Patent Publication Number: US-11662368-B2

Title: Non-contact voltage measurement with adjustable size Rogowski coil

Description:
BACKGROUND 
     Technical Field 
     The present disclosure generally relates to electrical parameter measurement devices, and more particularly, to sensor probes for electrical parameter measurement devices. 
     Description of the Related Art 
     Voltmeters are instruments used for measuring voltage in an electric circuit. Instruments which measure more than one electrical characteristic are referred to as multimeters, and operate to measure a number of parameters generally needed for troubleshooting, service, and maintenance applications. Such parameters typically include alternating current (AC) voltage and current, direct current (DC) voltage and current, and resistance or continuity. Other parameters, such as power characteristics, frequency, capacitance, and temperature, may also be measured to meet the requirements of a particular application. 
     With conventional voltmeters or multimeters that measure AC voltage, it is necessary to bring at least two measurement electrodes or probes into galvanic contact with a conductor, which often requires cutting away part of the insulation of an insulated electrical wire, or providing a terminal for measurement in advance. Besides requiring an exposed wire or terminal for galvanic contact, the step of touching voltmeter probes to stripped wires or terminals can be relatively dangerous due to the risks of shock or electrocution. A “non-contact” voltage measurement device may be used to detect the presence of alternating current (AC) voltage without requiring galvanic contact with the circuit. When a voltage is detected, the user is alerted by an indication, such as a light, buzzer, or vibrating motor. However, such non-contact voltage detectors provide only an indication of the presence or absence of an AC voltage, and do not provide an indication of the actual magnitude (e.g., RMS value) of the AC voltage. 
     A general purpose multimeter employing an internal current shunt may be limited to ten amperes maximum, for example, because of the capacity of the multimeter test leads and circuitry to carry the current. Furthermore, the multimeter generally must be protected with an internal fuse to prevent excessive current levels from flowing through the multimeter, both for safety reasons and to prevent damage to the multimeter. The difficulty in removing a blown fuse, coupled with the time and cost necessary to procure a replacement fuse, make it desirable to obtain a non-contact current measuring instrument that requires no internal fuse. 
     Clamp-on multimeters provide improved capability for measuring current over general purpose multimeters by employing an integral current clamp that senses the current in the current-carrying conductor without having to cut the current-carrying conductor or break the circuit including the current-carrying conductor. A current clamp is typically provided in the same housing with a multimeter that measures other parameters such as voltage and resistance in the conventional manner using separate test probes. The current clamp is closed around the current-carrying conductor to sense the magnetic field created by the current flow. The current clamp provides a voltage signal for measurement by the multimeter which calculates and displays the measured current level. Because there is no current shunted from the current-carrying conductor through the clamp-on multimeter, the constraint on the maximum current that may be measured has largely been eliminated. Likewise, the internal fuse has been eliminated in clamp-on multimeters. 
     In order to obtain a valid current measurement, the magnetic core in the current clamp must encircle the current-carrying conductor so that the current clamp is closed. The current clamp must be mechanically actuated to open the jaws, the current-carrying conductor inserted, and the jaws then closed around the current-carrying conductor. In tight physical spaces such as an electrical cabinet, inserting the clamp-on multimeter and using this technique to make a current measurement may be inconvenient and difficult. Moreover, the jaws must be aligned to complete the magnetic core for obtaining a valid current measurement. Clamp-on multimeters are therefore difficult to use in confined spaces and require a large physical space in which to open the jaws of the current clamp. Clamp-on multimeters also tend to be physically heavy because of the substantial amount of iron used on the magnetic core. Furthermore, high levels of current may saturate the magnetic core. The current measuring capacity of the clamp-on multimeter is accordingly limited to current levels that do not saturate the magnetic core. 
     A Rogowski coil is able to sense alternating current flowing through a conductor surrounded by the Rogowski coil. There are a number of differences between the Rogowski coil and a clamp. For example, a Rogowski coil is more flexible and has a smaller cross-section than the substantially rigid clamp of the multimeter. The Rogowski coil can accordingly be used in confined spaces that are too tight and/or too small for the clamp-type multimeter. Further, the loop of a Rogowski coil can be reshaped to surround conductors having cross-sections that the clamp cannot close around. Another difference is the greater current measuring capability of the Rogowski coil as compared to the clamp. Specifically, an air core of a Rogowski does not become saturated at levels of current that saturate the magnetic material of the cores of the clamp. 
     U.S. Pre-Grant Publication No. 2019/0346492, assigned to the assignee of the present disclosure, discloses an adjustable length Rogowski coil measurement device with non-contact voltage measurement capabilities. Modeled after the appearance of a conventional Rogowski coil, the measurement device includes a Y-shaped body having channels that are spaced apart from each other at one end and adjacent to each other at the other end. One of the channels includes a lateral opening extending between the two ends that allows a length of the Rogowski coil to be inserted into and removed from the channel. A user can grasp the ends of the Rogowski coil and pull them downward to “cinch” the loop of the Rogowski coil around an insulated conductor situated within loop. With a curved Y-shaped set of channels however, the user may experience difficulty pulling the Rogowski coil through the channels, and with the diverging spaced-apart ends of the channels directing the Rogowski coil in somewhat opposite directions, the required bend in the loop to cinch the loop around an insulated conductor may prevent a tight fit of the loop around the conductor. 
     BRIEF SUMMARY 
     Disclosed herein is a sensor probe operative to sense an electrical parameter in an insulated conductor. In various embodiments, the sensor probe may be summarized as including a body, a Rogowski coil, and a non-contact sensor. The body has a first channel and a second channel defined therein. The first channel and the second channel each have respective first and second open ends that are spaced apart from each other. Additionally, the first and second channels extend through the body approximately parallel to each other. 
     The Rogowski coil has first and second ends, in which the first end of the Rogowski coil is fixed within the first channel of the body. The Rogowski coil extends out of the first end of the first channel, passes through the first and second ends of the second channel, and loops back to the second end of the first channel where the second end of the Rogowski coil is selectively insertable into the first channel opposite the first end of the Rogowski coil. 
     The non-contact sensor is coupled to the body and is positioned between the respective second ends of the first and second channels. 
     The second channel of the body is sized and dimensioned to slidably contain a length of the Rogowski coil therein such that a first loop of the Rogowski coil is formed between the respective first open ends of the first and second channels. When the second end of the Rogowski coil is inserted into the second end of the first channel, a second loop of the Rogowski coil is formed between the respective second open ends of the first and second channels. 
     A size of an interior region within the first loop and the second loop is selectively adjustable by sliding movement of the Rogowski coil within the second channel. When the insulated conductor is situated within the second loop formed by the Rogowski coil, the non-contact sensor is operative to sense at least one electrical parameter of the insulated conductor without requiring galvanic contact with the insulated conductor. 
     Embodiments of the sensor probe may include the following features or aspects: wherein the second end of the first channel of the body includes a fastener that is operative to releasably secure the second end of the Rogowski coil within the first channel when the second end of the Rogowski coil is selectively inserted into the first channel; wherein when the second end of the Rogowski coil is selectively inserted into the second end of the first channel, sidewalls of the first channel abut the Rogowski coil and releasably secure the second end of the Rogowski coil within the first channel by an interference fit; wherein the Rogowski coil is not removable from the second channel during normal use of the sensor probe; a second non-contact sensor coupled to the Rogowski coil, wherein the second non-contact sensor is operative to sense an electrical parameter in the insulated conductor when the insulated conductor is within the second loop formed by the Rogowski coil; an interface connector operatively coupled to the non-contact sensor and the Rogowski coil, wherein the interface connector is detachably coupleable to a corresponding interface connector of a main body of a measuring device; wherein the non-contact sensor comprises at least one of a non-contact voltage sensor, a non-contact current sensor, a Hall Effect sensor, a fluxgate sensor, an anisotropic magnetoresistance (AMR) sensor, or a giant magnetoresistance (GMR) sensor; a locking mechanism operative in an open position to allow the Rogowski coil to freely slide within the second channel, and in a closed position to releasably secure the Rogowski coil and prevent sliding movement of the Rogowski coil within the second channel; and wherein the body includes an interior cavity that is sized to encompass the first loop of the Rogowski coil. 
     Also disclosed herein is a device for measuring an electrical parameter in an insulated conductor. In various embodiments, the device may be summarized as including a sensor probe as described above, and control circuitry communicatively coupleable to the non-contact sensor and the Rogowski coil. In operation, the control circuitry is configured to receive sensor data indicative of signals detected by at least one of the non-contact sensor or the Rogowski coil, and process the received sensor data to determine at least one electrical parameter of the insulated conductor. 
     In various embodiments, embodiments of the device may include the following features or aspects: a measuring instrument with a main body that contains the control circuitry; wherein the main body includes at least one interface connector, and the sensor probe is detachably connectable to the at least one interface connector of the main body; wherein the main body further includes the body of the sensor probe; wherein the control circuitry, in operation, is configured to process the received sensor data to determine a voltage in the insulated conductor; wherein the control circuitry, in operation, is further configured to process the received sensor data to determine a current in the insulated conductor; a wireless communications subsystem operatively coupled to the control circuitry, wherein in operation the wireless communication subsystem is configured to wirelessly transmit the determined electrical parameter to an external system; a display that, in operation, is configured to visually present the determined electrical parameter to a user of the device; and wherein the non-contact sensor comprises at least one of a non-contact voltage sensor, a non-contact current sensor, a Hall Effect sensor, a fluxgate sensor, an anisotropic magnetoresistance (AMR) sensor, or a giant magnetoresistance (GMR) sensor. 
     In further embodiments, a sensor probe operative to detect an electrical parameter in an insulated conductor may comprise a Rogowski coil having a first end and a second end; a body fixedly coupled to the first end of the Rogowski coil, the body comprising a channel that is sized and dimensioned to allow a length of the Rogowski coil to slidably pass through the channel and selectively adjust the size of a loop formed by the Rogowski coil when the second end of the Rogowski coil is inserted into the body, wherein the size of the loop is adjusted by way of sliding movement of the Rogowski coil relative to the body through the channel; and a non-contact sensor coupled to the body, wherein the non-contact sensor is operative to sense at least one electrical parameter in the insulated conductor without requiring galvanic contact with the insulated conductor when the insulated conductor is within the loop of the Rogowski coil. 
     The sensor probe may further comprise a locking mechanism positioned within the channel, wherein the locking mechanism is operative in an open position to allow the Rogowski coil to freely slide within the channel, and in a closed position to releasably secure the Rogowski coil and prevent sliding movement of the Rogowski coil within the channel. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG.  1    is a front, right perspective view of at least one non-limiting embodiment of an electrical parameter sensor probe that includes a body, a Rogowski coil, and a non-contact sensor. 
         FIG.  2    is a rear, right perspective view of the sensor probe of  FIG.  1   . 
         FIG.  3    is a front, right perspective view of the sensor probe of  FIG.  1   , in which a front half of the body of the sensor probe has been removed. 
         FIG.  4    is a rear, right perspective view of the sensor probe of  FIG.  1   , in which a rear half of the body of the sensor probe has been removed. 
         FIG.  5    is a rear elevation view of the sensor probe as shown in  FIG.  3   , in which the Rogowski coil is retracted within the body of the sensor probe. 
         FIG.  6    is a rear elevation view of the sensor probe as shown in  FIG.  5   , in which the Rogowski coil is extended from the body of the sensor probe. 
         FIG.  7    is a rear elevation view of the sensor probe as shown in  FIG.  6   , in which a second end of the Rogowski coil is withdrawn from the body of the sensor probe, providing access to an interior region of the Rogowski coil. 
         FIG.  8    is a rear elevation view of the sensor probe as shown in  FIG.  6   , in which an insulated conductor is positioned within the interior region of the Rogowski coil, and the Rogowski coil has been partially retracted within the body of the sensor probe. 
         FIG.  9    is a front, right perspective view of another non-limiting embodiment of an electrical parameter sensor probe that includes a body, a Rogowski coil, and a non-contact sensor. 
         FIG.  10    is a rear, right perspective view of the sensor probe of  FIG.  9   . 
         FIG.  11    is a front, right perspective view of the sensor probe of  FIG.  9   , in which a front half of the body of the sensor probe has been removed. 
         FIG.  12    is a rear, right perspective view of the sensor probe of  FIG.  9   , in which a rear half of the body of the sensor probe has been removed. 
         FIG.  13    is a front elevation view of the sensor probe of  FIG.  9   . 
         FIG.  14    is a front elevation view of the sensor probe as shown in  FIG.  13   , in which a second end of the Rogowski coil is withdrawn from the body of the sensor probe, providing access to an interior region of the Rogowski coil. 
         FIG.  15    is a front elevation view of the sensor probe as shown in  FIG.  13   , in which an insulated conductor is positioned within the interior region of the Rogowski coil. 
         FIG.  16    is a front elevation view of the sensor probe as shown in  FIG.  15   , in which the Rogowski coil has been retracted toward the insulated conductor. 
     
    
    
     In the drawings, identical reference numbers identify similar elements. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles and spaces between elements are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not necessarily intended to convey information regarding any required shape of the elements, and may have been selected solely for ease of recognition in the drawings. 
     DETAILED DESCRIPTION 
     One or more embodiments of the present disclosure are directed to an electrical parameter sensor probe and to devices and methods for measuring electrical parameters (e.g., voltage, current) in an insulated electrical conductor (e.g., insulated wire) without requiring a galvanic connection with the conductor. As described herein, an electrical parameter measurement device is configured to measure one or more electrical parameters in an insulated conductor. Such devices that do not require a galvanic connection with the conductor to measure the parameter(s) are non-contact devices. As used herein, a “non-contact” device or sensor is operative to detect an electrical parameter in an insulated conductor without requiring galvanic contact with the conductor. 
     In various embodiments, a non-contact, electrical parameter sensor probe is provided that is operative to accurately measure both current and voltage in an insulated conductor under test. The sensor probe includes a body, a Rogowski coil coupled to the body, and a non-contact sensor coupled to at least one of the body or the Rogowski coil. The size of a loop of the Rogowski coil is selectively adjustable, such that the loop may be tightened around an insulated conductor under test until the conductor is positioned adjacent to a portion of the body or Rogowski coil that includes the non-contact sensor. Thus, once the loop of the Rogowski coil is tightened, the loop helps maintain the position of the insulated conductor adjacent to the non-contact sensor to obtain accurate measurements (e.g., voltage measurements) while the Rogowski coil obtains accurate current measurements. One or more electrical parameters, such as power or phase angle, may be derived using the obtained voltage and current measurements. The measured electrical parameters may be provided to a user, e.g., via a display, or may be transmitted to one or more external systems via a suitable wired or wireless connection. 
     In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed implementations. However, a person skilled in the art will recognize that additional implementations may be practiced without one or more of these specific details, or with other methods, components, materials, etc. 
     Additionally, reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Furthermore, appearance of the phrase “in at least one embodiment” in this specification does not necessarily refer to only one embodiment. The particular features, structures, or characteristics of the various embodiments described herein may be combined in any suitable manner in yet additional embodiments. 
       FIG.  1    is a front, right perspective view of at least one non-limiting embodiment of an electrical parameter sensor probe  10  that includes a body  12 , a Rogowski coil  14 , and a non-contact sensor  20 .  FIG.  2    is a rear, right perspective view of the sensor probe  10  of  FIG.  1   . Situated along a side of the body  12  proximate to the Rogowski coil  14  is a concave saddle  16  that, together with a loop of the Rogowski coil, provides an interior region  18  in which an insulated conductor may be positioned adjacent to the non-contact sensor  20 , e.g., as shown in  FIG.  8   . 
     In some embodiments, the body  12  is comprised of two halves  12   a ,  12   b  that may be fixedly or removably coupled to each other. In the embodiment shown in  FIG.  2   , screws or other securing mechanisms are inserted through apertures  22  to secure the rear half  12   b  to the front half  12   a  of the body  12 . Projecting out of the rear half  12   b  of the body  12  is a protective shell  24  that receives a cable (not shown) usable to connect the sensor probe  10  to external equipment, such as a measuring instrument that is capable of receiving and processing measurement signals or data communicated by the sensor probe  10 . The cable may lie within a trough  26  defined in the body  12  that accommodates a close fit of the cable to the body  12 . 
     The Rogowski coil  14  is flexible and has a length that extends between a first end  50  and a second end  52 . As with conventional Rogowski coils, the Rogowski coil  14  may include a toroidal coil having a central wire surrounded by the same wire wound in a helix around a flexible, non-magnetic core and sheathed in a flexible covering. As a result, one end of the coil is taken through the coil itself and brought out the other side so that both ends of the coil are on the same side (e.g., first end  50 , second end  52 ). The ends of the coil may be electrically connected to a cable as mentioned above such that signals from the Rogowski coil  14  are sent to an external measuring instrument for processing. The non-magnetic core may include air, for example. The covering of the Rogowski coil  14  may be sufficiently rigid to protect the form of the toroidal coil, and still be sufficiently flexible to allow the Rogowski coil to be formed into a loop that is adjustable in size and shape, as discussed further below. 
     The body  12  of sensor probe  10  includes a non-contact sensor  20  (e.g., a non-contact voltage sensor) coupled thereto that operates to sense an electrical parameter (e.g., voltage) in an insulated conductor under test without requiring a galvanic connection with the conductor. Additionally or alternatively, one or more non-contact sensors may be coupled to the Rogowski coil  14  in addition to or instead of the body  12  of the sensor probe. The non-contact sensor  20  may be electrically connected to a cable such that signals from the sensor  20  are sent to the measuring instrument for processing. In various embodiments, the non-contact sensor  20  may include a non-contact voltage sensor, a non-contact current sensor, a Hall Effect element, a current transformer, a fluxgate sensor, an anisotropic magnetoresistance (AMR) sensor, a giant magnetoresistance (GMR) sensor, or other types of sensors operative to sense an electrical parameter of the insulated conductor (e.g., conductor  80  shown in  FIG.  8   ) without requiring galvanic contact. Various non-limiting examples of non-contact sensors are disclosed in U.S. Provisional Patent Application No. 62/421,124, filed Nov. 11, 2016; U.S. patent application Ser. No. 15/345,256, filed Nov. 7, 2016; U.S. patent application Ser. No. 15/413,025, filed Jan. 23, 2017; U.S. patent application Ser. No. 15/412,891, filed Jan. 23, 2017; U.S. patent application Ser. No. 15/604,320, filed May 24, 2017, and U.S. patent application Ser. No. 15/625,745, filed Jun. 16, 2017, the contents of which are incorporated herein by reference, in their entirety. 
     The sensor probe  10  may also include processing or control circuitry  28  operatively coupled to the non-contact sensor  20  and/or the Rogowski coil  14 . The processing or control circuitry  28  is operative to process sensor signals received from the sensor  20  and/or the Rogowski coil  14 , and to send sensor data indicative of such sensor signals to control circuitry in the external measuring instrument. The control circuitry  28  may additionally or alternatively include conditioning or conversion circuitry that is operative to condition or convert the signals into a form receivable by a measuring instrument, such as an analog form (e.g., 0-1 V) or a digital form (e.g., 8 bits, 16 bits, 64 bits). 
     To obtain a measurement using a non-contact voltage sensor, for example, it may be advantageous for the sensor  20  to be as close as possible to the conductor  80  under test (see  FIG.  8   ). In at least some implementations, it may also be advantageous for the conductor  80  to be positioned at a particular orientation (e.g., perpendicular) relative to the non-contact sensor  20 . With conventional Rogowski coils that have relatively large, non-adjustable loops (e.g., 10 inches, 18 inches), the Rogowski coil hangs off of a conductor under test at a point that is spaced from the body of the sensor probe. From this position, it may be difficult or impossible for a non-contact voltage sensor to obtain accurate voltage measurements of the conductor under test. As discussed further below, in one or more embodiments of the present disclosure, a loop of the Rogowski coil  14  is selectively adjustable such that, as shown in  FIGS.  8  and  16   , the loop may be tightened around the conductor  80 ,  180  to position the conductor adjacent the non-contact sensor  20 ,  120  so that an accurate measurement may be obtained. 
       FIGS.  3 - 8    depict an arrangement of components that are interior to the body  12  of the sensor probe  10 .  FIG.  3    is a front, right perspective view of the sensor probe  10  in which a front half  12   a  of the body  12  of the sensor probe has been removed, while in  FIG.  4   , a rear half  12   b  of the body  12  has been removed.  FIG.  5    provides a rear elevation view of the sensor probe  10  as shown in  FIG.  3   , in which the Rogowski coil  14  is retracted within the body  12  of the sensor probe  10 . 
     The body  12  of the sensor probe  10  includes a first channel  30  and a second channel  40 . The first channel  30  and the second channel  40  each have respective first and second open ends  34 ,  32  and  44 ,  42  that are spaced apart from each other. The first and second channels  30 ,  40  extend through the body  12  approximately parallel to each other. 
     The Rogowski coil  14  has first and second ends  50 ,  52 . The first end  50  of the Rogowski coil  14  is fixed within the first channel  30  of the body  12 . The Rogowski coil  14  extends out of the first end  34  of the first channel  30 , passes through the first and second ends  44 ,  42  of the second channel  40 , and loops back to the second end  32  of the first channel  30  where the second end  52  of the Rogowski coil  14  is selectively insertable into the first channel  30  opposite the first end  50  of the Rogowski coil  14 . The non-contact sensor  20  is coupled to the body  12  and positioned between the respective second ends  32 ,  42  of the first and second channels  30 ,  40 . 
     The second channel  40  of the body  12  is sized and dimensioned to contain a length L 1  of the Rogowski coil  14  therein such that a first loop of the Rogowski coil is formed between the respective first open ends  34 ,  44  of the first and second channels  30 ,  40 . The first channel  30  of the body  12 , being approximately parallel to the second channel  40 , may have the same length L 1  as the second channel  40 . When the second end of the Rogowski coil  52  is inserted into the second end  32  of the first channel  30 , a second loop of the Rogowski coil is formed between the respective second open ends  32 ,  42  of the first and second channels  30 ,  40 . As will be understood from the disclosure herein, the size of the first loop and the second loop is selectively adjustable by sliding movement of the Rogowski coil  14  within the second channel  40 . When an insulated conductor  80  is situated within the second loop formed by the Rogowski coil  14  (see  FIG.  8   ), the non-contact sensor  20  is operative to sense at least one electrical parameter of the insulated conductor  80  without requiring galvanic contact with the insulated conductor  80 . 
       FIG.  6    is a rear elevation view of the sensor probe  10  as shown in  FIG.  5   , in which the Rogowski coil  14  is extended from the body  12 . In  FIG.  7   , the second end  52  of the Rogowski coil  14  is withdrawn from the first channel  30 , providing a gap  70  that allows an insulated conductor  80  to access and pass into the interior region  18  of the Rogowski coil  14 .  FIG.  8    is a rear elevation view of the sensor probe  10  in which an insulated conductor  80  is positioned within the interior region  18  of the Rogowski coil  14 . Additionally in  FIG.  8   , the Rogowski coil  14  has been partially retracted within the body  12  of the sensor probe  10 , thus tightening the Rogowski coil  14  against the insulated conductor  80  and holding the insulated conductor  80  proximate to the non-contact sensor  20 . 
     In some embodiments, the second end  32  of the first channel  30  of the body  12  may include a fastener that is operative to releasably secure the second end  52  of the Rogowski coil  14  within the first channel  30  when the second end  52  of the Rogowski coil  14  is selectively inserted into the first channel  30 . Such a fastener may be a conventional fastener is used in typical Rogowski coil instruments having a detachable coil end. In other embodiments, when the second end  52  of the Rogowski coil  14  is selectively inserted into the second end  32  of the first channel  30 , sidewalls of the first channel  30  may abut the Rogowski coil  14  and releasably secure the second end  52  of the Rogowski coil  14  within the first channel  30  by an interference fit. Generally, it is expected that the Rogowski coil is not removable from the second channel  40  during normal use of the sensor probe  10 . 
     In some embodiments, the sensor probe  10  may further include a second non-contact sensor coupled to a portion of the Rogowski coil  14 . In such embodiments, the second non-contact sensor may be operative to sense an electrical parameter in an insulated conductor  80  when the insulated conductor  80  is within interior region  18  of the second loop formed by the Rogowski coil  14 . 
     In some embodiments, the sensor probe  10  may further include an interface connector operatively coupled via a cable and/or wires (e.g., extending through the protective shell  24 ) to the non-contact sensor  20  and the Rogowski coil  14 , typically by way of circuitry  28  in the sensor probe  10 . It is anticipated that such an interface connector is configured to be detachably coupleable to a corresponding interface connector of a measuring device (not illustrated) configured to receive signals and data from the sensor probe  10 . 
     In some embodiments, the sensor probe  10  may further include a locking mechanism  60  that is operative in an open position, e.g., as shown in  FIGS.  5 - 7   , to allow the Rogowski coil  14  to freely slide within the second channel  40 . As illustrated in  FIG.  6   , the locking mechanism  60  has a channel  64  that is lined up with the second channel  40 . The Rogowski coil  14  is thus able to freely slide within a channel  64  and the channel  40 . In a closed position, e.g., as shown in  FIG.  8   , a user has released the locking mechanism  60  and the locking mechanism  60  has slightly shifted outward. When the locking mechanism  60  is released, a biasing element (e.g., a spring)  62  pushes an inner sidewall of the channel  64  against the portion of the Rogowski coil  14  in the channel  6 . With the inner sidewall of the channel  64  now bearing against the Rogowski coil  14 , friction helps lock the position of the Rogowski coil  14  in place. In this manner, the locking mechanism  60  releasably secures the Rogowski coil  14  and prevents sliding movement of the Rogowski coil  14  within the second channel  40 , thus helping the Rogowski coil  14  to hold the insulated conductor  80  against the non-contact sensor  20 . 
     The body  12  of the sensor probe  10  includes an interior cavity  36  that is sized to receive and preferably encompass the first loop of the Rogowski coil  14 . The interior cavity  36  is defined by inner sidewalls  54 ,  56  within the body  12 , and laterally by inner sidewalls of the front and rear  12   a ,  12   b  of the body  12 . When an insulated conductor  80 , as depicted in  FIG.  8   , is placed within the interior region  18  of the first loop, the Rogowski coil may be tightened down on the insulated conductor  80  by sliding the Rogowski coil  14  through the second channel  40  (thus reducing the size of the inner region  18 ). In this process, the balance of the Rogowski coil  14  that has slid through the second channel  40  is received within the cavity  36 . 
       FIG.  9    is a front, right perspective view of another non-limiting embodiment of an electrical parameter sensor probe  100  that includes a body  112 , a Rogowski coil  114 , and a non-contact sensor  120 .  FIG.  10    is a rear, right perspective view of the sensor probe  100  shown in  FIG.  9   . Similar to the sensor probe  10  shown in  FIGS.  1 - 8   , the Rogowski coil  114  of the sensor probe  100  shown in  FIGS.  9 - 16    may be looped around an insulated conductor (e.g., conductor  180  shown in  FIG.  16   ) and slid through a second channel in the sensor probe  100  to tighten down the Rogowski coil  114  against the conductor  180  and hold the conductor  180  proximate to the non-contact sensor  120 . 
     With regard to  FIGS.  11 - 13   ,  FIG.  11    is a front, right perspective view of the sensor probe  110  in which a front half  112   a  of the body  112  of the sensor probe has been removed, showing the interior of the rear half  112   b  of the body, while  FIG.  12    is a rear, right perspective view in which the rear half  112   b  of the body  112  has been removed, showing the interior of the front half  112   a  of the body  112 .  FIG.  13    is a front elevation view of the sensor probe  110  shown in  FIG.  9   . 
     The sensor probe  100 , as depicted, includes a locking mechanism  160  that can be screwed toward the portion of the Rogowski coil  114  in the second channel  140  in the body  112 . When the screw  162  of the locking mechanism  160  bears against the Rogowski coil  140 , the screw  162  secures the Rogowski coil  114  in place. When the locking mechanism  160  is unscrewed, the screw  162  releases from the Rogowski coil  114  and the Rogowski coil  114  is able to freely slide within the second channel  140 . 
     In some embodiments, the body  112  is comprised of two halves  112   a ,  112   b  that may be fixedly or removably coupled to each other. In the embodiment shown in  FIG.  10   , a screw or other securing mechanism may be inserted through aperture  122  to secure the rear half  112   b  to the front half  112   a  of the body  112 . Projecting out of the side of the body  112  is a protective shell  124  that receives a cable (not shown). The cable may be used to connect the sensor probe  10  to external equipment, such as a measuring instrument, that receives and processes measurement signals or data communicated by the sensor probe  100 . 
     As with the Rogowski coil  14 , the Rogowski coil  114  is flexible and has a length that extends between a first end  150  and a second end  152 . The Rogowski coil  114  may be constructed the same as the Rogowski coil  14  described above. 
     Similar to the non-contact sensor  20 , the non-contact sensor  120  (e.g., a non-contact voltage sensor) is coupled to the body  112  within a concave saddle  116  defined in a side of the body  112 . The non-contact sensor  120  operates to sense an electrical parameter (e.g., voltage) in an insulated conductor under test without requiring a galvanic connection with the conductor. Additionally or alternatively, one or more non-contact sensors may be coupled to the Rogowski coil  114 . The non-contact sensor  120  may be electrically connected to a cable such that signals from the sensor  120  are sent to a measuring instrument for processing. In various embodiments, as with the sensor  20  previously described, the non-contact sensor  120  may include a non-contact voltage sensor, a non-contact current sensor, a Hall Effect element, a current transformer, a fluxgate sensor, an anisotropic magnetoresistance (AMR) sensor, a giant magnetoresistance (GMR) sensor, or other types of sensors operative to sense an electrical parameter of the insulated conductor (e.g., conductor  80  shown in  FIG.  8   ) without requiring galvanic contact. 
     The sensor probe  100  may also include processing or control circuitry  128  that is operatively coupled to the non-contact sensor  120  and/or the Rogowski coil  114 . The processing or control circuitry  128  is operative to process sensor signals received from the sensor  120  and/or the Rogowski coil  114 , and to send sensor data indicative of such sensor signals to control circuitry in an external measuring instrument. As with the control circuitry  28 , the control circuitry  128  may additionally or alternatively include conditioning or conversion circuitry that is operative to condition or convert the sensor signals into a form receivable by a measuring instrument, such as an analog form or a digital form. 
     It may be advantageous for the sensor  120  to be as close as possible to the conductor  180  under test (see  FIG.  16   ), and in some implementations, it may be advantageous for the conductor  180  to be positioned at a particular orientation (e.g., perpendicular) relative to the non-contact sensor  120 . With the sensor probe  100 , a loop of the Rogowski coil  114  is selectively adjustable such that, as shown in  FIG.  16   , the loop can be tightened around the conductor  180  to properly position the conductor so that an accurate measurement can be obtained. 
       FIGS.  11 - 16    depict components that are interior to the body  112  of the sensor probe  100 . The body  112  of the sensor probe  100  includes a first channel  130  and a second channel  140 . The first channel  130  and the second channel  140  each have respective first and second open ends  134 ,  132  and  144 ,  142  that are spaced apart from each other. The first and second channels  130 ,  140  extend through the body  112  approximately parallel to each other. 
     The Rogowski coil  114  has first and second ends  150 ,  152 . The first end  150  of the Rogowski coil is fixed within the first channel  130 . The Rogowski coil  114  extends out of the first end  134  of the first channel  130 , passes through the first and second ends  144 ,  142  of the second channel  140 , and loops back to the second end  132  of the first channel  130  where the second end  152  of the Rogowski coil  114  is selectively insertable into the first channel  130  opposite the first end  150  of the Rogowski coil  114 . The non-contact sensor  120  is coupled to the body  112  and positioned between the respective second ends  132 ,  142  of the first and second channels  130 ,  140 . 
     The second channel  140  of the body  112  is sized and dimensioned to contain a length L 2  of the Rogowski coil  114 . A first loop of the Rogowski coil is formed between the respective first open ends  134 ,  144  of the first and second channels  130 ,  140 . Where the first channel  130  is approximately parallel to the second channel  140 , the first channel  130  may have the same length L 2  as the second channel  140 . When the second end of the Rogowski coil  152  is inserted into the second end  132  of the first channel  130 , a second loop of the Rogowski coil is formed between the respective second open ends  132 ,  142  of the first and second channels  130 ,  140 . The size of the first loop and the second loop is selectively adjustable by sliding movement of the Rogowski coil  114  within the second channel  140 . When an insulated conductor  80  is situated within the second loop formed by the Rogowski coil  114  (see  FIG.  16   ), the non-contact sensor  120  is operative to sense at least one electrical parameter of the insulated conductor  180  without requiring galvanic contact with the insulated conductor  180 . 
       FIGS.  14 - 16    illustrate front elevation views of the sensor probe  110  in operation to receive an insulated conductor  180  into an interior region  118  of the Rogowski coil  114 . The Rogowski coil  114  may then be tightened down against the conductor  180  to hold the conductor  180  proximate to the non-contact sensor  120 , similar to the operation of the sensor probe  10  shown in  FIGS.  7  and  8   . 
     In  FIG.  14   , the second end  152  of the Rogowski coil  114  is withdrawn from the body  112  of the sensor probe  100 , providing a gap  170  that allows an insulated conductor to access the interior region  118  of the Rogowski coil  114 .  FIG.  15    depicts a front elevation view of the sensor probe  100  as shown in  FIG.  13   , in which an insulated conductor  180  is situated within the interior region  118  of the Rogowski coil  114 . 
     In  FIGS.  15  and  16   , the second end  152  of the Rogowski coil  114  has been reinserted into the first channel  130 , thus closing an upper loop of the Rogowski coil  114  around the insulated conductor  180 . A user of the sensor probe  100  may then grasp and pull on a lower portion  182  of the Rogowski coil  114 . Where the first end of the Rogowski coil  114  is fixed within first channel  130 , pulling on the lower portion  182  effectively pulls a length of the Rogowski coil  114  through the second channel  140 . The length of the Rogowski coil  114  second channel  140  until the upper loop of the Rogowski coil  114  bears against the insulated conductor  180  as shown in  FIG.  16   . In  FIG.  16   , the Rogowski coil  114  has been retracted to hold the insulated conductor  180  in place. The locking mechanism  160  may be screwed down to inward to help secure the retracted Rogowski coil  114 . 
     With the second end  152  of the Rogowski coil  114  positioned near the first end  150 , the gap between the ends of the Rogowski coil proximate to the channel  126  is minimized, which improves the accuracy of the current measurement provided by the Rogowski coil by better suppression of the influence of nearby external wires. 
     As can be seen, there are advantages to providing a sensor probe  10 ,  100  with first and second channels  30 ,  40  and  130 ,  140  that are approximately parallel to one another. As the Rogowski coil  14 ,  114  slides through the second channel  40 ,  140 , there are no curves in the channel that otherwise, by friction, may diminish the free passage of the Rogowski coil  14 ,  114  through the second channel  40 ,  140 . Locking mechanisms  60 ,  160  are more readily implemented to help hold the Rogowski coil  14 ,  114  in place once the Rogowski coil has been cinched down onto the insulated conductor  80 ,  180  under test. 
     With the sensor probe  10 , the body  12  includes a cavity  36  that receives the portion of the Rogowski coil that has passed through the second channel  40 . By maintaining this portion of the Rogowski coil  14  within the body  12 , extraneous wires may be prevented from inadvertently passing through the lower loop of the Rogowski coil (opposite to the loop that surrounds the insulated conductor  80 ), which would disrupt an accurate measurement of the conductor  80 . 
     With the sensor probe  100 , the lower loop  182  of the Rogowski coil  114  provides an arrangement that is easier for a user of the sensor probe  102  grasp the Rogowski coil  114  and pull the coil downward so as to sense the Rogowski coil onto the insulated conductor  180 . 
     Although not explicitly depicted in the drawings, the sensor probe  10 ,  100  may be communicatively coupled to a measuring instrument as mentioned above. The measuring instrument may be of any suitable form and/or function. In at least some implementations, the measuring instrument may include a main body or housing. An interface connector of the sensor probe  10 ,  100  detachably couples with a corresponding interface connector of the measuring instrument. In at least some implementations, the interface connector of the sensor probe may be configured as one of a plug and a socket, and the interface connector of the measuring instrument may be configured as the other of a plug and socket. Further, in some implementations, the sensor probe may be fixedly connected to the measuring instrument by a cable, or the sensor probe and the measuring instrument may be formed together in a single housing, such that a cable to connect them is not required. 
     The main body of the measuring instrument may include a display that presents measurement results and other information, and a user interface for inputting information such as measurement instructions or other information. The display may be a display of any suitable type, such as a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED display, a plasma display, or an e-ink display. The main body  102  may include one or more audio or haptic outputs (not shown), such as one or more speakers, buzzers, vibration devices, etc. The user interface may include any of a plurality of buttons, a touch pad, touch screen, wheel, knob, dial, and/or microphone, etc. 
     The main body of the measuring instrument may further include a power supply, such as a battery or battery pack, for supplying power to the various components of the measuring instrument and possibly also the sensor probe  10 ,  100 . Generally, the measuring instrument also includes control circuitry that controls the various operations of the combination device (sensor probe and measuring instrument), such as receiving signals from the sensor probe, determining one or more electrical parameters of an insulated conductor under measurement, and outputting measurement data (e.g., to the display). The control circuitry may include one or more processors (e.g., microcontroller, DSP, ASIC, FPGA), one or more types of memory (e.g., ROM, RAM, flash memory, other nontransitory storage media), and/or one or more other types of processing or control related components. 
     In at least some implementations, the measuring instrument may include a wireless communications subsystem such as a Bluetooth® module, a Wi-Fi® module, a ZIGBEE® module, a near field communication (NFC) module, etc. The measuring instrument may be operative to communicate wirelessly via the wireless communications subsystem with an external system, such as a computer, smart phone, tablet, personal digital assistant, etc., so as to transmit measurement results to the external system or to receive instruction signals or input information from the external system. The measuring instrument may additionally or alternatively include a wired communications subsystem, such as a USB interface, etc. 
     It should be understood that the various embodiments described above can be combined to provide yet further embodiments. To the extent that they are not inconsistent with the teachings and definitions herein, the disclosure in U.S. Provisional Patent Application No. 62/421,124, filed Nov. 11, 2016; U.S. Pat. No. 10,119,998, issued Nov. 6, 2018; U.S. Pat. No. 10,139,435, issued Nov. 27, 2018; U.S. Pat. No. 10,281,503, issued May 7, 2019; U.S. Pre-Grant Publication No. 2018/0136260, published May 17, 2018, and U.S. Pat. No. 10,352,967, issued Jul. 16, 2019, as well as U.S. Pre-Grant Publication No. 2019/0346492, published Nov. 14, 2019, are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary, to employ systems, circuits and concepts of the various patents, applications and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific implementations disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.