Maintenance compartment for an electrical distribution board

Description

Technical field

[0001] The present invention relates to the field of electrical distribution, and more specifically relates to a drawer adapted to be inserted into an electrical panel. This drawer is specially designed to allow an operator to carry out maintenance or measurement operations safely and easily. Technological background

[0002] There is a lot of electrical equipment in an industrial facility. This electrical equipment, such as motors, transformers, pumps, or other machines, requires regular monitoring and maintenance, which involves taking electrical measurements, particularly to verify their proper functioning.

[0003] These operations are, for example, carried out directly on the equipment, which has been previously powered down and grounded (short-circuited) in order to protect the operator working on the equipment from electrical risks. Pre-grounding is done, for example, by connecting clamps to each terminal of a terminal box on the equipment. Such an operation can be difficult to implement, for example due to a lack of accessibility to the equipment's electrical connections or a lack of space, and requires that the tools used, such as connection clamps, are compatible with the equipment. Any defect in carrying out this grounding can endanger the operator. Furthermore, there is a risk that a person, uninformed about the maintenance or by accident, could re-energize the equipment while an operator is working on it.

[0004] Monitoring operations can also be carried out on the electrical connection terminals of the cables at the electrical panel, for example to carry out insulation or electrical continuity measurements. Connection tools, such as clamps, are then placed on the live terminals, causing a major risk for the operator in the event of incorrect handling. The solution of de-energizing the entire electrical panel has the disadvantage of de-energizing all the equipment powered by this electrical panel, and can therefore only be carried out, for example, during scheduled maintenance shutdowns, thus preventing necessary monitoring. This solution will therefore be avoided.

[0005] Furthermore, these various operations require mechanical handling, such as unscrewing and screwing bolts holding the connection terminals, or dismantling and reassembling protective covers, as in patent application WO2010 / 122765A1.

[0006] In the long term, such manipulations significantly increase the risk of deterioration even though these manipulations are carried out frequently for maintenance purposes.

[0007] Patent application US2008 / 258667A1 proposes a system for coordinating the installation and removal of an engine control center subunit with the connection and interruption of power, with an interlock and indicator assembly.

[0008] Patent application DE102017206863A1 shows a measuring drawer comprising measuring elements and ground contacts.

[0009] Patent DE19516327C1 also discloses a measuring drawer comprising contacts connected to measuring sockets via a switch. Presentation of the invention

[0010] The aim of the invention is to enable an operator to carry out maintenance or measurement operations safely and easily on electrical equipment on an industrial site.

[0011] For this purpose, a drawer is proposed comprising: a chassis adapted to allow the drawer to be inserted into a location in a distribution panel, a front panel closing the location of the distribution panel when the drawer is inserted into a distribution panel, downstream connection terminals intended to be connected to a load, a plurality of connectors opening onto its front panel, each of these connectors being connected to a downstream connection terminal and allowing the connection of a measuring device, in which the drawer has a selector operable from the front panel, allowing the downstream connection terminals to be connected and disconnected to an equipotential link, and defining a measurement position in which the downstream connection terminals are not connected to an equipotential link and a short-circuit position in which the downstream connection terminals are connected to the equipotential link.

[0012] The drawer according to the invention makes it possible to simplify, accelerate and secure the carrying out of measurements and maintenance operations by an operator of an industrial site. The drawer is temporarily mounted (during the measurements or intervention) in place of the power supply drawer located in the electrical panel, and makes it possible to carry out measurements directly on the front of the drawer, to be able to work in isolation from the upstream power supply coming from the electrical panel. The drawer then makes it possible to secure the equipment by short-circuiting the connection terminals and making them equipotentially connected directly from the front.

[0013] The drawer is advantageously complemented by the following characteristics, taken alone or in any of their technically possible combinations: the drawer is devoid of upstream connection terminals intended to be connected to a power supply of the electrical panel; the drawer has an insulating interface intended to face the power bars of the electrical panel; the selector is rotatable between the measurement position in which the downstream connection terminals are not connected to an equipotential connection and the short-circuit position in which the downstream connection terminals are connected to the equipotential connection;the drawer further comprises a handle on the front face, said handle being movable between a first position and a second position, the second position causing the drawer to be locked in the distribution board when the drawer is inserted into the distribution board while in the first position the drawer is free to be locked in the distribution board to allow its insertion or removal, the handle being mechanically connected to the selector so that a rotation of the handle between the first position and the second position causes a rotation of the selector between the measurement position and the short-circuit position, respectively; the handle is provided with a member for locking the rotation of said handle, configured to allow or prohibit the rotation of the handle; the handle and the selector are rotatable about two separate axes, and the handle is mechanically connected to the selector by at least one connecting rod;the drawer comprises an electrically conductive short-circuiting member connectable to an equipotential connection, and the selector comprises contact members connected to each downstream connection terminal and configured to come, by rotation of the selector, into contact with the short-circuiting member; the front panel comprises a main part mechanically connected to the chassis, and an extension fixed on one side of the front panel of the main part.;

[0014] The invention also relates to a method for measuring electrical characteristics of a load connected to the downstream connection terminals of a drawer according to the invention, when said drawer is inserted into a location in an electrical panel, said method comprising the following steps: positioning the selector in the measuring position, connecting a measuring device to at least two connectors on the front panel of the drawer, carrying out measurements of the electrical characteristics of the load, wherein the downstream connection terminals comprise phase terminals and a ground terminal, a phase connector being connected to a phase terminal and a ground connector being connected to the ground terminal: the measurement is a check for absence of voltage, and the measuring device is a voltmeter, or the measurement is an insulation resistance measurement, the two connectors are a phase connector and a ground connector, and the measuring device is an insulation tester configured to apply a voltage between the two connectors and to measure a current flowing between the two connectors to deduce an insulation resistance therefrom, or the measurement is an electrical continuity measurement, the two connectors are two phase connectors, and the measuring device is an ammeter measuring a current flowing between the two phase connectors, or the measurement is a cable search, the measuring device is configured to inject into the connectors at least one measurement signal having a particular pattern, and a detector is used to identify cables of the load in which said measurement signal passes.

[0015] The invention also relates to a method of a maintenance operation of equipment connected to the downstream connection terminals of a drawer according to the invention when said drawer is inserted into a location of an electrical panel, said method comprising the following steps: positioning the selector in the short-circuit position, connecting a measuring device to at least two connectors on the front panel of the drawer, checking for the absence of voltage, carrying out the equipment maintenance operation.

[0016] The measuring method and / or the maintenance method may comprise a step of locking the positioning of the selector using a member for locking the rotation of the handle mechanically connected to the selector. Presentation of figures

[0017] The invention will be better understood from the following description, which relates to a preferred embodiment, given as a non-limiting example and explained with reference to the appended schematic drawings, among which: there figure 1 is an overall perspective view of three-quarters front and elevation of a drawer according to a possible embodiment of the invention; figure 2 is a side view of a drawer according to a possible embodiment of the invention; the figure 3 is an enlarged view of a portion of the rear of the front face of a drawer according to a possible embodiment of the invention; figure 4 is an enlarged view of a portion of the rear of the front panel of a drawer according to a possible embodiment of the invention in which the front panel comprises several parts; the Figure 5is a close-up view of the downstream section of a drawer according to a possible embodiment of the invention, showing the selector in the connection position; the figure 6 is a close-up view of the downstream section of a drawer according to a possible embodiment of the invention, showing the selector in the safety position. figure 7 is a three-quarter front view of a drawer according to a possible embodiment of the invention, showing the handle locked horizontally with the locking member inactive; figure 8 is a three-quarter front view of a drawer according to a possible embodiment of the invention, showing the handle locked vertically with the active locking member. Detailed description

[0018] An electrical panel, also called a distribution board or distribution board, is an assembly comprising different types of equipment associated with one or more incoming electrical circuits, or loads, supplied by one or more supply electrical circuits, as well as terminals for the neutral conductor and the protective conductor. In industrial applications, an electrical panel may take the form of a cabinet accommodating power drawers which are inserted into the cabinet at dedicated locations.

[0019] A conventional power drawer includes a front panel enclosing the distribution board, a metal chassis with a rail for inserting and removing the power drawer, an upstream part including upstream connection terminals to the power supply, and a downstream part including downstream connection terminals to the load. The power drawer also accommodates electrical components such as relays, contactors or fuses, both in its downstream and upstream part.

[0020] The invention provides a drawer configured to replace a conventional power drawer in a distribution board in order to be able to carry out measurements or maintenance operations on equipment connected to this distribution board.

[0021] In reference to the Figures 1 and 2 ,A drawer according to a possible embodiment, described by way of illustrative example, comprises a frame 10 adapted to allow the insertion of the drawer into a location of a distribution board. The frame 10 is for example made of steel. The frame 10 is inserted into slides of the location of the distribution board. The frame 10 may comprise a rail 12 in order to guide the insertion or removal of the drawer from the location of the electrical panel. The frame 10 serves as a support for the other components of the drawer. The drawer comprises a front panel 14 closing the location of the distribution board when the drawer is inserted into a distribution board. The size and shape of the drawer follows the shape and size of the conventional power drawer that it replaces in the electrical panel. Preferably, however, the front panel 14 has a color distinct from that of the conventional power drawers in order to be easily identifiable.For example, the front panel 14 may be green or red when the power supply drawers are blue. Furthermore, the front panel 14 may be provided with a periphery that maintains the protection index (or "IP") of the electrical distribution board when the conventional power supply drawer is in place. The protection index of the board is as defined in the international standard IEC 60529. It may be, for example, and without limitation, an "Indice of Protection 31"; the number '31' being broken down into two figures; the first figure '3' relating to the degree of protection against the penetration of solid foreign bodies larger than 12 nm, the second figure '1' relating to the degree of protection against the penetration of water in the form of falling drops of water.

[0022] In order to maintain a seal similar to that of the conventional power drawer that it replaces, the front panel 14 of the drawer must close the opening of the location of the distribution board when the drawer is inserted into the distribution board. It is therefore necessary that the dimensions of the front panel 14 correspond to the dimensions of this opening. However, the location openings of the distribution board can have different dimensions. Rather than providing drawers with as many sizes of front panel 14 as there are sizes of location openings of the distribution board, the front panel 14 of the drawer can be composed of several separate parts secured by fixing members. With reference to the figure 4, the facade 14 can thus comprise a main part 14a mechanically linked to the chassis 10, and an extension 14b fixed on one side of the facade of the main part 14a. It is on this main part 14a that the plurality of connectors each connected to a downstream connection terminal and the selector open, which will be discussed below.

[0023] The extension 14b is fixed to the main part 14a by fixing members 15, which are here bolts. For this purpose, the main part 14a and the extension 14b may have holes configured to face each other after assembly of the extension 14b on the main part 14a, to allow the passage of the fixing members 15. The main part 14a and the extension 14b may have flanges 13a, 13b facing each other in which said holes are provided. An additional flange 13c may be provided on the internal face of the extension 14b, at a distance from the flange 13b of the extension 14b, and provided with holes allowing the passage of the fixing members 15, for holding said fixing members 15. Other solutions may be envisaged for securing the parts of the facade 14. The extension 14b could slide relative to the main part 14a, with a sliding blockage.Thanks to the extension, it is possible, from a drawer provided with a front 14 having the most common dimensions (i.e. those of the main part 14a), to modify this front 14 with the extension 14b to adapt it to locations with openings of larger dimensions, in a simple and less expensive manner than being forced to provide drawers specifically dedicated to certain particular dimensions.

[0024] Furthermore, in order to maintain the protection index, the drawer may be configured to seal the opening of the location of the distribution board, by cooperating with a sealing element such as a gasket. The sealing element may be present on the periphery of the opening of the location of the distribution board, and the front 14 of the drawer may then comprise, typically on the periphery of its internal face, a space for receiving this sealing element. This receiving space may for example be defined by a peripheral flange 13d on the internal face of the front 14 projecting towards the inside of the drawer at a distance from the edge of the internal face of the front 14, clearing the receiving space for the sealing element which will then be compressed between the periphery of the internal face of the front 14 and the flange 13d. It should be noted that this flange 13d may act as a flange 13a allowing the extension 14b to be fixed.

[0025] The drawer also includes downstream connection terminals 16 intended to be connected to a load. Typically, and as in the illustrated example, the downstream connection terminals 16 take the form of knives, that is to say flat pins, intended to be inserted into receptacles of a connection terminal block of the electrical panel to be electrically connected, via a cable-type electrical connection, to equipment forming an electrical load, such as for example a motor or a transformer. There is one downstream connection terminal 16 per phase of the electrical connection, and one downstream connection terminal 16 for the ground, also called earth or equipotential bond. Typically, an industrial installation uses a power supply with three phases, hence the presence of four connection terminals 16 in the illustrated example, with a ground terminal 16a, and three phase connection terminals 16b, 16c, 16d.

[0026] Unlike a conventional power drawer, the drawer does not have upstream connection terminals intended to be connected to a power supply of the electrical panel. Instead, the drawer has an insulating interface 18 intended to face the power bars of the electrical panel, in order to isolate the drawer from the power bars, which makes it possible to ensure the absence of power supply to the downstream connection terminals 16.

[0027] The drawer further comprises a selector 20 operable from the front panel 14 and making it possible to connect and disconnect the downstream connection terminals 16 to an equipotential connection. The selector 20 is a mechanical member making it possible to select one operating mode or another operating mode of the drawer by modifying the configuration of the drawer. The selector 20 may, for example, be a switch or a disconnector.

[0028] More specifically, the drawer comprises an electrically conductive short-circuiting member 22 connected to an equipotential connection, and the selector 20 is rotatable between a measurement position in which the downstream connection terminals 16 are not connected to the equipotential connection and a short-circuit position in which the downstream connection terminals 16 are connected, via the short-circuiting member 22, to the equipotential connection.

[0029] To do this, the drawer comprises a handle 24 on the front 14, rotatable between at least a first position and a second position. The handle 24 is located on the face of the front 14 opposite the chassis 10, so that the handle 24 is accessible from outside the electrical panel when the drawer is inserted into the distribution panel. On the figure 1 , the handle 24 is in a first vertical position, while on the figure 2 ,the handle 24 is in a second vertical position. It is of course possible to provide more than two positions for the handle 24.

[0030] The selector 20 may comprise a rod 26 extending from the front 14 to contact members of the drawer, connected to each connection terminal 16 and configured to come, by rotation of the selector 20, into contact with the short-circuiting member 22. More precisely, the rotation of the handle 24 causes the rotation of the rod 26, which causes the rotation of the contact members. As shown in the figure 3, it is possible that the handle 24 and the selector 20 (or more precisely the rod 26) are not aligned, and are therefore rotatable along two separate axes. The handle 24 can then be mechanically connected to the selector 20 by at least one connecting rod 28. In the example, the part of the handle 24 passing through the facade 14 is connected to two connecting rods 28 extending along the inner face of the facade 14. These connecting rods 28 are connected to a part 29 in an eccentric manner relative to an axis around which this part 29 rotates, the rod 26 being integral with this rotating part 29.

[0031] The distribution drawer has a plurality of connectors 30 opening onto its front panel, each of these connectors 30 being connected to a downstream connection terminal 16. There is thus a ground connector 30a connected to the ground terminal 16a, and three phase connectors 30b, 30c, 30d each connected to a phase terminal 16b, 16c, 16d. The connectors 30 pass through the front panel 14 so that the connectors 30 are accessible from outside the electrical panel when the drawer is inserted into the distribution panel, while being connected to the connection terminals 16 inside. The connectors 30 allow the connection of a measuring device. The connectors are female connectors, for example of the 4 mm type, and can for example be insulated safety sockets commonly referred to as banana connectors which can accommodate male banana plugs.In a simple manner, the connection between the connectors 30 and the downstream connection terminal 16 can be made by wires 32 directly connecting each connector 30 to its connection terminal 16, as in the example illustrated. It is also possible to provide wires connecting each connector 30 to a conductive element such as the terminals 34 connected to its connection terminal 16.

[0032] In the figures 5 And 6 , the wires 32 directly connecting each connector 30 to its connection terminal 16 and the wires 33 connecting the connection terminals 16 to terminals 34 electrically connected to the selector 20 are not shown for clarification purposes. The terminals 34 are electrically connected to the contact members 36 of the selector 20 which are rotatable. On the Figure 5 ,the selector 20 is in the measuring position, which corresponds for example to the first position of the handle 24, that is to say in the horizontal position in the examples illustrated. The contact members 36 of the selector 20 are raised, and are not in contact with the member of the short-circuiting member 22. The downstream connection terminals 16 are not connected to the equipotential connection.

[0033] In this position, the downstream connection terminals 16 are not short-circuited. It is therefore possible to measure the electrical characteristics of the equipment (motor or transformer, for example) connected to the downstream connection terminals 16 of the drawer constituting the load. It is sufficient to connect a measuring device to at least two connectors 30 of the front panel 14 of the drawer to carry out measurements. For example, the measurement may be a check for the absence of voltage, and the measuring device is a voltmeter, then connected to the ground connector 30a and successively to the various phase connectors 30b, 30c, 30d.

[0034] The measurement can also be an insulation resistance measurement. The two connectors to which the measuring device is connected are a phase connector 30b, 30c, 30d and the ground connector 30a. The measuring device is an insulation tester configured to apply a voltage between the two connectors 30 and to measure a current flowing between the two connectors 30 to deduce an insulation resistance.

[0035] The measurement can also be an electrical continuity measurement, the two connectors are two phase connectors 30b, 30c, 30d, and the measuring device is an ammeter measuring a current flowing between the two phase connectors 30b, 30c, 30d.

[0036] The measurement can also be a cable search, the measuring device is then configured to inject into the connectors 30, at least one measurement signal having a particular pattern. A detector is then used to identify cables of the load in which said measurement signal passes. The injected pattern can correspond to a signal varying in voltage or intensity, capable of generating an electromagnetic signal in the vicinity of the cables concerned in which said measurement signal passes, and the detector can remotely detect this electromagnetic signal.

[0037] On the figure 6 , following the pivoting of the handle 24 into its second position, the rotation of the rod 26 has caused the rotation of the contact members 36 of the selector 20, which by pivoting have come into contact with the short-circuiting member 22. The selector 20 is then positioned in a short-circuit position.

[0038] For example, the short-circuiting member 22 may have projecting parts 38 (one per phase and for the ground) and the contact members 36 may have a U shape whose branches are placed on each side of the projecting parts 38, so as to grip these projecting parts 38 to make electrical contact between the short-circuiting member 22 and the contact members 36 of the selector 20 which are in electrical connection with the connection terminals 16. The projecting parts 38 of the short-circuiting member 22 are electrically connected to each other, and the downstream connection terminals 16 are therefore short-circuited to each other. Since the ground terminal 16a is now connected to the three phase connection terminals 16b, 16c, 16d, the downstream connection terminals 16 are then connected to ground, i.e. to an equipotential bond.Preferably, the short-circuiting member 22 is also connected to ground, for example by its contact with the chassis 10. The short-circuiting member 22, including its projecting parts 38, is made of an electrically conductive material.

[0039] Once the downstream connection terminals 16 are connected to an equipotential bond and short-circuited, it is possible for an operator to carry out a maintenance operation on equipment connected to the downstream connection terminals 16 of the drawer in complete safety. The operator can check for an absence of voltage by connecting a measuring device such as a voltmeter to at least two connectors 30 of the front panel 14 of the drawer, then carry out the maintenance operation on the equipment.

[0040] It is preferable that the drawer cannot undergo any change in its state by accident during measurements or maintenance operations. It is therefore possible to lock the positioning of the selector 20 by using a locking member 40 of the rotation of the handle 24 mechanically connected to the selector 20, as illustrated in the figures 7 and 8 . The locking member may take the form of a metal tab 40, the depression of which is necessary to allow the rotation of the handle 24. This metal tab 40 when it projects from the handle 24 has one or more holes allowing one or more padlocks 42 to be inserted therein respectively, preventing the depression of the tab 40 and therefore the rotation of the handle 24.

[0041] Furthermore, to ensure the safety of the operator, the drawer can be locked in the distribution board, in order to prevent any accidental removal. This locking is carried out by means of the handle 24. As mentioned, the handle 24 is movable between a first position and a second position, the second position causing the drawer to be locked in the distribution board when the drawer is inserted into the distribution board while in the first position the drawer is free to be locked in the distribution board in order to allow its insertion or removal. To do this, the drawer comprises at least one member for locking the drawer in the distribution board, actuable by the handle 24.

[0042] There figure 7thus shows an example of a drawer with the handle 24 in the first position, here the horizontal position, locked by a padlock 42 passed through the hole in the tongue 40. The locking member comprises at least one locking arm 44 integral with the rotation of the handle 24, which extends along the chassis 10 by a shaft on which the locking arm 44 is mounted. On the figure 7 , the locking arm 44 is raised, not extending beyond the rails 12, and allowing the drawer to be inserted. Similarly, fingers 46 are mounted on the shaft and are raised.

[0043] There figure 8shows an example of a drawer with the handle 24 in the second position, here the vertical position, locked by a padlock 42 passed through the hole in the tab 40. The locking arm 44, which has pivoted with the handle, now projects beyond the plane defined between the two rails 12, and by cooperation with the frame of the electrical panel, opposes the withdrawal of the drawer. The fingers 46 have also pivoted, and then engage with the electrical power supply bars of the panel (not shown). The fingers 46, and preferably the locking arm 44 are made of insulating material such as plastic, making it possible to electrically isolate the drawer from the power supply bars while at the same time stiffening the holding of the drawer in its location. Similarly, the interface 18 is insulating and further isolates the drawer from the power supply bars, which makes it possible to ensure the absence of electrical power to the downstream connection terminals 16.Furthermore, the assembly 18 may form a guide for the rod 26.

[0044] The invention is not limited to the embodiment described and shown in the attached figures. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention, which is defined in the claims.

Claims

1. A drawer comprising: - a chassis (10) adapted to enable insertion of the drawer in a location of a distribution switchboard, - a front panel (14) closing the location of the distribution switchboard when the drawer is inserted into a distribution switchboard, - downstream connection terminals (16) for connection to a load, - a plurality of connectors (30) opening onto its front panel (14), each of these connectors being connected to a downstream connection terminal (16) and enabling connection of a measurement device, wherein the drawer has a selector (20), the selector (20) being actuatable from the front panel (14), characterised in that the selector enables the downstream connection terminals (16) to be connected to and disconnected from an equipotential bonding and defines a measurement position wherein the downstream connection terminals (16) are not connected to an equipotential bonding and a short-circuit position wherein the downstream connection terminals (16) are connected to the equipotential bonding.

2. The drawer according to claim 1, wherein the drawer has no upstream connection terminals for connection to a power supply of the electrical distribution board.

3. The drawer according to claim 2, having an insulating interface (18) for facing the power bars of the electrical distribution board.

4. The drawer according to any of the preceding claims, wherein the selector (20) is rotatable between a measurement position in which the downstream connection terminals (16) are not connected to an equipotential bonding and a short-circuit position in which the downstream connection terminals (16) are connected to the equipotential bonding.

5. The drawer according to the preceding claim, further comprising a handle (24) on the front panel (14), said handle being movable between a first position and a second position, the second position causing the drawer to be blocked in the distribution switchboard when the drawer is inserted into the distribution switchboard whereas in the first position the drawer is free from blocking in the distribution switchboard in order to enable its insertion or removal, the handle (24) being mechanically connected to the selector so that rotation of the handle (24) between the first position and the second position causes rotation of the selector (20) between the measurement position and the short circuit position, respectively.

6. The drawer according to the preceding claim, wherein the handle (24) is provided with a member (40) for locking rotation of said handle (24) configured to authorise or prohibit rotation of the handle (24).

7. The drawer according to any of claims 1 to 6, wherein the handle (24) and the selector (20) are rotatable about two distinct axes, and the handle (24) is mechanically connected to the selector (20) by at least one connecting rod (28).

8. The drawer according to any of claims 1 to 6, wherein the drawer comprises an electrically conductive short-circuiting member (22) connectable to an equipotential bonding, and the selector (20) comprises contact members (36) connected to each downstream connection terminal (16) and configured to contact the short-circuiting member (22) by rotating the selector (20).

9. The drawer according to any of the preceding claims, wherein the panel (14) comprises a main part (14a) mechanically connected to the chassis (10), and an extension (14b) fastened to a panel side of the main part (14a).

10. A method for measuring electrical characteristics of a load connected to the downstream connection terminals (16) of a drawer according to any of claims 1 to 9, when said drawer is inserted into a location of an electrical distribution board, said method comprising the following steps of: - positioning the selector (20) in a measurement position, - connecting a measurement device to at least two connectors (30) of the front panel (14) of the drawer, - performing measurements of electrical characteristics of the load, wherein the downstream connection terminals (16) comprise phase terminals (16b, 16c, 16d) and a ground terminal (16a), a phase connector (30b, 30c, 30d) being connected to a phase terminal (16b, 16c, 16d) and a ground connector (30a) being connected to the ground terminal (16a): - the measurement is a check for the absence of voltage, and the measurement device is a voltmeter, or - the measurement is an insulation resistance measurement, the two connectors are a phase connector (30b, 30c, 30d) and a ground connector (30a), and the measuring apparatus is an insulation tester configured to apply a voltage across both connectors and to measure current flowing between both connectors to deduce an insulation resistance therefrom, or - the measurement is an electrical continuity measurement, both connectors are two phase connectors (30b, 30c, 30d), and the measurement device is an ammeter measuring current flowing between the two-phase connectors (30b, 30c, 30d), or - the measurement is a cable search, the measuring apparatus is configured to inject at least one measurement signal having a particular pattern into the connectors (30), and a detector is used to identify cables of the load in which said measurement signal is passing.

11. A method of a maintenance operation of equipment connected to the downstream connection terminals (16) of a drawer according to any of claims 1 to 9 when said drawer is inserted into a location of an electrical distribution board, said method comprising the following steps of: - positioning the selector (20) in a short-circuit position, - connecting a measurement device to at least two connectors (30) of the front panel (14) of the drawer, - checking for the absence of voltage, - performing the maintenance operation on the equipment.

12. The method according to any of claims 10 or 11, comprising a step of locking the positioning of the selector (20) using a member (40) for locking rotation of the handle (24) mechanically connected to the selector (20).