Method and circuit for determining dispersion of electric power towards ground in electric appliances

Abstract

An electric appliance (100) is disclosed. The electric appliance has an electric load (205), and a driving element (215) for selectively energizing/de-energizing the electric load (205). The driving element (215) has a first driving terminal (A.sub.1) coupled to a first load terminal (T.sub.1) of the electric load, a second driving terminal (A.sub.2) coupled to a first power supply terminal (T.sub.N), and a control terminal (G) for switching on/off the driving element (215) thereby allowing said selective energization/de-energization, respectively. The electric appliance also has a switching element (230) for selectively coupling a second power supply terminal (T.sub.L) to a second load terminal (T.sub.2) of the electric load (205). The electric appliance (100) further has a detection arrangement (210,220) configured for detecting a first electrical quantity (V.sub.A1) at the first driving terminal (A.sub.1), and at least one between a second electrical quantity (V.sub.T2,CL,V.sub.T2,OP) at the second load terminal (T.sub.2) and a power supply electrical quantity (V.sub.MAINS) at the second power supply terminal (T.sub.L). The detection arrangement (210,220) has a coupling element (220) coupling the first driving terminal (A.sub.1) to the second load terminal (T.sub.2), and a control unit (210) coupled to the first driving terminal (A.sub.1), and to at least one between the second load terminal (T.sub.2) and the second power supply terminal (T.sub.L). The control unit (210) is further configured for determining dispersion of electric power towards ground in the electric load (205) according to the detected electrical quantities.

Claims

1. An electric appliance comprising: an electric load; a driving element for selectively energizing and de-energizing the electric load, the driving element having a first driving terminal (A.sub.1) coupled to a first load terminal (T.sub.1) of the electric load, a second driving terminal (A.sub.2) coupled to a first power supply terminal (T.sub.N), and a control terminal (G) for switching on and off the driving element to energize and de-energize the electric load, respectively; a switching element for selectively coupling a second power supply terminal (T.sub.L) to a second load terminal (T.sub.2) of the electric load; a coupling element coupling the first driving terminal (A.sub.1) to the second load terminal (T.sub.2); and a control unit coupled to the first driving terminal (A.sub.1), and to at least one of the second load terminal (T.sub.2) and the second power supply terminal (T.sub.L), the control unit being configured for: determining a first value of a first electrical quantity (V.sub.A1) at the first driving terminal (A.sub.1); determining a second value of a second electrical quantity (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS) at one of the second load terminal (T.sub.2) and the second power supply terminal (T.sub.L); and determining, based on the first value of the first electrical quantity (V.sub.A1) and the second value of a second electrical quantity (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS), that there is dispersion of electric power towards ground in the electric load.

2. The electric appliance according to claim 1, wherein the control unit is configured for: comparing the first value of the first electrical quantity (V.sub.A1) to the second value of the second electrical quantity (V.sub.12,CL,V.sub.T2,OP, V.sub.MAINS), and determining that there is dispersion of electric power towards ground in the electric load according to a result of the comparing.

3. The electric appliance according to claim 2, wherein the determining the first value of the first electrical quantity (V.sub.A1) at the first driving terminal (A.sub.1) comprises extracting a first pick value (V.sub.A1) among values of electrical quantities at the first driving terminal (A.sub.1), wherein the determining the second value of the second electrical quantity (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS) comprises extracting a second pick value (V.sub.T2,CL,V.sub.T2,OP, V.sub.MAINS) among values of electrical quantities at one of the second load terminal (T.sub.2) and the second power supply terminal (T.sub.L), and wherein the comparing comprises comparing the first pick value (V.sub.A1) to the second pick value (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS).

4. The electric appliance according to claim 3, wherein the switching element is operable to allow and prevent electrical coupling between the second load terminal (T.sub.2) and the second power supply terminal (T.sub.L) according to a closed configuration and an opened configuration, respectively, of an appliance door, wherein the extracting the second pick value (V.sub.12,CL, V.sub.T2,OP) comprises taking a first peak value (V.sub.T2,CL) indicative of the closed configuration, or a second peak value (V.sub.T2,OP) indicative of the opened configuration.

5. The electric appliance according to claim 4, wherein in the closed configuration: said comparing comprises: comparing the first pick value (V.sub.A1) to the first peak value (V.sub.T2,CL), and said determining comprises: determining that there is dispersion of electric power towards ground in the electric load if the first pick value (V.sub.A1) exceeds the first peak value (V.sub.T2,CL) at least by a first threshold value (V.sub.TH1).

6. The electric appliance according to claim 5, wherein in the opened configuration: said comparing comprises: comparing the first pick value (V.sub.A1) to the second peak value (V.sub.T2,OP); and comparing the first pick value (V.sub.A1) to a third peak value (V.sub.MAINS) of electrical quantities (V.sub.MAINS) at the second power supply terminal (T.sub.L), and said determining comprises: determining that there is dispersion of electric power towards ground in the electric load if the first pick value (V.sub.A1) exceeds the second peak value (V.sub.T2,OP) at least by a second threshold value (V.sub.TH2) and exceeds the third peak value (V.sub.MAINS) at least by a third threshold value (V.sub.TH3).

7. The electric appliance according to claim 6, wherein in the closed configuration, the second power supply terminal (T.sub.L) and the second load terminal (T.sub.2) are substantially short-circuited to each other so that the first peak value (V.sub.T2,CL) substantially equals the third peak value (V.sub.MAINS), and in the opened configuration, the second power supply terminal (T.sub.L) and the second load terminal (T.sub.2) are substantially isolated from each other so that the second peak value (V.sub.T2,OP) is lower than the third peak value (V.sub.MAINS).

8. The electric appliance according to claim 4, wherein in the opened configuration: said comparing comprises: comparing the first pick value (V.sub.A1) to the second peak value (V.sub.T2,OP);and comparing the first pick value (V.sub.A1) to a third peak value (V.sub.MAINS) of electrical quantities (V.sub.MAINS) at the second power supply terminal (T.sub.L), and said determining comprises: determining that there is dispersion of electric power towards ground in the electric load if the first pick value (V.sub.A1) exceeds the second peak value (V.sub.T2,OP) at least by a second threshold value (V.sub.TH2) and exceeds the third peak value (V.sub.MAINS) at least by a third threshold value (V.sub.TH3).

9. The electric appliance according to claim 8, wherein: in the closed configuration, the second power supply terminal (T.sub.L) and the second load terminal (T.sub.2) are substantially short-circuited to each other so that the first peak value (V.sub.T2,CL) substantially equals the third peak value (V.sub.MAINS), and in the opened configuration, the second power supply terminal (T.sub.L) and the second load terminal (T.sub.2) are substantially isolated from each other so that the second peak value (V.sub.T2,OP) is lower than the third peak value (V.sub.MAINS).

10. The electric appliance according to claim 3, wherein said comparing comprises: comparing the first pick value (V.sub.A1) to the second pick value (V.sub.MAINS) among the electrical quantities at the second power supply terminal (T.sub.L), and said determining comprises: determining that there is dispersion of electric power towards ground in the electric load if the first pick value (V.sub.A1) exceeds the second pick value (V.sub.MAINS) at least by a threshold voltage (V.sub.TH4).

11. The electric appliance according to claim 1, wherein the driving element comprises a triac.

12. The electric appliance according to claim 1, wherein the electric load comprises an electric motor.

13. The electric appliance according to claim 1, wherein the electric appliance comprises a washing machine, a drying machine, or a washing/drying machine.

14. The electric appliance according to claim 11, wherein the electric appliance comprises a rotating drum adapted to house laundry to be washed and/or dried, and wherein the electric load comprises an electric motor for drum rotation.

15. The electric appliance according to claim 1, wherein the control unit is directly coupled to the first driving terminal (A1) such that a voltage at the first driving terminal (A1) substantially equals a voltage at a first input of the control unit, and wherein the control unit is directly coupled to at least one of the second load terminal (T2) and the second power supply terminal (TL) such that a voltage at the second load terminal (T2) substantially equals a voltage at a second input of the control unit or a voltage at the second power supply terminal (TL) substantially equals a voltage at a third input of the control unit.

16. The electric appliance according to claim 1, wherein the determining the first value of the first electrical quantity (V.sub.A1) at the first driving terminal (A.sub.1) and the determining the second value of the second electrical quantity (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS) at one of the second load terminal (T.sub.2) and the second power supply terminal (T.sub.L) are responsive to a detection of a predefined variation of a current of the driving element.

17. A method for determining whether there is dispersion of electric power towards ground in an electric appliance comprising: an electric load; a driving element for selectively energizing and de-energizing the electric load, the driving element having a first driving terminal (A.sub.1) coupled to a first load terminal (T.sub.1) of the electric load, a second driving terminal (A.sub.2) coupled to a first power supply terminal (T.sub.N), and a control terminal (G) for switching on and off the driving element to energize and de-energize the electric load, respectively; and a switching element for selectively coupling a second power supply terminal (T.sub.L) to a second load terminal (T.sub.2) of the electric load; and a control unit configured for controlling the driving element and the switching element (230), wherein the method comprises, under control of the control unit, the following steps: determining a first value of a first electrical quantity (V.sub.A1) at the first driving terminal (A.sub.1); determining a second value of a second electrical quantity (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS) at one of the second load terminal (T.sub.2) and the second power supply terminal (T.sub.L); comparing the first value of the first electrical quantity (V.sub.A1) to the second value of the second electrical quantity (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS); and determining that there is dispersion of electric power towards ground in the electric load according to a result of the comparing.

18. The method according to claim 17, wherein the determining the first value of the first electrical quantity (V.sub.A1) at the first driving terminal (A.sub.1) comprises extracting a first pick value (V.sub.A1) among values of electrical quantities at the first driving terminal (A.sub.1), wherein the determining the second value of the second electrical quantity (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS) comprises extracting a second pick value (V.sub.T2,CL,V.sub.T2,OP, V.sub.MAINS) among values of electrical quantities at one of the second load terminal (T.sub.2) and the second power supply terminal (T.sub.L), and wherein said comparing comprises: comparing the first pick value (V.sub.A1) to the second pick value (V.sub.T2,CL, V.sub.T2,OP, V.sub.MAINS).

19. The method according to claim 18, wherein the extracting the second pick value (V.sub.T2,CL, V.sub.T2,OP) comprises taking a first peak value (V.sub.T2,CL) indicative of a closed configuration of an appliance door, or a second peak value (V.sub.T2,OP) indicative of an opened configuration of the appliance door, and wherein in the closed configuration: said comparing comprises: comparing the first pick value (V.sub.A1) to the first peak value (V.sub.T2,CL), and said determining comprises: determining that there is dispersion of electric power towards ground in the electric load if the first pick value (V.sub.A1) exceeds the first peak value (V.sub.T2,CL) at least by a first threshold value (V.sub.TH1).

20. The method according to claim 19, wherein in the opened configuration: said comparing comprises: comparing the first pick value (V.sub.A1) to the second peak value (V.sub.T2,OP);and comparing the first pick value (V.sub.A1) to a third peak value (V.sub.MAINS) of electrical quantities (V.sub.MAINS) at the second power supply terminal (T.sub.L), and said determining comprises: determining that there is dispersion of electric power towards ground in the electric load if the first pick value (V.sub.A1) exceeds the second peak value (V.sub.T2,OP) at least by a second threshold value (V.sub.TH2) and exceeds the third peak value (V.sub.MAINS) at least by a third threshold value (V.sub.TH3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features and advantages of the present invention will be made apparent by the following description of some exemplary and non limitative embodiments thereof; for its better intelligibility, the following description should be read making reference to the attached drawings, wherein:

(2) FIG. 1 schematically shows an electric appliance wherein the solution according to one or more embodiments of the present invention may be applied, and

(3) FIG. 2 schematically shows a portion of a circuit system of the electric appliance according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(4) Referring now to the drawings, FIG. 1 schematically shows an electric appliance or, shortly, appliance 100, for example for domestic use (i.e., a household appliance), wherein the solution according to one or more embodiments of the present invention may be applied. The appliance 100 may for example be a washing machine (as generically illustrated in the figure, and to which reference will be made in the following by way of a non-limiting example only), a washing/drying machine or a drying machine—however, as will be best understood in the following, the principles of the present invention may also apply to any other electric appliance generally equipped with electric loads that, powered by an electric power supply, could be intrinsically subjected to phenomena of dispersion of electric power towards ground.

(5) The appliance 100 preferably comprises a substantially parallepiped-shaped cabinet 105, which encloses an inner compartment 110.

(6) The inner compartment 110 accommodates a e.g. rotating drum 115 apt to house items to be treated (such as laundry to be washed and/or dried), and accessible through an access door 120 (shown in an opened configuration) preferably provided on a front panel of the cabinet 105 for loading/unloading the items.

(7) The inner compartment 110 also accommodates, not visible in such figure, a number of well-known electronic, electro-hydraulic and/or electro-mechanical components, which form (as a whole) a circuit system allowing operation of the electric appliance 100.

(8) Hereinafter, reference will be also made to FIG. 2, which schematically shows a portion of a circuit system 200 according to an embodiment of the present invention.

(9) The circuit system 200 comprises electric loads, such has the electric load 205, allowing operation of the electric appliance 100, as well as a control unit 210 allowing (among other things) selective control of the electric loads.

(10) The electric load 205, schematically illustrated as a generic block between two load terminals T.sub.1,T.sub.2, is not limiting for the present invention. In the example at issue, the electric load 205 is a motor assembly, e.g. for drum 115 rotation, that can be selectively coupled between line T.sub.L and neutral T.sub.N terminals providing an AC electric power supply (e.g., a 230V or 125V alternating voltage at a 50 Hz or 60 Hz frequency), whereas the control unit 210 is a microcontroller/microprocessor powered by proper DC electric power supplies (e.g., 3V, 5V or 12V DC supply voltages with respect to a reference, ground voltage—for example, 0V), preferably obtained by known AC electric power supply conditioning (conditioning circuits not shown).

(11) As usual, the motor assembly 205 may comprise an electric motor (e.g., including stator and rotor, not shown), as well as a number of electrically-operated switching devices (not shown) for allowing operation thereof. Such switching devices typically comprise relays adapted to switch electric motor configuration (so as to allow rotation thereof according to different directions).

(12) The circuit system 200 further comprises a driving element 215 (e.g., a triac) adapted to allow selective energization/de-energization of the motor assembly 205. The triac 215 comprises a first driving (anode) terminal A.sub.1 coupled to the load terminal T.sub.2 of the motor assembly 205 (preferably, through resistive coupling 220) and to the load terminal T.sub.1 (preferably, directly), a second anode terminal A.sub.2 coupled to the neutral terminal T.sub.N (preferably, through a further resistive coupling 225), and a gate terminal G coupled to the control unit 210 for receiving a control signal (not shown). According to well known electronic principles, the triac 215 is switched on/off (thus, causing energization/de-energization of the motor assembly 205, respectively) depending on a value of the control signal.

(13) The circuit system 200 also comprises a door lock device 230, provided between the line terminal T.sub.L and the motor assembly 205 (i.e., the load terminal T.sub.2 thereof), and acting as security means for preventing the motor assembly 205 (and/or any other electric loads downstream the door lock device 230) from being operated while the door 120 is open, and for preventing door 120 opening during operation of the motor assembly 205 (and/or of any other electric loads downstream the door lock device 230).

(14) The door lock device 230 preferably comprises a mechanical, electromechanical or magnetic switch whose switching on/off is controlled by (e.g., a further control signal, not shown, from) the control unit 210—possibly, by energization/de-energization provided by a further triac, not shown. Switching on of the door lock device 230 (closed configuration of the door 120) causes line terminal T.sub.L/load terminal T.sub.2 electric coupling, whereas switching off of the door lock device 230 (opened configuration of the door 120) causes line terminal T.sub.L/load terminal T.sub.2 electric decoupling.

(15) Operation of the circuit system 200 being relevant for understanding aspects of the present invention may be summarized as follows.

(16) In the opened configuration, the triac 215 and the door lock device 230 are both off (as the respective control signals from the control unit 210 so impose), thus no electric current flows across the motor assembly 205. In terms of electrical quantities (e.g., voltages), line T.sub.L and neutral T.sub.N terminals oscillate at Mains supply voltage (hereinafter referred to as voltage V.sub.MAINS), whereas load terminal T.sub.2, due to line terminal T.sub.L/load terminal T.sub.2 electric decoupling, is at a voltage V.sub.T2,OP (e.g., having same frequency as, but lower amplitude range than, voltage V.sub.MAINS) indicative of the opened configuration. Due to anode terminal A.sub.1/load terminal T.sub.2 and to anode terminal A.sub.2/neutral terminal T.sub.N electric couplings, a voltage drop depending on V.sub.MAINS and V.sub.T2,OP is provided across the triac 215.

(17) In the closed configuration, the triac 215 and the door lock device 230 are both on (as the respective control signals from the control unit 210 so impose). As before, line terminal T.sub.L is at the voltage V.sub.MAINS, whereas load terminal T.sub.2, due to line terminal T.sub.L/load terminal T.sub.2 electric coupling, will rise to a voltage V.sub.T2,CL (e.g., substantially equal to the voltage V.sub.MAINS) indicative of the closed configuration—as should be readily understood, the voltage V.sub.T2,CL will be closer to the voltage V.sub.MAINS the more the “transfer function” between the line terminal T.sub.L and the load terminal T.sub.2 is close to one. Due to anode terminal A.sub.1/load terminal T.sub.2 and anode terminal A.sub.2/neutral terminal T.sub.N electric couplings, a voltage drop depending on V.sub.MAINS and V.sub.T2,CL is provided across the triac 215, which generates an electric current (not shown) driving the electric motor 205.

(18) According to aspects of the present invention, the control unit 210 is coupled to the anode terminal A.sub.1 and, depending on the implementation, to the load terminal T.sub.2 and/or to the line terminal T.sub.L (and possibly to the anode terminal A.sub.2, connection shown in dash-and-dot line, as will be discussed below), for taking corresponding electrical quantities therefrom. Thus, the control unit 210 acts, together with the (resistive) coupling element 220, as a detection arrangement for detecting the voltage at the anode terminal A.sub.1, or voltage V.sub.A1, and depending on the implementation, the voltage V.sub.T2,OP/V.sub.T2,CL and/or the voltage V.sub.MAINS (and, possibly, a triac 215 current).

(19) Upon said detection, the control unit 210 compares the voltage V.sub.A1 to at least one between the voltage V.sub.T2,OP/V.sub.T2,CL and the voltage V.sub.MAINS, and determines/infers dispersion of power towards ground in the motor assembly 205 according to a result of such comparison.

(20) Preferably, the control unit 210 extracts (e.g., at each predefined time slot) pick values of the detected voltages (namely, the voltage V.sub.A1, the voltage V.sub.T2,OP/V.sub.T2,CL and/or the voltage V.sub.MAINS), and performs said comparisons by using the extracted pick values—i.e., the control unit 210 compares the peak value of voltage V.sub.A1 (or peak value V.sub.A1) to at least one between the peak value of the voltage V.sub.T2,OP/V.sub.T2,CL (or peak value V.sub.T2,OP/V.sub.T2,CL, respectively) and the peak value of the voltage V.sub.MAINS (or peak value V.sub.MAINS). This allows obtaining reliable and quick comparisons, thus easy and responsive results.

(21) The predefined time slot can be set according to specific requirements. However, in the exemplarily considered arrangement, the voltages V.sub.T2,OP/V.sub.T2,CL and V.sub.MAINS are all alternated voltages at the same Mains frequency, thus a time slot corresponding to a period (or sub-period) of the Mains frequency is preferably set.

(22) According to an embodiment of the present invention, the control unit 210 determines/infers dispersion of electric power towards ground if, in the closed configuration:
V.sub.A1+V.sub.TH1≥V.sub.T2,CL  (I)

(23) i.e., if the peak value V.sub.A1 of the voltage V.sub.A1 exceeds the peak value V.sub.T2,CL of the voltage V.sub.T2,CL at least by a predefined threshold value V.sub.TH—the threshold value V.sub.TH1 denoting the desired sensibility which the control unit 210 is required to be provided with for determining the dispersion of electric power towards ground.

(24) According to an embodiment of the present invention, the control unit 210 determines dispersion of electric power towards ground if, in the opened configuration:

(25) $\begin{array}{cc}\{\begin{array}{c}{\underset{\_}{V}}_{A1}+V_{\mathrm{TH}2}>{\underset{\_}{V}}_{\mathrm{MAINS}}\\ {\underset{\_}{V}}_{A1}+V_{\mathrm{TH}3}>{\underset{\_}{V}}_{T2,\mathrm{OP}}\end{array}& \left(\mathrm{II}\right)\end{array}$

(26) i.e. if the peak value V.sub.A1 of the voltage V.sub.A1 exceeds the peak value V.sub.MAINS of the voltage V.sub.MAINS at least by a predefined further threshold value V.sub.TH2 and the peak value V.sub.T2,OP of the voltage V.sub.T2,OP at least by another predefined threshold value V.sub.TH3—the threshold values V.sub.TH2 and V.sub.TH3 denoting, as before, the desired sensibility for determining the dispersion of electric power towards ground.

(27) Without losing of generality, the threshold values V.sub.TH2 and V.sub.TH3 may have same, similar or different values with respect to each other, as well as with respect to the threshold value V.sub.TH1.

(28) According to another embodiment of the present invention, the control unit 210 detects only the voltage V.sub.A1 and the voltage V.sub.MAINS, and extracts only the pick value V.sub.A1 and the pick value V.sub.MAINS, respectively. This can occur, for example, when detection of the voltage V.sub.T2,OP/V.sub.T2,CL is not required (as due to cost reduction) or possible (e.g., due to monitoring errors). In such scenario, the control unit 210 determines/infers dispersion of electric power towards ground if, in the closed configuration:
V.sub.A1+V.sub.TH4<V.sub.MAINS  (III)

(29) i.e., if the peak value V.sub.A1 of the voltage V.sub.A1 exceeds the peak value V.sub.MAINS of the voltage V.sub.MAINS at least by a predefined further threshold value V.sub.TH4—the threshold value V.sub.TH4 denoting, as before, the desired sensibility for determining the dispersion of electric power towards ground, and according to the specific implementation, may have same, similar or different value with respect to the threshold values V.sub.TH1,V.sub.TH2,V.sub.TH3.

(30) Due to anode terminal A.sub.1/load terminal T.sub.2 electric coupling, the formulas (I), (II) and (III) also mean that dispersion of electric power towards ground of the motor assembly 205 can be determined/inferred according to the current voltage drop across the motor assembly 205. Such formulas (I), (II) (III) have valid basis: motor assembly 205 voltage drop under normal conditions is expected to vary over nominal values when dispersion phenomena affect it. Anyway, as voltage drop variations of the motor assembly 205 also affect the current that is expected to pass through the triac 215, and typically the triac 215 current is a measure already available for other purposes (e.g., for monitoring triac operation), dispersion of electric power towards ground could also be determined based both on the formulas (I), (II) (III) and the triac 215 current. By way of example only, detection of the voltages V.sub.A1, V.sub.MAINS and/or V.sub.T2,OP/V.sub.T2,CL, as well as corresponding extraction of the pick values V.sub.A1, V.sub.MAINS and/or V.sub.T2,OP/V.sub.T2,CL thereof and following comparison based on the formulas (I), (II) (III) could be performed only upon detection of predefined variations of triac 215 current. As should be readily understood, this would allow reducing processing burden of the control unit, as the heaviest operations (i.e., detection of voltages V.sub.A1, V.sub.MAINS and/or V.sub.T2,OP/V.sub.T2,CL, extraction of the pick values V.sub.A1, V.sub.MAINS and/or V.sub.T2,OP/V.sub.T2,CL and comparison therebetween) are performed only when necessary.

(31) As soon as one of the formulas (I), (II) or (III) is verified, the control unit 210 determines/infers dispersion of electric power towards ground in the motor assembly 205, and performs corresponding safety operations (e.g., alert signaling, motor assembly 205 quick halting, triac 215 and/or door lock device 230 switching off).

(32) As should be readily understood, the dispersion of electric power towards ground so inferred is irrespective of the dispersion cause (which makes the proposed solution very advantageous over prior arts focusing on sensing of a certain electrical quantity despite of other ones), and of dispersion direction (for example, in case of a leakage current, irrespective of whether it leaks towards line terminal T.sub.L or neutral terminal T.sub.N).

(33) Naturally, in order to satisfy local and specific requirements, a person skilled in the art may apply to the solution described above many logical and/or physical modifications and alterations. More specifically, although the present invention has been described with a certain degree of particularity with reference to preferred embodiments thereof, it should be understood that various omissions, substitutions and changes in the form and details as well as other embodiments are possible. In particular, different embodiments of the invention may even be practiced without the specific details (such as the numeric examples) set forth in the preceding description for providing a more thorough understanding thereof; on the contrary, well known features may have been omitted or simplified in order not to obscure the description with unnecessary particulars. Moreover, it is expressly intended that specific elements and/or method steps described in connection with any disclosed embodiment of the invention may be incorporated in any other embodiment as a matter of general design choice.

(34) Moreover, analogous considerations apply if the electric appliance has a different structure or comprises equivalent components, or it has other operating features. In any case, any component thereof may be separated into several elements, or two or more components may be combined into a single element; in addition, each component may be replicated for supporting the execution of the corresponding operations in parallel. It should also be noted that any interaction between different components generally does not need to be continuous (unless otherwise indicated), and it may be both direct and indirect through one or more intermediaries.

(35) Moreover, although in the present description explicit reference has been made to a triac, this should not be construed limitatively. Indeed, any driving element (intended in its widest meaning of any group of electric, electro-mechanic and/or electronic components carrying out functions related to the driving of the electric load) can be used for determination of dispersion phenomena.

(36) A plurality of different or equivalent electric loads can be provided, each one individually and selectively controlled/driven by means of additional switching/driving elements (e.g., properly controlled by the control unit, or by dedicated processing/control units). However, in case of many electric loads, shared switching/driving elements may be provided.

(37) The switching elements are not necessarily relays, but also, for example, electronic switches such as power (BJT, MOS, and the like) transistors, as well as they can be in any number. Moreover, the arrangement of the switching elements herein described is not strictly necessary, and several modifications are possible; in this respect, the switching elements may be arranged and/or distributed differently in the circuit system.

(38) As should be readily understood, detection of the electrical quantities can be implemented in any useful way. For example, it is possible to provide sensing resistors (e.g., arranged in series or parallel configurations), and/or other electric elements, for example according to the provided electrical quantity to be detected. Indeed, the electrical quantities may comprise voltages (as exemplarily described in the present description), and/or currents. In this respect, current mirrors for taking such currents and properly processing it can also be provided within the control unit (or external thereto).

(39) Although in the present description explicit reference has been made to a motor assembly, this should not be construed limitatively. Indeed, the principles of the present invention for determining dispersion of electric power towards ground also apply to other electric loads downstream the door lock device, such as heating elements for causing treatment fluids (e.g., water-based cleaning solutions, rinsing water and/or air) to be heated, electro-hydraulic components (such as valves for causing the treatment fluids to be loaded and discharged during the washing/drying cycle), pumps, compressors, and the like.

(40) Finally, the solution according to an embodiment of the invention lends itself to be implemented through an equivalent method (by using similar steps, removing some steps being not essential, or adding further optional steps); moreover, the steps may be performed in different order, concurrently or in an interleaved way (at least partly).