FR2757700A1 - Protection mechanism for 3-phase electrical apparatus - Google Patents

Abstract

The protection mechanism has a switch circuit (20) which operates when a current sensor (26) connected across the three phase supplies senses a malfunction. One side of the current sensor is connected to an earth rail. The earth is connected via an earth wire with a plug (16) which pushes into a socket. The plug operates a switch (24) which sets the earth, allowing connection to the current sensor. The conductor protection rail (PEN,N) is also connected through this connector.

Description

 The present invention relates to a device for protecting an electrical device and for connecting said device to a polyphase supply voltage source, particularly suitable for supplying and protecting electrical devices in the aeronautical field. .

 The devices for protecting and supplying voltage to electrical devices conventionally comprise a terminal for supplying and connecting the device to a voltage source, an electrical protection circuit breaker connected to said supply terminal and intended to be connected to the voltage source, a device for controlling the operation of the circuit breaker intended to be supplied by the voltage source and adapted to cause the closing and opening of said circuit breaker, respectively in the absence and in the presence of said voltage across the terminals of said control member, and means of connection to the ground of a voltage source protection conductor.

 Such devices are for example used in workshops for maintenance of electrical devices on board aircraft for the supply and electrical protection of these devices, as well as for the protection of operators working on these devices.

 They provide relatively effective protection against overvoltages. However, they have a certain number of drawbacks, in particular due to the fact that they are not very effective when the ground connection of the voltage source and, in particular of the protective conductor, namely the neutral N or the conductor " PEN "is not performed.

 The object of the invention is to overcome these drawbacks and to provide a device for protecting and connecting an electrical appliance to a polyphase supply voltage source making it possible to provide electrical protection for the appliances and people located nearby. , and also allowing to permanently check the ground connection of the protective conductor of the supply voltage source.

 It therefore relates to a device for protecting and connecting an electrical appliance to a polyphase supply voltage source, of the aforementioned type, characterized in that said means of ground connection include a grounding plug. engaging in a terminal for connection to the voltage source protection conductor, and a switch for controlling the supply of said circuit-breaker control member, switched to closing when the plug engages in said terminal connection to the protective conductor of the voltage source.

The device according to the invention can also include one or more of the following characteristics:
- Said plug comprises a substantially tubular pin of electrically conductive material and provided with a distal end engaging in said connection terminal to the protective conductor and with a proximal end extended by a zone for gripping the plug delimiting with said pin an annular shoulder, said terminal comprising means for guiding the spindle and a stop for said shoulder;
- The device further comprises means for snapping the pin into the terminal for connection to the voltage source protection conductor;
- Said connection terminal to the protective conductor is constituted by a piece of electrically conductive material comprising a first part for mechanical fixing and electrical connection of the plug, carrying said stop and provided with a hole for guiding the pin, and d 'a second part for fixing said switch opposite said orifice so that the distal end of the pin cooperates with said switch when the shoulder is in abutment against said stop;
- Said circuit breaker control member comprises a coil intended to be supplied by said voltage source and associated with a plunger core made of magnetic material mechanically coupled to the circuit breaker and mounted axially displaceable in the coil;
- said coil is connected, in operation, between two phases of the power source
- The device further comprises an indicator light for signaling the supply of said device, connected between said circuit breaker and said control member
- The device further comprises an additional circuit breaker for protecting said device against overvoltages, connected to the input of said device
- said voltage source is a voltage source whose value is equal to 115 V, and said terminal is connected, via said circuit breaker, to one of the phases and to the protective conductor of the voltage source to deliver single-phase voltage
- said voltage source is a voltage source whose value is equal to 200 V, said connection terminal being connected, via said three-phase circuit breaker and to the protective conductor of said power source, so as to deliver a three-phase voltage.

Other characteristics and advantages will emerge from the following description, given solely by way of example and made with reference to the appended drawings in which
- Figure 1 is a general front view of the power supply and protection device according to the invention;
- Figure 2 shows the electrical circuit of the device of Figure 1
- Figure 3 is a perspective view of the ground connection terminal of the voltage source protection conductor; and
- Figure 4 shows the electrical circuit of the device of Figure 1, according to another embodiment;
In Figure 1, there is shown a general front view of the power supply and electrical protection device of an apparatus according to the invention. Such a device is intended to be used in a work station of a workshop for the maintenance of electrical equipment in the aeronautical field, for example of electrical devices on board aircraft.

 I1 enables these devices to be supplied with a supply voltage having a frequency equal to 400 Hz and a voltage equal to 115 V for a single-phase supply voltage and to 200 V for a three-phase supply voltage.

 The device represented in FIG. 1 comprises a box 10 comprising on the front a terminal 12 for supply and connection to a polyphase voltage source of a device to be tested (not shown) and a terminal 14 for connection to the ground of a voltage source protection conductor associated with a plug 16 provided with a conductor 18 connected to ground or earth.

 As will be described in detail below, this device makes it possible to provide electrical protection of the device connected to the power terminal 12 as well as protection of the operators by disconnecting the power source and the terminal 12 d 'on the one hand when the connection to earth or earth of the device is not made and, on the other hand, in the event of overvoltages.

 The electrical circuit of this device will now be described with reference to FIG. 2.

 We see in this figure that the electrical circuit of this device is connected in operation to a polyphase voltage source 17, delivering, according to a first embodiment, a voltage equal to 115 V and a frequency equal to 400 Hz, for a power supply single phase.

 It comprises a circuit breaker 20 interposed between the source 17 and the terminal 12 for connecting the device and a member 22 for controlling the operation of the circuit breaker 20 intended to cause the closing and opening of the circuit breaker 20, as will be described by after.

The circuit breaker 20 is constituted by a conventional type bipolar circuit breaker connected at the input to one of the phases P1 and to the protective conductor PEN or
N from source 17 and, at output, to supply terminal 12.

 It is for example constituted by a curved circuit breaker B of type C60N.

 Furthermore, the device 22 for controlling the circuit breaker 20 is connected between two phases P1 and P2 of the source 17 by means of a switch 24.

 It can be seen in FIG. 2 that the member 22 is constituted by a coil 26 in which is axially displaceable a plunger core 27 made of magnetic material itself mechanically coupled to the circuit breaker 20.

 The coil 26 is for example constituted by a conventional coil with no voltage, ensuring, by means of the plunger core 27, the maintenance in the closed position of the circuit breaker 20 as long as it is supplied.

 It can also be seen in FIG. 2 that the switch 24 is mounted on the terminal 14 for connecting the protective conductor PEN to the ground or to the ground in which the plug 16 engages.

 Referring also to FIG. 3, the connection terminal 14 is constituted by a metal base comprising two substantially parallelepipedic parts, 28 and 29, disposed substantially perpendicularly to one another and delimiting one zone 28 mechanical fixing and electrical connection of the plug 16 and the other 29 a fixing area of the switch 24.

 In particular, the first part 28 of the terminal 14 is provided with an orifice 30 and a cylindrical extension 32 coaxial with the orifice 30 into which a nut 34 is screwed for fixing a conductor 36 (FIG. 2 ) connected to the protective conductor N of the source 17.

 In addition, the first part 28 is provided with two transverse threaded orifices, such as 38, in each of which engages a ball 40 bearing against a spring 42 urged by a screw 44.

 It can also be seen in FIG. 3 that the second part 29 of the terminal 14 is provided with two transverse orifices 46 into which screws (not shown) are screwed for fixing the switch 24.

 The plug 16 comprises a substantially tubular pin 48 provided with a first distal end 50 engaging in the orifice 30 of the terminal 14 and with an opposite proximal end 52 extended by a gripping zone 54 of generally tubular shape and diameter greater than that of spindle 48.

 The spindle 48 and the grip zone 54 delimit between them, in the vicinity of the proximal end 52, an annular shoulder abutting the fixing nut 34, during the insertion of the plug 16 into the spindle 14.

 It can also be seen in FIG. 3 that the spindle 48 is provided with an annular groove 56 in which the balls 40 of the first part 28 of the terminal 14 engage.

 It should be noted that the dimensions of the terminal 14, and in particular the positioning of the orifices 46 for fixing the switch 24, are adapted so that the engagement in abutment of the plug 14 against the nut 34 corresponds to an action on the switch. 24.

 Referring again to FIG. 2, it can be seen that the circuit is completed by an indicator light 58 connected, on the one hand, to the coil 26 and, on the other hand, to the output of the circuit breaker 20, and by a additional bipolar circuit breaker 60 for protecting the electrical elements of the device, connected at two-phase input P1 and P2 from the power source 17 and at output at the common terminal between the indicator light 58 and the coil 26, and at the switch 24.

 To ensure the electrical supply of a device to be tested, an operator must first connect the device to the power supply terminal 12 and insert the plug 16 into the terminal 14 by snap-in until the shoulder come into abutment against nut 34.

 In this position, the distal end 50 of the pin 48 actuates the switch 24 which causes the supply of the coil 22 and thus the closing of the circuit breaker 20, this circuit breaker being closed as long as the coil 22 is supplied by the source 17 .

 Thus, if the plug 16 is not engaged or is incompletely engaged in the terminal 14, the switch 24 is no longer actuated, which causes the supply of the coil 22 to be cut off and therefore the opening of the circuit breaker 20.

 It is therefore understandable that if the protective conductor of the voltage source 17 is not connected to ground or to earth, the supply terminal 12 is disconnected from the source 17 thus avoiding any risk of incident for the personnel. .

 Likewise, when a voltage peak appears in the voltage source 17, the circuit breaker 20 opens, thereby cutting off the power supply to the device connected to the power supply terminal 12.

 It should be noted that when the circuit breaker 20 is actuated on opening, the supply can only be restored when a manual and voluntary action is carried out by an operator on the circuit breaker.

 The description of the device which has just been made allows the supply of an electrical appliance with a single-phase voltage of amplitude equal to 115 V and of frequency equal to 400 Hz.

 According to another embodiment, represented in FIG. 4, such a device also allows, as mentioned previously, the supply of an electrical appliance by means of a three-phase alternating voltage of amplitude equal to 200 V and of frequency equal to 400 Hz.

 In this case, the electrical circuit of the device differs from the circuit described with reference to Figure 2 only by the nature of the circuit breaker used.

 It can be seen in FIG. 4 that the circuit breaker 62 is a four-pole circuit breaker connected at the input to the three phases P1, P2 and P3 and to the protective conductor PEN of the power source and, at the output to the power terminal 64.

Claims (10)

 1. Device for protecting and connecting an electrical appliance to a polyphase supply voltage source, in particular a voltage source at a frequency equal to 400 Hz, said device comprising a supply terminal (12; 64) and for connecting said appliance to the voltage source (17), an electrical protection circuit breaker (20; 62) connected to said supply terminal and intended to be connected to the voltage source, an operation control member (22) of the circuit breaker (20; 62) intended to be supplied by the voltage source (17) and adapted to cause the closing and opening of said circuit breaker (20; 62), respectively in the presence and in the absence of said voltage across the terminals said control member (22) and means for connecting to the ground a protective conductor (PEN) of the voltage source (17), characterized in that said ground connection means comprise a plug (16) grounding in a terminal (14) for connection to the protective conductor (PEN, N) of the voltage source, and a switch (24) for controlling the supply of said circuit breaker control member (22), switched on closing when the plug (16) is engaged in said terminal (14) for connection to the voltage source protection conductor.  2. Device according to claim 1, characterized in that said plug (16) comprises a substantially tubular pin (18) of electrically conductive material and provided with a distal end (50) engaging in said connection terminal (14) and a proximal end (52) extended by a zone (54) for gripping the plug delimiting with said pin an annular shoulder, said terminal (14) comprising means (30) for guiding the pin and a stop (34 ) for said shoulder.  3. Device according to claim 2, characterized in that it further comprises means (40,42,44) for latching the spindle in the terminal (14) for connection to the protective conductor of the voltage source.  4. Device according to one of claims 2 and 3, characterized in that said terminal (14) for connection to the protective conductor is constituted by a piece of electrically conductive material comprising a first part (28) for mechanical fixing and connection electric plug (16), carrying said stop (34) and provided with a hole (30) for guiding the spindle, and a second part (29) for fixing said switch (24) opposite said hole ( 30) so that the distal end of the pin (18) cooperates with said switch when the shoulder is in abutment against said stop (34).  5. Device according to any one of claims 1 to 4, characterized in that said circuit breaker control member comprises a coil (26) intended to be supplied by said voltage source and associated with a plunger core (27) made of magnetic material mechanically coupled to the circuit breaker (20; 62) and mounted axially displaceable in the coil (26).  6. Device according to claim 5, characterized in that said coil (26) is connected in operation between two phases of the supply source (17).  7. Device according to any one of claims 1 to 6, characterized in that it further comprises an indicator light (58) for signaling the supply of said device, connected between said circuit breaker and said control member.  8. Device according to any one of claims 1 to 7, characterized in that it further comprises an additional circuit breaker (60) for protecting said device against overvoltages, connected at the input of said device.  9. Device according to any one of claims 1 to 8, characterized in that said voltage source (17) is a voltage source whose value is equal to 115 V, and in that said supply terminal (12) is connected, via said circuit breaker (20), to one of the phases and to the protective conductor of the voltage source so as to deliver a single-phase voltage.  10. Device according to any one of claims 1 to 8, characterized in that said voltage source is a voltage source whose value is equal to 200 V, and in that said supply terminal (64) is connected, via said circuit breaker (62) to the three phases and to the protective conductor of said power source, so as to deliver a three-phase voltage.