FR2746925A1 - Sensor system for measuring electric current and voltage esp. for medium voltage conductor and ohmic voltage divider for voltage measurement also capacitive voltage divider - Google Patents

Abstract

The ohmic voltage divider (5) and the capacitive voltage divider (6) for the voltage testing are arranged together in a combination unit (1) along with the prim. conductor (4) and the current sensor (3). The sensor, the prim. conductor and the two dividers are cast in a block of casting resin.The current sensor is designed as an inductive current sensor with a wire coil (7) arranged around the prim. conductor. The prim. conductor is designed U shaped in the combination unit, and both its ends are led through on the upper side of the combination unit

Description

The invention relates to a sensor device for

  measure current and voltage, especially in ins-

medium voltage installations.

  In known sensor devices of this type, the intensity sensor and the voltage sensor are separate devices housed in different housings. These boxes have dimensions and connections on the current conductor of a medium voltage installation, defined by standard DIN 42 600 to allow their easy mounting.

  in medium voltage installations.

  However, the disadvantage of these devices is that they have to mount and connect two separate devices to

  intensity and voltage measurements.

  According to document DE 40 10 576 A1, there is known a

  sensor device with a medium voltage current converter comprising a primary winding and a winding

  secondary secondary provided with an iron core, these windings and a capacitive voltage divider being embedded, in a housing, with cast resin. The known sensor device pre-20 has the disadvantage of not being able to perform a voltage measurement.

  The object of the present invention is to create an arrangement

  sensor sitive for measuring the intensity and voltage

  sion, whose assembly and connection to a medium voltage installation are particularly simple and do not require

that little work.

  This problem is solved according to the invention by a device of the type defined above, characterized in that an intensity sensor for measuring a current in a conductor

  primary, an ohmic voltage divider to measure the voltage

  and a capacitive voltage divider for controlling

voltage in a combined device.

  The device according to the invention saves one of the two devices. The combined device is more compact than known device devices for measuring current and voltage. The assembly work is halved. At the same time, in the sensor device according to the invention, the conditions fixed by the standard are respected.

  DIN 42 600 regarding the dimensions and arrangement of the con-

  electrical tacts. This has the advantage that medium voltage installations equipped with known sensor devices can be easily transformed with a sensor device according to the invention since it suffices to simply replace the corresponding module.

  It is also advantageous if the combined device includes an intensity sensor in combination with an integrated, fixed load and a voltage divider. These two components10 supply a voltage proportional to the measured quantity. If, besides the voltage divider, a current converter had been mounted, it would be necessary, in addition to the voltage measuring device, to also provide a current measuring device, which would increase in a way the means to be implemented. Even in case of circuit

  downstream electronics, it is advantageous to use as voltages only voltages only electronic circuits

  which are customary can deal directly with, whereas in the case of a measurement quantity constituted by an intensity, it is first necessary to convert into a voltage, which requires additional circuits.

  The essential element of the invention is to use a space-saving ohmic divider instead of a convertor.

  sor of tension formed by a voluminous winding and an iron core25 because the combined apparatus respects, for its obstruction, the standards fixed to the independent apparatuses (standards DIN 42 600) and must therefore be much more compact than

separate devices.

  In combination with an ohmic voltage divider to measure the voltage, the presence of a voltage divider

  capacitive can be decisive for certain necessary applications

  additionally locating a tension control. The invention allows

  the user, by simple assembly of a single combined device

  born, and according to the needs, to carry out either a measurement of intensity, or a measurement of tension, or a control of

  voltage, or combined measurements.

  According to a preferred embodiment of the invention, the intensity sensor, the primary conductor, the ohmic voltage divider and the capacitive voltage divider

  are provided in a block embedded in the resin. These means per-

  put block electrical components and at the same time

  provide electrical insulation while performing the bol-

  tier of the device. To have a particularly high measurement accuracy and a low voltage level for intensity measurement, it is advantageous to make the sensor

  current as an inductive sensor with a coil of wire

turn of the primary conductor.

  A simple solution provides for carrying out the conduc-

  primary as a U-shaped combination device with both ends on the upper side of the combination device

have two terminals.

  The U shape of the primary conductor simplifies the connection of the device combined with the medium voltage installation according to DIN 42 600. The terminals are adapted by their arrangement, their dimensions and the connection method

  mechanical, at the medium voltage installation.

  According to another advantageous characteristic of the invention, the combined device comprises on its upper face threads for fixing screws. These threads, used for mounting the device according to the invention, may in particular be constituted by threaded sleeves also embedded in the block of cast resin forming the housing of the device. This provides a simple adaptation to DIN 42 600 without

  that this does not require complicated manufacturing means.

  According to a development of the invention, the divider

  of ohmic voltage consists of a resistor in the form of ru-

  ban and the two ends of this ribbon are surrounded by pot-shaped field dispersion electrodes. This mode of

  realization is simple to manufacture; it is particularly appropriate-

  lie well to be drowned in synthetic resin. The

  field control electrodes provide even distribution

electric field.

  One can still improve the dielectric character of the tension divider if one drowns the resistance in the form of

  ribbon in silicone gum. This means protects the divi-

  voltage tester against chemical and mechanical attacks and in particular electrical attacks. Silicone coating is particularly advantageous if the voltage divider is

  embedded in a casing of cast resin. In this case the

  the silicone forms a noble, waterproof, electrical seal,

  avoiding partial discharges at the voltage divider

  if we. According to a development of the invention, the measurement lines, connecting the current sensor to the ohmic voltage divider and to the capacitive voltage divider, are connected to a device for displaying or exploiting the measurement values which is connected to the bottom side of the handset and exits through the side of this handset. The measurement lines are advantageously grouped together and exit at a point from the housing of the combined device, where there is the greatest distance from the terminals of the current conductors conducting the

medium voltage.

  According to a preferred embodiment, the device

  positive sensor according to the invention is designed for voltages

  medium sions up to 3 kV and can be used particularly advantageously with pre-

  seen for nominal currents between 40A and 640 A, and 1250A to 2500A, the network voltage applied on the secondary side is kept constant at 150 mV and the current intensity, permanent, maximum on the thermal level, is 1250 A or

2500A.

  For the application of the invention it is recommended

  that the ohmic voltage divider characteristically presents

  teristics a 10,000/1 division ratio, the resistance of the

  primary side being about 50 MQ and 300 kQ.

  An exemplary embodiment of the invention is described below in more detail with the aid of the appended drawings in which:

  * Figure 1 is a section of the housing of a cap device

  tor according to the invention, * FIG. 2 is a side view of the same housing,

  * Figure 3 is a top view of the same housing.

  Figure 1 shows a combined device 1, cut, the housing 2 is made of cast resin. The combined device 1 includes a sensor device for measuring the current and the voltage in medium voltage installations designed for voltages up to 36 kV. An intensity sensor 3, a primary conductor 4, an ohmic voltage divider 5

  and a capacitive voltage divider 6 are embedded in the box

tier 2.

  The intensity sensor 3, used to measure

  intensity, is an inductive sensor; it consists of a bo-

  bine of wire 7 surrounding the primary conductor 4. The conductor

  primary 4 is a copper wire intended for nominal currents

  nals from 80 A to 640 A or 1250 A to 2500 A and for a permanent, maximum thermal current intensity of 1250 A or 2500 A. The primary conductor A has a U shape;

  it crosses the spool of wire 7 and arrives via its two ends

  tees at the upper face of the housing 2; at its two ends, it comprises a connection means 8 for ensuring the electrical connection with the current conductors of

the medium voltage installation.

  The combined device 1 also has on its upper face, next to the connection surfaces 8, threaded sleeves 9 intended to receive fixing screws for mounting in the medium-voltage installation. The threaded sleeves 9 are embedded in the housing 2; the dimensions of the electrical connections 8 and of the threaded sleeves 9 of the combined device 1

  correspond to DIN 42 600 standard.

  The voltage divider, ohmic 5, consists of a ribbon-shaped resistor made on a ceramic support with a printed conductor, preferably made

  with a resistant paste. The 5 pos ohmic voltage divider

  partial resistance on the primary side in the order of

  MQ at 300 Mn. This gives a division ratio of 10,000/1.

  Two field control electrodes 10 are provided at the two ends of the voltage divider 5; these electrodes ensure a passage as regular as possible from the electric field to

  voltage ohmic divider level 5.

  The voltage divider, capacitive 6, is mainly intended for monitoring purposes. It allows you to check

  proud whether or not the medium voltage installation is energized. The precise voltage measurement is carried out with the ohmic voltage divider 5.

  Measuring lines 11, 12 leave the intensity sensor 3, the ohmic voltage divider 5 and the capacitive voltage divider 6 to go to a device for displaying and processing the measured values (device not shown-10 felt). The measurement lines 11, 12 are connected to the lower side of the housing 2 and exit laterally from the device

handset 1.

NOMENCLATURE

  1. combined device 2. housing 3. current sensor 4. primary conductor 5. ohmic voltage divider 6. capacitive voltage divider 7. coil 8. connection 9. threaded sleeve 10. field control electrode 11. line measure 12. measurement line

Claims (7)

R E V E N D I C A T IONS   1) Sensor device for measuring an intensity and a voltage, in particular in medium voltage installations, characterized by an intensity sensor (3) for measuring a current in a primary conductor (4), an ohmic voltage divider (5) for   measure the voltage and a capacitive voltage divider (6) for the voltage control in a combined device (1).   2) Device according to claim 1, characterized in that   the intensity sensor (3), the primary conductor (4), the di-   ohmic voltage viewfinder (5) and the capacitive voltage divider   sion (6) are embedded in a block of cast resin, the   main dimensions preferably correspond to DIN 42600.   3) Sensor device according to claim 1 or 2, characterized in that   the intensity sensor (3) is an intensity sensor, induc-   tif, with a coil of wire (7) surrounding the primary conductor mayor (4).   4) sensor device according to one of claims 1 to 3,   characterized in that the primary conductor (4) is U-shaped in the device   combined (1) and its two ends arrive on the upper side   of the combined device (1) and have two connections (8).    ) Sensor device according to one of claims 1 to 4,   characterized in that the combined device (1) is provided on its upper surface with   threads (9) to receive fixing screws.   6) sensor device according to one of claims 1 to 5,   characterized in that the ohmic voltage divider (5) consists of a resistor   in the form of a ribbon whose two ends are surrounded by no-   particularly in the manner of a pot by the control electrodes of field (10).   ) Sensor device according to claim 6, characterized in that   the resistance divider is coated with silicone gum.   8) sensor device according to one of claims 1 to 7, characterized in that   the measurement lines (11, 12), which connect the voltage divider   ohmic voltage (5) and the capacitive voltage divider (6) to a value or operating display device, can be connected to the underside of the combined device (1)   or exit laterally from the combined device (1).   9) sensor device according to one of claims 1 to 8,   characterized in that the intensity sensor (3) is designed for nominal currents from 80 A to 640 A or 1250 A to 2500 A, the nominal voltage on the secondary side being essentially constant at 150 mV and in that the maximum permanent thermal intensity is 1250 A or 2500 A.    ) Sensor device according to one of claims 1 to 9, characterized in that   the ohmic voltage divider (5) has characteristically   a division ratio of 10,000/1, the resistance of the   high voltage side being in a range from 50 MQ to 300 kn.