Abstract:
A device for electromagnetic noise reduction in a hybrid automotive vehicle includes at least one sensor that measures a conducted noise generated by at least one noise source, a reducer that reduces a radiated noise, referred to as modified, on a signal of interest made noisy by the modified radiated noise, where the reducer includes a determiner that determines the noise corrected signal of interest from a noisy signal of interest, where the determiner includes an estimator that estimates the modified radiated noise from the conducted noise, and a selector that selects a frequency for receiving a radiofrequency signal.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International Application No. PCT/JP2010/006870 filed Nov. 25, 2010, claiming priority based on French Patent Application No. 0958492 filed Nov. 30, 2009, the contents of all of which are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to electromagnetic noise reduction, especially in the automobile domain and more specifically that of hybrid vehicles. 
     BACKGROUND ART 
     Automobiles including a high-power energy converter are known. Such a converter forms a source of noise which can propagate by radiation and conduction. In fact a converter includes high switching speed electronic components which generate broadband noise. Conducted noise travels in the cables and structure of the vehicle. The radiated noise propagates as an electromagnetic wave. 
     SUMMARY OF INVENTION 
     Technical Problem 
     The radiated electromagnetic wave disturbs a signal, referred to as of interest, going to a receiving antenna of the vehicle. Thus this signal of interest is corrupted by the radiated electromagnetic noise. 
     Such a noise source leads to a comfort problem because it disturbs radio reception in the vehicle. 
     The purpose of the invention is to improve the comfort of the users of the vehicle. 
     Solution to Problem 
     To that end, the object of the invention is a device for electromagnetic noise reduction in a hybrid automotive vehicle, comprising:
         at least one sensor for measurement of a conducted noise generated by at least one noise source   a reduction unit for a radiated noise, referred to as modified, on a signal of interest made noisy by the modified radiated noise, where the reduction unit comprises means for determination of the noise corrected signal of interest from the noisy signal of interest, where the means of determination include means for estimation of the modified radiated noise from the conducted noise.       

     The device according to the invention makes it possible to cancel the noise from the signal of interest and thereby eliminate the problems related to the comfort of the users of the vehicle. Actually, the conducted noise measured by the sensor makes it possible to first estimate the radiated noise because the measured conducted noise is an image of all or part of the radiated noise. It is therefore possible to estimate the radiated noise from the conducted noise and therefore to determine the noise corrected signal of interest from the conducted noise and the noisy signal of interest. 
     Furthermore, the radiated noise can be modified by the environment of the vehicle, the frame of the vehicle, in particular. Therefore, the noise initially radiated by the noise source, called initial radiated noise, is different from the radiated noise, called modified radiated noise, which actually disturbs the receiver antenna. With the means for estimating the modified radiated signal from the conducted noise, the signal of interest is noise corrected for the modified noise actually disturbing the antenna receiving the signal of interest. 
     Furthermore, the environment modifying the initial noise has properties which are substantially constant over time and unaffected by the signals and the noise. The signal and the noise can be either quasi-stationary or even stationary or slowly varying (non-stationary). The device allows for continuously estimating a transfer function between the conducted noise and the radiated noise in order to constantly adapt to the possible variations of the environment of the device. 
     According to another optional feature, the sensor includes a Rogowski type coil. 
     Such a sensor is only sensitive to conducted noise. 
     Generally, the conducted noise source includes an energy or direct-direct converter comprising switching components generating a signal with harmonics over a relatively broad frequency band. The radiated noise is also generated by the converter. The radiated noise is emitted by the conductors of the signal emitted by the converter. Upon passage of the signal emitted by the converter, these conductors form an antenna emitting the initial radiated noise. 
     The converter generates a signal ranging from direct current up to the frequency band corresponding to the AM band (amplitude modulation), and even beyond that. The low-frequency components, referred to as energy frequencies, of the noise have a very high power. These energy frequencies completely mask the noise in the AM band where the noise power is relatively weak. However, the noise power in the AM band is sufficiently strong to corrupt the vehicle reception antenna. It is therefore preferable to get a good measurement of the noise in the frequency band of the signal of interest to be noise corrected, meaning in the frequency band above the energetic frequencies. Such a coil acts as a high pass filter with a cutoff frequency which is relatively low and below 500 kHz. Thus, the sensor only measures the frequencies included in a set frequency range and higher than the energetic frequencies which are not of interest. 
     Furthermore, such a coil is linear in the amplitude modulation (AM) radio reception band and is not saturated by the current that it measures despite the high value that this current could have. 
     Additionally, such a coil is sensitive to low amplitude signals, and therefore to the noise. 
     Further, since an automobile includes many electronic components using high currents, a sensor containing a ferromagnetic material would saturate and would have a nonlinear behaviour with hysteresis. 
     A Rogowski type coil does not have these disadvantages because it only includes a toroid containing a dielectric material, or an air toroid. 
     Advantageously, the means for estimating the modified radiated noise from the conducted noise include an adaptive filter. 
     Such a filter for example is the Wiener type filter and is particularly suited for noise correction, especially when the signals and the noise are quasi-stationary, or even stationary or slowly varying. 
     According to another optional feature of the device, it includes means for conversion of the noisy signal of interest and/or conducted noise measured in an analogue mode into a digital mode, where the means of conversion are arranged upstream of the means for determining the noise corrected signal of interest. 
     The change from analogue to digital mode and also the use of a sub-sampling technique makes it possible to reduce the quantity of data to be handled, and the time for processing the noisy signal of interest by the determination means. 
     According to other optional features of the device: 
     the device includes means for selecting a receiving frequency for radiofrequency signals. These means of selection comprise in particular a radio tuner. They enable the frequency of the desired radio station to be selected. 
     The device includes means for mixing the noisy signal of interest and/or the measured conducted noise and/or the noise corrected signal of interest with a conversion signal having a conversion frequency, into a noisy intermediate signal of interest and/or a measured conducted intermediate noise and/or a noise corrected intermediate signal of interest having a single intermediate frequency. In the case where the signal is converted to digital mode, the noisy intermediate signal of interest can be obtained by simple multiplication. This in particular avoids the use of nonlinear analogue components. 
     Another advantage is the improvement of the frequency selectivity of the filtering. Actually, since the bandwidth increases with the frequency, it is easier to filter and obtain good selectivity by using the noisy intermediate signal of interest which has a frequency below the frequency or frequencies of the noisy signal of interest. 
     Means for mixing and means for selection are shared. 
     In the case where the device for receiving the noisy signal of interest is a radio tuner, the various frequencies such as those of different radio stations are converted into a single intermediate frequency. Therefore, the various stations can always be received by simply adjusting the conversion frequency. 
     In this case, the means of mixing provide the radio tuner function. 
     Advantageously, the means of selection and/or the means of mixing are arranged downstream of the determination means for the noise corrected signal of interest. Thus the noise correction is performed before the receiving frequency for the radiofrequency signal or the conversion frequency is selected, especially when a very high radiated noise level is involved. 
     The object of the invention is also an electromagnetic noise reduction process in a hybrid automotive vehicle, in which:
         at least one conducted noise generated by at least one noise source is measured;   a radiated noise, referred to as modified, on a signal of interest made noisy by the modified radiated signal, is estimated from the conducted noise, where the modified radiated noise is obtained from the radiated noise, referred to as initial, generated by the noise source and modified by the device environment, and   the noise corrected signal of interest is determined from the noisy signal of interest and the estimate of the modified radiated noise.       

     Another object of the invention is an assembly comprising:
         at least one noise source with an energy converter and a DC-DC converter;   at least one noise reduction device as defined above including at least one conducted noise sensor between the energy converter and the DC-DC converter and at least one conducted noise sensor between the energy converter and an electric motor.       

     The object of the invention is also a vehicle comprising a noise reduction device as defined above or an assembly as defined above. 
     The invention will be better understood by reading the following description, given solely as a non limiting example and referring to the following drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows schematically various functional units of a vehicle including a noise reduction device in accordance with the invention. 
         FIG. 2  shows variations of the spectral energy density of a noisy signal of interest as a function of frequency. 
         FIG. 3  shows schematically the noise reduction device from  FIG. 1  in accordance with a first embodiment. 
         FIG. 4  shows schematically a part of the noise reduction device from  FIG. 3 . 
         FIG. 5  shows a connection between a DC-DC converter and an energy converter. 
         FIG. 6A  shows a variant of a connection between an electric motor and an energy converter. 
         FIG. 6B  shows a variant of a connection between an electric motor and an energy converter. 
         FIG. 7  shows a sensor for the noise reduction device from  FIG. 1 . 
         FIG. 8  shows a sensor for the noise reduction device from  FIG. 1 . 
         FIG. 9  shows a sensor for the noise reduction device from  FIG. 1 . 
         FIG. 10  shows the transfer function curve of the sensors from  FIGS. 5 to 9  on which gain variations due to frequency are shown for frequency values ranging from 150 kHz to 20 MHz. 
         FIG. 11  shows the transfer function curve of the sensors from  FIGS. 5 to 9  on which gain variations due to frequency are shown for frequency values ranging from 150 kHz to 20 MHz. 
         FIG. 12  shows the transfer function curve of the sensors from  FIGS. 5 to 9  on which gain variations due to frequency are shown for frequency values ranging from 150 kHz to 20 MHz. 
         FIG. 13  shows schematically a noise reduction device in accordance with a second embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  shows a drawing of an electric installation  10  within a vehicle  12 . The vehicle  12  is a hybrid. 
     The vehicle  12  includes an electric energy source  14  with a battery  16 . The vehicle  12  also includes two noise sources comprising respectively a DC-DC voltage converter  18  and an energy converter  20 . Each source  18 ,  20  generates noise which is electromagnetically conducted and radiated. The vehicle  12  also includes at least one device  22  that includes in particular an electric portion  24  of the vehicle motor which furthermore comprises a combustion portion (not shown). Reference signals S 1,A  and S 1,B  travel respectively between both the source  20  and the device  22  and also the source  20  and the source  18 . 
     The sources  18  and  20  generate both a conducted noise, respectively B C,A,  B C,B , transmitted by the means  26  and also initial noises, referred to as radiated, respectively B ii,A , B ii,B , emitted by the means  26  as electromagnetic waves. The initial radiated noises are modified by the installation environment  10 , here the frame of the vehicle  12 . Thus, the modified radiated noises B im,A , B im,B  are obtained respectively from the modified radiated noises B ii,A  and B ii,B . 
     The noise sources  18 ,  20  and the device  22  are connected to each other by the means  26  for wired transmission of the signals S 1,A , S 1,B  which conduct respectively conducted noises B C,A , B C,B  and which flow respectively from source  18  to source  20  and from source  20  to the device  22 . 
     The vehicle  12  also includes a device  28  for receiving electromagnetic waves including an antenna  30 , a tuner  32  for amplitude modulation (AM) waves in a frequency band ranging from 535 kHz to 1605 kHz and a unit  33  for reduction of the modified radiated noise B im,A , B im,B  on a noisy signal of interest S 2  flowing from antenna  30  to tuner  32  and unit  33 . 
     The antenna  30  is connected to the tuner  32  and the noise reduction unit  33  by the means  40  of wired transmission of the noisy signal of interest S 2 . 
     The installation  10  also includes two sensors  44 A,  44 B respectively for the conducted noises B C,A , B C,B  generated by the sources  18 ,  20  respectively on the reference signals S 1,A , S 1,B . 
       FIG. 2  shows a spectral energy density of the noisy signal of interest S 2 . The spectral energy density represents the energy variation as a function of the frequency. Two frequency bands B 1 , B 2  are distinguished. Band B 1  corresponds to frequencies substantially ranging from 0 to 500 kHz and band B 2  corresponds to frequencies substantially ranging from 500 kHz to 2 MHz. Band B 2  corresponds to the amplitude modulation (AM) radio receiving frequency band.  FIG. 2  illustrates the variations of the noisy signal of interest S 2  including the noisy signal of interest S 3  and the modified radiated noises B im,A , B im,B  which are represented by amplitude artefacts which are relatively small compared to the amplitude of the signal S 2  or S 3 . In other terms, S 2 =S 3 +B im,A +B im,B =S 3 +B im  where B im  is a function of the modified radiated noises B im,A , B im,B  and therefore represents all the modified radiated noises. A total measured conducted noise B C  is also defined which is a function of B C,A , B C,B  and which therefore represents all the conducted noises. 
     Referring to  FIG. 3 , the unit  33  includes a bandpass filter  46  and also the means  48  of conversion (ADC) of the conducted noise B C  and the noisy signal of interest S 2  from analogue to digital. The means  48  of conversion have a sampling frequency F e  substantially equal to twice a maximum frequency F i  of the radiated noise from sources  18 ,  20 . In the case at hand, Fe=10 MHz where F i &lt;5 MHz. 
     The unit  33  also includes the means  50  for reducing the sampling rate, and a bandpass filter  52  placed downstream of the means  50 . Furthermore, the unit  33  includes the means  53  for noise correction of the noisy signal of interest S 2 . The unit  33  includes the means  54  of frequency processing of the noise corrected signal of interest S 3 , the means  56  for conversion (DAC) of the noise corrected signal of interest S 3  from digital to analogue, and means  58  for demodulation of the noise corrected signal of interest S 3 . The means  48  of conversion are positioned upstream of the means  53 . 
     The means  54  of frequency processing are arranged downstream of the means  53  for determining the noise corrected signal of interest S 3 . 
     Referring to  FIG. 4 , the means  53  include the means  60  for determining the noise corrected signal of interest S 3  from the noisy signal of interest S 2  and the conducted noise B C . The means  53  also include the means  62 ,  64  of frequency processing of the signals arranged respectively upstream and downstream of the means  60 . 
     The means  62  comprise two Fast Fourier Transform units for the noisy signal of interest S 2  and the conducted noises B C,A , B C,B  forming a total conducted noise B C  into respectively signals S 2 ′ and B C ′. The means  64  include an inverse fast Fourier transform unit for the transformed noise corrected signal S 3 ′ into the noise cancel signal S 3 . 
     The means  60  include means  66  for estimation of the total modified radiated noise B im , meaning the modified radiated noises B im,A , B im,B  from the total conducted noise B C , meaning the conducted noises B C,A , B C,B . The means  60  also include means  68  for subtraction of the estimated modified radiated noise B ime , meaning the modified radiated noise B ime,A , B ime,B  estimated by the means  66 , from the noisy signal of interest S 2 . Thus, means  60  perform the following operation: S 3 ′(t)=S 2 ′−B ime +f(S 3 ′(t−1))=S 2 ′−(B ime,A +B ime,B )+f(S 3 ′(t−1)). In this case, means  66  include a Wiener type adaptive filter with multiple noise reference. 
     The means  54  for frequency processing include means  70  for mixing the noise corrected signal of interest S 3  with a conversion signal S 4  having a single conversion frequency F 4  into a noise corrected intermediate signal of interest S 5  with single intermediate frequency F 5 . In this case, the means  70  comprise an IF (Intermediate Frequency) type converter. The means  70  form the means for selection of frequency F 5  for receiving a radiofrequency signal by the receiving device  32  from the noisy signal of interest S 2 . The means for selection and the means for mixing are shared. As a variant, they are distinct. 
     The vehicle  12  therefore includes a noise reduction device including the sensors  44 A,  44 B and the unit  33  including the means  60  including means  66 . This device enables the reduction in radiated electromagnetic noise according to the following sequence of steps:
         The sources  18 ,  20  generate the conducted noises B C,A , B C,B  and the initial radiated noises B ii,A , B ii,B .   The noises B ii,A , B ii,B  are modified by the environment of the vehicle into respectively B im,A , B im,B  modified radiated noises.   The conducted noises B C,A , B C,B  and the signal of interest S 2  are all measured. The number of noises B C  depends on the number of sources of noise in the vehicle.       

     Thus, one conducted noise sensor corresponds to each source.
         The conducted noises B C,A , B C,B  and the signal of interest S 2  are all three processed successively by filters  46 , means  40 ,  50  and filters  52 .   The modified radiated noises B im,A , B im,B  are then estimated by means  66 .   The noise corrected signal S 3  is determined by means  68 .   The frequency F 5  of the noise corrected signal S 3  is selected using shared means  54 ,  70 .   The noise corrected signal S 3  is finally processed by means  56  and  58 .       

     Each sensor  44 A,  44 B is solely sensitive to conducted noises B C,A , B C,B  and is insensitive to the radiated electromagnetic signals. As shown in  FIG. 5 , sensor  44 A is arranged around a conducting wire of the means of transmission by wire  26  between the battery  16  and converter  18  on one side and the converter  20  on the other side. 
       FIG. 6A  shows a single sensor  44 B. The sensor  44 B is arranged around all the conductor phase wires  26 B 1-3  between converter  20  and device  22 . The conducted noise B C,A  is therefore measured simply by means of a single sensor, which is economical. 
     In  FIG. 6B  a variant is shown in which the sensor  44 B includes three sensors  44 B 1 ,  44 B 2  and  44 B 3 . The sensors  44 B 1-3  are identical to each other and each one is arranged around respectively one conductor phase wire  26 B 1-3  of the means  26  between the converter  20  and the device  22 . Thus, each noise is measured independently. Also a subsequent processing step is done comprising an adaptive filtering using the measured noises. 
     Referring to  FIGS. 7 ,  8  and  9 , each sensor  44  includes a Rogowski type coil  72 . The coil  72  has a general toroidal shape around an axis Z and includes a hollow toroidal support  75  of dielectric material covered with a protective coating  76  of heat shrink plastic. The coil  72  includes two ends  78 ,  80  and also a sleeve  82  for connecting of the two ends  78 ,  80 . The coil  72  also includes an insulated electric cable  84  passing inside the toroidal support  74  and wound around the toroidal support. The support  74  of the sensor  44  has external diameter D e  and internal diameter D i  substantially equal respectively to 52 mm and 36 mm. The cross section shows an external diameter Ds of about 8 mm. Each sensor  44  also includes the means  86  for integration of the variations of the signal measured by the coil  72 . These means  86  of integration include a capacitor  88  and resistor  90  shown in  FIG. 7 . 
     Other features of the coil  72  for the sensor  44 A are described in Table 1 below with reference to  FIG. 10  in which variations of the gain based on frequency, are shown for frequency values ranging from 150 kHz to 20 MHz. 
     
       
         
               
               
               
             
               
               
               
               
             
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Property 
                 Value 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Sensitivity at 1 MHz 
                 0.55  
                 V/A 
               
               
                   
                 Bandwidth R = 20 Ω, C = 22 nF 
                 10.85  
                 MHz 
               
               
                   
                 Central frequency F 0   
                 2.24  
                 MHz 
               
             
          
           
               
                   
                 Cutoff frequencies F 1 , F 2   
                 445 kHz and 11.29 MHz 
               
             
          
           
               
                   
                 Frequency F 3  of maximum gain 
                 844  
                 kHz 
               
               
                   
                 Minimum loss in frequency F 3   
                 33.5  
                 dB 
               
               
                   
                 Input impedance at 1 MHz 
                 13.2  
                 Ω 
               
               
                   
                 Inductance at 1 MHz 
                 1.42  
                 μH 
               
               
                   
                   
               
             
          
         
       
     
     The external diameter D e  and internal diameter D i  of the toroidal support  74  for the sensors  44 B 1-3  are substantially equal to 45 mm and 29 mm respectively. Other features of the coil  72  for the sensors  44 B 1-3  are described in Table 2 below with reference to  FIG. 11 . 
     
       
         
               
               
               
             
               
               
               
               
             
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Property 
                 Value 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Sensitivity at 1 MHz 
                 0.5  
                 V/A 
               
               
                   
                 Bandwidth R = 20 Ω, C = 22 nF 
                 12.1  
                 MHz 
               
               
                   
                 Central frequency F 0   
                 2.5  
                 MHz 
               
             
          
           
               
                   
                 Cutoff frequencies F 1 , F 2   
                 499 kHz and 12.6 MHz 
               
             
          
           
               
                   
                 Frequency F 3  of maximum gain 
                 1.08  
                 MHz 
               
               
                   
                 Minimum loss in frequency F 3   
                 32.7  
                 dB 
               
               
                   
                 Input impedance at 1 MHz 
                 15.4  
                 Ω 
               
               
                   
                 Inductance at 1 MHz 
                 2.05 
                 μH 
               
               
                   
                   
               
             
          
         
       
     
     The external diameter De and internal diameter Di of the toroidal support  74  for the sensor  44 B 4  are substantially equal to 70 mm and 54 mm respectively. Other features of the coil according to the first embodiment are described in Table 3 below with reference to  FIG. 12 . 
     
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Property 
                 Value 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Sensitivity at 1 MHz 
                 0.4  
                 V/A 
               
               
                   
                 Frequency F 3  of maximum gain 
                 600  
                 kHz 
               
               
                   
                 Minimum loss in frequency F 3   
                 35.5  
                 dB 
               
               
                   
                 Input impedance at 1 MHz 
                 15.8 
                 Ω 
               
               
                   
                 Inductance at 1 MHz 
                 1.3 
                 μH 
               
               
                   
                   
               
             
          
         
       
     
       FIG. 13  shows an installation according to a second embodiment. Elements similar to those shown in the previous Figs. are designated using the same references. 
     In this embodiment, the means  54  for frequency processing are placed between means the  48  and means  50 . Furthermore, the frequency processing means  54  include means  70  for mixing the noisy reference signal S 2  with the conversion signal and the conducted noise B C  with a different conversion signal. The means  70  for mixing are connected to each other such that the intermediate frequencies of the signals coming from means  70  are compatible, actually identical. 
     The invention is not limited to the previously described embodiments. 
     The device could comprise a single conducted noise sensor used for noise correction of the received radio signal in the car. 
     Having described and illustrated the principles of this application by reference to one or more preferred embodiments, it should be apparent that the preferred embodiments may be modified in arrangement and detail without departing from the principles disclosed herein and that it is intended that the application be construed as including all such modifications and variations insofar as they come within the spirit and scope of the subject matter disclosed herein. 
     This application claims the benefit of French Patent Application FR 0958492 filed Nov. 30, 2009, the entire disclosure of which is incorporated by reference herein. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 [Reference Signs List] 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10 
                 Installation environment 
               
               
                   
                 12 
                 Vehicle 
               
               
                   
                 14 
                 Electric energy source 
               
               
                   
                 16 
                 Battery 
               
               
                   
                 18 
                 Source 
               
               
                   
                 20 
                 Energy converter 
               
               
                   
                 22 
                 Device 
               
               
                   
                 24 
                 Electric portion 
               
               
                   
                 26 
                 Mean 
               
               
                   
                 26B 1 , 26B 2 , 26B 3   
                 Conductor phase wire 
               
               
                   
                 28 
                 Device 
               
               
                   
                 30 
                 Antenna 
               
               
                   
                 32 
                 Tuner 
               
               
                   
                 33 
                 Unit 
               
               
                   
                 40 
                 Mean 
               
               
                   
                 44, 44A, 44B, 44B 1 , 44B 2 , 44B 3 , 44B 4   
                 Sensor 
               
               
                   
                 46 
                 Filter 
               
               
                   
                 48 
                 Mean 
               
               
                   
                 50 
                 Mean 
               
               
                   
                 52 
                 Filter 
               
               
                   
                 53 
                 Mean 
               
               
                   
                 54 
                 Mean 
               
               
                   
                 56 
                 Mean 
               
               
                   
                 58 
                 Mean 
               
               
                   
                 60 
                 Mean 
               
               
                   
                 62 
                 Mean 
               
               
                   
                 64 
                 Mean 
               
               
                   
                 66 
                 Mean 
               
               
                   
                 68 
                 Mean 
               
               
                   
                 70 
                 Mean 
               
               
                   
                 72 
                 Coil 
               
               
                   
                 74 
                 Support 
               
               
                   
                 76 
                 Protective coating 
               
               
                   
                 78 
                 End 
               
               
                   
                 80 
                 End 
               
               
                   
                 82 
                 Sleeve 
               
               
                   
                 84 
                 Insulated electric cable 
               
               
                   
                 86 
                 Mean 
               
               
                   
                 88 
                 Capacitor 
               
               
                   
                 90 
                 Resistor