Fault current protective switch

Abstract

 A fault current protective switch that is independent of voltage, in which is a switch component (8), which operates especially as a contact element, switch element and tripping element, for measuring the fault current of the control and measuring circuit and for controlling the switch component, as well as a tuning pushbutton for tuning and a testing pushbutton for testing the fault current protective switch, in which control and measuring circuit is a fault current current transformer (7), such as a sum current transformer, and which fault current protective switch contains a casing, in which is a casing part (base part) and a lid part. In the invention at least the fault current transformer (7) is fitted into the space arranged beside the switch component (8), especially to minimize the height of the fault current protective switch.

Description

Field of technology

[0001] The object of the invention is a fault current protective switch.

[0002] More particularly the object of the invention is a fault current protective switch that is independent of voltage, in which is a switch component, which operates especially as a contact element, switch element and tripping element, for measuring the fault current of the control and measuring circuit and for controlling the switch component, as well as a tuning pushbutton and testing pushbutton for testing the fault current protective switch,
in which the control and measuring circuit contains a fault current current transformer, such as a sum current transformer, and
in which the fault current protective switch contains a casing, in which is a casing part and a lid part.

[0003] The fault current protective switch is a sensitive protective device, which in dangerous operating conditions supplements the protection provided by fuses. The fault current protective switch trips to de-energize the current circuit quickly, if the start of an insulation fault occurs in electrical equipment or electrical wires, which could produce leakage current that is dangerous to a person. An ordinary fuse is not able to detect and trip this kind of small current defect. At the moment when the amount of fault current reaches a dangerous limit or exceeds it (the tripping current is in the range of a few tens of mA, typically 30 mA), the fault current protection disconnects the current supply very quickly (in fractions of a second). Thus even in the worst fault situation a person only receives a small electric shock before the current disconnects. Fault currents can travel to ground also in other ways than through people or animals, e.g. as surface discharge currents in parts of the building. In this case there is always the risk of a fire.

[0004] The fault current protection operates as follows: When the electrical device functions normally, the electric current going into it and coming out of it is of the same magnitude. Differences between the ingoing and outcoming electric current arises when a fault current phenomenon occurs. The fault current protective switch monitors the amount of current entering the electrical device and leaving it. As long as these amounts are of the same magnitudes the passage of the electric current is unimpeded. If a part of the electric current travels to earth as fault current, the fault current protective switch then detects a difference between the incoming and outgoing current amounts. At the moment when the amount of fault current reaches a dangerous limit or exceeds it, the current supply is disconnected. The fault current protective switch contains a switch that controls a magnetic tripping device or an electronic relay that corresponds to it.

[0005] Prior art fault current protective switches are available as versions for installation in an electric board, built into a socket, for installation between the socket and the load, and built into an extension cable.

[0006] There are two types of fault current protection, voltage-dependent and voltage-independent.

[0007] A voltage-independent fault current protector only trips in a fault current situation, but the controllable output contact does not open in conjunction with e.g. a voltage outage, and thus does not need to be re-tuned when the voltage has returned. Fault current protection can be used e.g. to protect the sockets of a freezer. The device connected to the socket operates normally when the voltage has returned.

[0008] A voltage-dependent fault current protector also trips only in a fault current situation, but the controllable output contact opens in conjunction with e.g. a voltage outage, and thus requires re-tuning of the fault current protector when the voltage has returned. This kind of fault current protector cannot be used e.g. to protect the sockets of a freezer. The device connected to the socket does not operate normally when the voltage has returned.

[0009] Voltage-dependent models can be made to be substantially smaller in size than voltage-independent models, but their use is more restricted as is described above.

Prior art

[0010] A voltage-independent prior-art fault current protective switch is presented in Fig. 1 a and a cross-section A - A in Fig. 1 b. The prior-art appliance contains a base part (casing part) 1 that is round in cross-section and a lid part 2, as well as a sheet metal installation frame 3 remaining between them, in which are fixing holes 4 for the case fitting. In addition it contains a main/tuning lever 5 fitted inside the casing, which contains a metallic main/tuning shaft 13, a testing pushbutton 6, and a sum current transformer coil 7 as well as a contact element, switch element and tripping element (component 8), which is controlled with a tripping relay 22, as well a diode packet 20 and a bulk resistor 21, in which the components of the control and measuring circuit are disposed on top of the element 8.

[0011] In prior-art fault current protectors, which have a fault current protection function that is independent of voltage, the physical size of the device in question, in particular its great height, and the construction of the device is a decisive factor in restricting their use to only some limited application locations.

Summary of the invention

[0012] The purpose of the invention is to eliminate the drawbacks of prior art and to achieve a fault current protector, which when implemented with the structure according to the invention can be installed in numerous individual as well as special appliance solutions of equipment manufacturers, such as e.g. inside the appliance, on the cover of the appliance, or outside the appliance, or installed between the supply line and the appliance.

[0013] This purpose can be achieved according to the invention by moving the sum current transformer and testing circuit of the fault current protector as well as the external diode packet of the tripping relay to the side of the equipment, into separate spaces made for them, outside the round base part according to prior art, as well as by replacing the space-consuming testing lever, the bulk resistance of the testing circuit and external diode packet of the tripping relay of a prior art appliance with components that take less space that are installed on a circuit card, in which case it is possible to move the coil of the sum current transformer of the appliance, as well as the entity located on the circuit board and formed of the testing pushbutton and the diode packet of the tripping relay as well as the bulk resistance of the measuring circuit to their own separate spaces inside the appliance.

[0014] This achieves a solution with which the physical shape of a prior art fault current protector changes and as a result is physically smaller in all its physical dimensions than now, especially in the height direction substantially shallower than prior art solutions, as well as a voltage-independent fault current protection solution that is more versatile to use.

[0015] More precisely, the fault current protector according to the invention is characterized by what is disclosed in the characterization part of claim 1.

[0016] Preferred embodiments of the invention are disclosed in the other claims.

Short description of the drawings

[0017] In the following, the invention will be described in more detail by the aid of an embodiment with reference to the attached drawings, wherein

Fig. 1 a presents a prior-art fault current protective switch and Fig. 1b a section A - A,

Fig. 2a presents a fault current protective switch according to the invention opened from above, Fig. 2b a section B - B, Fig. 2c a top view of the lid, and Fig. 2d a section C - C of the lid, and

Fig. 3 presents a fault current protective switch according to the invention viewed through the aperture in the cover of a power distribution board.

Description of preferred embodiments of the invention

[0018] The fault current protector according to the invention contains a frame, in which is a base part 9 and a lid part 10, which are magnified/elongated compared to the solution according to prior art to form a rounded end on the switch side and an angular end on the control part side such that differing from the old solution it is possible to dispose the sum current transformer coil 7 together with the measuring and control circuit in a separate space, separated by a wall 28, outside the round base part and beside the contact element, switch element and tripping element 8, in which case space is obtained in the base part also for the circuit card 12 that replaces the space-consuming testing lever 6 (Fig. 1) of the old model as well as the bulk resistance 21 (Fig. 1) and the diode packet 20 (Fig. 1) in their entirety, on which the components replacing these (testing pushbutton of the testing circuit, which is the pushbutton 25 with a microswitch installed on the circuit board, the bulk resistance 26 and the diode packet 27) are disposed. The sum current transformer coil 7 and the circuit card 12 are thus brought to the same level with the contact element, switch element and tripping element 8.

[0019] Also the main/tuning levers 5 (Fig. 1) fixed to the metallic lever shaft 13 of the main switch of the prior-art model have been replaced with only a single lever part 14.

[0020] The contact element, switch element and tripping element 8 is the same in the appliance according to the invention as in a prior-art appliance. The fault current protective switch according to the invention can be fixed to the base, or to the inside of the lid via the fixing holes 15. In the solution according to the invention, quick-clamping claws 16 have been made in the base part for the fixing of the contact element, switch element and tripping element.

[0021] In the example case the fault current protection according to the invention is installed inside an old plug fuse fuseboard, in which case its tuning and testing puhbuttons are visible and usable via the aperture of the 25 A fuseholder in the cover.

[0022] In Fig. 3 the lever 14 and the micro-pushbutton 12 of the testing circuit of the fault current protection are seen through the aperture 23 in the cover 18 of the board. The frame 17 of the fault current protective switch is also seen below the lid plate as a dotted line in the figure as well as the fixing points 15 of the fault current protector and the fixing points 24 of the central cover.

[0023] It is obvious to the person skilled in the art that the different embodiments of the invention are not limited solely to the example described above, but that they may be varied within the scope of the claims presented below. The diodes and capacitors of the testing circuit and tripping relay can be of the surface-mounted type. The partition 28 can also comprise, in addition to a curved part, a wall that acts as a divider between the transformer and the circuit card.

Claims

1. Fault current protective switch that is independent of voltage, in which is a switch component (8), which operates especially as a contact element, switch element and tripping element, for measuring the fault current of the control and measuring circuit and for controlling the switch component, as well as a tuning pushbutton for tuning and a testing pushbutton for testing the fault current protective switch,
in which the control and measuring circuit contains a fault current current transformer (7), such as a sum current transformer, and
in which the fault current protective switch contains a casing, in which is a casing part (base part) and a lid part,
characterized in that
at least a fault current transformer (7) is fitted into the space arranged beside the switch component (8), especially to minimize the height of the fault current protective switch.

2. Fault current protective switch according to claim 1 characterized in that the testing pushbutton (25) and preferably also the bulk resistance (26) of the measuring circuit is connected to a circuit card, which entity thus formed is also fitted into the space beside the switch component.

3. Fault current protective switch according to claim 1 or 2 characterized in that the diode packet of the tripping relay is connected with the testing pushbutton and the bulk resistance of the measuring circuit to the same circuit card.

4. Fault current protective switch according to claim 1, 2 or 3 characterized in that the space beside it is separated by a wall (28).

5. Fault current protective switch according to any of the preceding claims characterized in that the testing pushbutton of the testing circuit is a pushbutton with a microswitch (25) installed on a circuit card.

6. Fault current protective switch according to any one of the preceding claims characterized in that the diodes and capacitors of the testing circuit and of the tripping relay are surface-mounted models.

7. Fault current protective switch according to any one of the preceding claims characterized in that the appliance can be installed via the same fixing holes (15) so as to be either installed on the base or installed on the surface.

8. Fault current protective switch according to any one of the preceding claims characterized in that the switch component (8) of the appliance locks into position onto the base of the appliance by means of claws (16).

Drawing