monitored system18is not being properly monitored due to a broken wire, etc.) in the monitored system18, the electrical component16, the data connector14, and/or the electrical device10.

FIG. 2is a schematic diagram view of an embodiment of circuitry30that may be used in the electrical device10. As illustrated, the circuitry30includes the polarity channeling component22and at least a portion of the analysis component24. In the illustrated embodiment, the analysis component24includes a negative polarity conditioning circuit32and a positive polarity conditioning circuit34. As discussed below, the signal20is routed to the positive polarity conditioning circuit34when the signal20has a positive polarity and to the negative polarity conditioning circuit32when the signal20has a negative polarity. As discussed below, in some embodiments, the polarity channeling component22may channel into a single conditioning circuit (e.g., positive polarity conditioning circuit34). In such embodiments, the signal20may be routed through an inverter prior entrance into a conditioning circuit.

To route the signal20based on the polarity of the signal20, the polarity channeling circuit22first receives the signal20from the terminal12. In some embodiments, additionally circuitry may be included to modify the signal20(e.g. filter and/or amplify) prior to receipt by the polarity channeling circuit22. Additionally or alternatively, in certain embodiments, the polarity channeling circuit22may include signal refining components. For example, after the signal20is received by the polarity channeling circuit22, some embodiments of the polarity channeling circuit20may include an RC filter36that extracts a DC component of the signal20using a filter resistor38(through which the signal20passes) and a filter capacitor40coupled between a filter node42and ground44. In some embodiments, values for the resistor38and the capacitor40may be selected to extract the DC component of the signal20at filter node42.

In certain embodiments, the voltage at the filter node42is coupled to a negative switch46and a positive switch48. As illustrated, in some embodiments the negative switch46and the positive switch48are n-channel metal-oxide semiconductor field-effect transistors (NMOS) biased in opposite directions. However, other embodiments may include various other transistors such as junction field-effect transistor (JFET) devices, other metal-oxide semiconductor field-effect transistor (MOSFET) devices (e.g., PMOS) bipolar junction transistors (BJTs), or other suitable switching devices.

As can be appreciated, when the voltage at the filter node42reaches a sufficiently negative value, the voltage (e.g., VGS, VAS) across the negative switch46exceeds the voltage threshold (VTH) of the negative switch46, thereby causing the negative switch46to toggle into a closed state, thus enabling a current flow across the negative switch46through a negative channel49. Accordingly, when the voltage of the signal20is negative, the negative switch46routes the signal20to the negative polarity conditioning circuit32via the negative channel49. Furthermore, when the voltage at the filter node42is negative, the voltage across the positive switch48does not exceed the VTHrequired to close the switch. Accordingly, the positive switch48is open when the voltage at the filter node42is negative.

As noted above, when the negative switch46is closed, current flows along the negative channel49to the negative polarity conditioning circuit32. In some embodiments, the negative polarity conditioning circuit32includes filtering circuitry, voltage offsetting, and/or other signal conditioning readily known in the field of signal conditioning. As illustrated, some embodiments of the negative polarity condition circuit32include voltage amplification circuitry50. For example, the voltage amplification circuitry50may include an operational amplifier52(op-amp) amplifier in a suitable configuration, such as inverting amplifier circuits, non-inverting circuits, and/or other suitable amplification circuits. Moreover, the op-amp52may be powered using a +Vcc54and a −Vcc56that may each be selected according the expected parameters of the signal20. For example, in some embodiments, the +Vcc54of the negative polarity conditioning circuit32may be +5V and the −Vcc56may be −24V, and the +Vcc54of the positive polarity conditioning circuit34may be +24V and the −Vcc56may be −5V. However, other suitable voltages may be used according to expected parameters of the signal20.

As illustrated, in embodiments of the voltage amplification circuitry50using the op-amp52, a feedback loop58is included. In certain embodiments, the feedback loop58includes a feedback resistor60that may be selected according to a desired amplification factor. For example, in certain embodiments, the feedback resistor60may be 20 kΩ or another suitable resistance value. Some embodiments of the feedback loop58include a feedback capacitor62in addition to the feedback resistor60. The inclusion of the feedback capacitor62may be included to compensate for parasitic capacitance at an input64of the op-amp52. The feedback capacitor62may also be included to reduce gain at higher frequencies. In various embodiments, the feedback capacitor62may include a relatively small capacitance capacitor, such as a 100 pF or another suitable capacitance capacitor. After the signal20having a negative polarity is conditioned by the negative polarity conditioning circuit32, the signal20is then output through the negative out65. In some embodiments, the signal at the negative out65may be further analyzed by the analysis component24and/or the electrical device10.

As can be appreciated, when the voltage at the filter node42is sufficiently positive instead of negative, the voltage (e.g., VGS, VDS) across the positive switch48exceeds the voltage threshold (VTH) of the positive switch48, thereby causing the positive switch48to toggle into enabling a current flow across the positive switch48through a positive channel66. Accordingly, when the voltage of the signal20is positive, the positive switch48routes the signal20to the positive polarity conditioning circuit34via the positive channel66. Furthermore, when the voltage at the filter node42is positive, the voltage across the negative switch46does not exceed the VTHrequired to close the switch. Accordingly, the positive switch48is open when the voltage at the filter node42is positive.

In some embodiments, the positive polarity conditioning circuit34includes filtering circuitry, voltage offsetting, and/or other signal conditioning readily known in the field of signal conditioning. Similar to the negative polarity conditioning circuit32, some embodiments of the positive polarity condition circuit34include voltage amplification circuitry50. As discussed above, certain embodiments of the voltage amplification circuitry50may include an operational amplifier52(op-amp) amplifier circuits, such as inverting amplifier circuits, non-inverting circuits, and/or other suitable amplification circuits.

After the signal20having a positive polarity is conditioned by the positive polarity conditioning circuit34, the signal20is then output through the positive out67. In some embodiments, the signal at the positive out67may be further analyzed by the analysis component24and/or the electrical device10. The measured values of the signal20at the outs65,67may be used to affect a status of the indicators26and/or other functions of the electrical device10and/or electrical component16.

Furthermore, in some embodiments, one channel (e.g. positive channel66) may be inverted and routed through an opposite polarity conditioning circuit (e.g., negative polarity conditioning circuit34). Moreover, certain embodiments may have a single out that may be connected to the negative out65and the positive out67. For example, some embodiments may include the voltage amplification circuitry50arranged in a non-inverting amplifier configuration in the negative polarity conditioning circuit34and/or positive polarity conditioning circuit36and the voltage amplification circuitry50arranged in an inverting amplifier configuration in the negative polarity conditioning circuit34and/or positive polarity conditioning circuit36.

FIG. 3is a schematic diagram view of an alternative embodiment of the circuitry30that may be included in the electrical device10. In the illustrated embodiment of the polarity channeling circuit22, the polarity channeling circuit22includes a negative switch70and a positive switch72. The gate of each switch is connected to ground74. As the signal20enters the polarity channeling circuit22, the polarity of the signal20switches the appropriate switch70or72by modifying the voltage difference between the gate and the source/drain of the switch70and72due to change of the voltage of the source/drain. When the voltage (e.g., VGS, VDS) crosses the threshold voltage (VTH) used to toggle the switch into a transmitting mode (e.g., saturation). For example, when the voltage of the signal20is negative, the negative switch70routes the signal to the negative polarity conditioning circuit32via the negative channel49while the positive switch72remains toggled open. When the voltage of the signal20is positive, the negative switch70toggles open and the positive switch72toggles closed, thereby routing the signal20to the positive polarity conditioning circuit34via the positive channel66. In other words, the polarity channeling circuit22routes the signal20according to the polarity of the signal.

Moreover, once the signal20is routed to the negative polarity conditioning circuit32or the positive polarity conditioning circuit34, the signal20may be processed and/or conditioned in a suitable manner. For example, the signal20may be amplified using the amplification circuits50described above in relation toFIG. 2. Furthermore, the electrical device10, the polarity channeling circuit22, the negative polarity conditioning circuit32, and/or the positive polarity conditioning circuit34may include additional circuitry used to add/remove additional desired characteristics to/from the signal. For example, the electrical device10, the polarity channeling circuit22, the negative polarity conditioning circuit32, and/or the positive polarity conditioning circuit34may include additional resistors, capacitors, diodes, filters, neutral ground resistors (NGR), or other suitable electrical signal processing devices to attain desired signal characteristics for the signal20

FIG. 4is a graphical view of an embodiment of the signal20after conditioning via the negative polarity conditioning circuit32and/or the positive polarity conditioning circuit34. In other words, the graph80shows a negative output82that may be produced at the negative out65shown as a dashed line and a positive output84that may be produced at the positive out67shown as a solid line. As previously discussed, as the signal20with a negative polarity enters the polarity channeling circuit22at initial time86, the negative switch46,70routes the signal20through the negative polarity conditioning circuit32. After processing the signal20using the negative polarity conditioning circuit32, the negative output82has an initial negative DC offset88, such as less than or equal to −0V (e.g., less than or equal to −5V, −10V, −15V, or some other suitable negative voltage). Additionally, the negative output82includes an AC signal with an amplitude92(e.g., 5V). Furthermore, because the signal20is routed to the negative polarity conditioning circuit32, the positive output84is negligible at the initial time86. At a switch time90, the polarity of the signal20is no longer negative. For example, the polarity of the signal20may change due to a disconnection of the electrical component16(e.g., transducer) that sends a negative signal, and the connection of another component (e.g., a different transducer) that sends a positive signal. Alternatively, in some embodiments, the electrical device16may alternate between a positive and negative polarity in the signal20that it sends depending on certain conditions (e.g., measured values exceeding a threshold).

After switch time20, when the signal20is positive, the negative switch46,70blocks the signal20from reaching the negative polarity conditioning circuit32. As illustrated by the graph80, the signal20is switched directly from a negative polarity to a positive polarity. However, as can be appreciated, a switching period may last some period of time causing a negligible voltage to be produced at both the positive output84and the negative output82.

Returning toFIG. 4, as the signal20gains a positive polarity at the switch time90, the positive switch48,72closes and routes the signal20to the positive polarity conditioning circuit34. Accordingly, the negative output82becomes negligible at the switch time90. The positive output84then contains a positive DC offset94, such as greater than or equal to 0V (e.g., greater than or equal to 5V, 10V, 15V, or some other suitable positive voltage). The positive output84further includes an AC component having an amplitude96.

Although the illustrated negative DC offset88and the positive DC offset94are approximately equal, other embodiments of the electrical device10may be designed to output a different DC offset for a positive and negative signals. For example, amplifier circuit50in the negative polarity conditioning circuit32may differ from the amplifier circuit50in the positive polarity conditioning circuit34to achieve an a positive output84and negative output82having differing characteristics, such as different DC offsets, AC frequencies, AC amplitudes, or other signal parameters.

FIG. 5is a flow chart view illustrating an embodiment of a method100for channeling a signal according to polarity. The method100includes receiving a signal having a negative polarity or a positive polarity (block102). In some embodiments, the signal includes an AC component and a DC component. The method100further includes determining a polarity of the DC component of the signal (block104). For example, the polarity may be determined using a gate for each polarity. In other words, a positive switch closes when the signal is positive, and a negative switch closes when the signal is negative.

The method100also includes switching a positive switch if the signal has a positive polarity that routes the signal through a positive channel (block106). In some embodiments, the positive channel is coupled to a first analysis component. As discussed above, in certain embodiments, the positive switch is switched due to a difference in voltage between the gate and a drain/source depending on whether the switch is a p-mode transistor an n-mode transistor. If the signal has a negative polarity, the method100includes switching a negative switch to route the signal through a positive channel (block108). In certain embodiments, the positive channel is coupled to a second analysis component. Certain embodiments of the method100may also include analyzing the signal with the first analysis component if the signal has a positive polarity (block110). Similarly, certain embodiments of the method100may also include analyzing the signal with the second analysis component if the signal has a negative polarity (block112).

Technical effects of the invention include routing a signal depending on the polarity of a signal without requiring user selection and/or configuration. Accordingly, the polarity channeling decreases a likelihood of connection of voltages that an electrical device is not correctly configured manually by the user. Instead, upon connection of an electrical component, the signal is routed by a polarity channeling component according to the polarity of the signal rather than relying upon manual selection. Accordingly, the likelihood of an accidental connection of an incorrect polarity is reduced, thereby reducing likelihood of damage to the system.

Moreover, by channeling the signal using a polarity of the signal, the signal can be analyzed without attenuating the signal thereby reducing a signal to noise ratio of the signal causing less accurate signals. Additionally, by channeling the signal using a polarity of the signal, the signal can be analyzed without including an analog multiplexer that is susceptible to ESD or other shock events. Furthermore, by channeling the signal using a polarity of the signal, the signal can be conditioned (e.g., amplified) without using large rail operational amplifiers that are more expensive than traditional op amps and have decreased accuracy unsuitable for many intended uses of an electrical device. In other words, by channeling the signal according to polarity, a robust design may be included that is less susceptible to ESD, improper connections, or loss of accuracy that may be present in alternative electrical devices.