CA1047137A - Externally ventilated strip-resistance unit having a high load-carrying capacity - Google Patents
Externally ventilated strip-resistance unit having a high load-carrying capacityInfo
- Publication number
- CA1047137A CA1047137A CA237,783A CA237783A CA1047137A CA 1047137 A CA1047137 A CA 1047137A CA 237783 A CA237783 A CA 237783A CA 1047137 A CA1047137 A CA 1047137A
- Authority
- CA
- Canada
- Prior art keywords
- resistance
- copper
- frame
- connecting bolts
- welded
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910052802 copper Inorganic materials 0.000 claims abstract description 16
- 239000010949 copper Substances 0.000 claims abstract description 16
- 238000001816 cooling Methods 0.000 claims description 5
- 229910000881 Cu alloy Inorganic materials 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 230000000284 resting effect Effects 0.000 claims description 3
- 229910000990 Ni alloy Inorganic materials 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 6
- 230000007797 corrosion Effects 0.000 abstract description 2
- 238000005260 corrosion Methods 0.000 abstract description 2
- 210000003739 neck Anatomy 0.000 abstract 1
- 238000005266 casting Methods 0.000 description 8
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 230000006735 deficit Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 230000005923 long-lasting effect Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C3/00—Non-adjustable metal resistors made of wire or ribbon, e.g. coiled, woven or formed as grids
- H01C3/10—Non-adjustable metal resistors made of wire or ribbon, e.g. coiled, woven or formed as grids the resistive element having zig-zag or sinusoidal configuration
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C1/00—Details
- H01C1/01—Mounting; Supporting
- H01C1/014—Mounting; Supporting the resistor being suspended between and being supported by two supporting sections
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C1/00—Details
- H01C1/08—Cooling, heating or ventilating arrangements
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Connection Of Plates (AREA)
- Connections Effected By Soldering, Adhesion, Or Permanent Deformation (AREA)
- Current-Collector Devices For Electrically Propelled Vehicles (AREA)
- Insertion, Bundling And Securing Of Wires For Electric Apparatuses (AREA)
Abstract
Abstract Disclosed is an externally-ventilated, high-load-carrying-capacity strip resistance unit which consists of a copper-free, meander-pattern resistance strip, the deflecting locations on one end of which are held resiliently to a frame. The deflecting locations on the other end consist of welded-on, copper-containing, U-shaped brackets to which connecting bolts, made of a material containing a larger proportion of copper, are welded. The graduated amounts of copper in the brackets and connecting bolts prevents intercrystalline corrosion of the copper-free resistance strips. Each connecting bolt has a square section which fits into a square recess in an insulating cup, the square outside contour of which projects through a corresponding square aperture in the frame to which it is secured by means of screws, so that the deflecting locations, together with the connecting bolts, are held rigidly and secure against rotation in the frame. Thus when the connecting cables are tightened to the necks of the connecting bolts, there is no turning of the deflection locations and no contact between adjacent welded-on resistance strips.
Description
47~3~7 This invention relates to an externally ventilated strip-resistance unit having a high load-carrying capacity, arLd with resistance paths arranged in a meander pattern and held to, but insulated from, a frame, the said resistance paths consisting of resistance strips with deflection locations, those on the one side having no electrical connections and being resiliently flexible, while those on the other side are welded to the said resistance strips, contain copper, and are held rigidly, but detachably, to the said frame by means of connecting bolts also used for resistance steps and passing through insulating elements supported on the said frame, so that the entire resistance path lies fully exposed in the flow of cooling air.
In the strip-resist~lce unit disclosed in German Public Inspection Text 1,~65,915, the meander-pattern resistance paths, mounted to allow unimpeded heat expansion, consist of straight-profile resist-ance strips with separate deflection locations, preferably made of copperj welded to the ends thereof. Connecting bolts are connected mechanically and electrically to the easily accessible deflection locations situated on one side, the said bolts forming, in conjurlction with the insulating elements through which they pass, rigid screwable means for retaining the resistance paths to the frame. The de M ection locations free of electrical connections, situated on the other side, are held resiliently to the frame. All of the deflection locations are in the form of complex, copper-containing castings adapted to the profiles of the resistance strips, so that in addition to the expense of the castings themselves, a correspondingnumber of such welded castings is required, regardless of the number of electrical connection locations. Satisfactory, long-lasting welds in copper castings require the use of copper-containing resistance strips, but these have a lower load-carrying capacity than resistance strips .~'P~
7~37 containing no copper.
When the connecting cables are screwed to the connecting bolts, the latter, together with the castings and welded-on resistance strips may be inadvertently rotated, so that impairment o-f the cooling or even contact between adjacent resistance strips is possible.
In the known resistance unit, in order to prevent the castings from rotating, mechanical retention is separate -from electrical connection and is achieved by means of separate bolts passing insulatedly through *he castings, thus adding to the expense of the said castings.
It is the purpose of the invention, in the case of resistance paths havlng a particularly high load-carrying capacity~ to restrict the number of deflection locations to be welded to the resistance strips to the deflection locations provided with connection locations, and to manage with deflection locations which are o-f simple configuration, are easily and permanently weldable, and can be secured to the frame so that they are easily detachable and cannot be turned.
This purpose is achieved, according to the invention, in that the copper-containing deflection loccations welded to the copper-free resistance strips are in the form of U-shaped brackets made of an alloy containing less copper than the connecting bolts each consisting oE a bolt head, a square part, and a threaded bolt neck, and in that the head of each connecting bolt passing through its associated bracket rests upon its transverse part and is welded thereto, is held by its square part, which is located outside the said bracket, secured against rotation in an insulating cup, also secured against rotation, resting upon *he frame, and having a square external contour and a square recess, and rests upon the insulating cup by means of an attachment nut screwed to the neck of the bolt.
The in~ention will now be further described in conjunction with the accompanying drawings, in which:
7~37 Figure 1 is a side elevation of a strip--resistance unit in longitudinal section;
Figure 2 is a cross section of the object in Figure l;
Figures 3 and 4 are details of the unit in plan view and cross section Two substantially indentical meander-pattern resistance paths are arranged, in the direction of flow o th~ cooling air, one behind the other, and spaced from each other, in a rigid square frame 1 consisting of a ~ plurality of straight frame parts la, lb,-~e-j ld welded toge-ther. The meanders of resistance strips 2 of each resistance path are held to, but are insulated from, relevant frame parts la and lb, at upper and lower deflection locations 3 and 4, by retaining means 5,6. Upper deflection locations 3, which have no electrical connections, have apertures through which insulating tensioning bolts 6a are passed from inside to outside, so that appropriately shaped, lower bolt heads 6b lie snugly against resistance strips 2 at the said deflection locations. Bolt sleeve 6c projects through insulating cup 11 which has a square external contour and is seated, secured against rotation, in a corresponding aperture in frame part la, resting thereupon by means of an external shoulder lla. Arranged within insulating cup 11 is an internal projection llb with which an annular, disc-shaped abutment 6g arranged around bolt neck 6c engages. Arranged between abutment 6g and a second abutment 6c is a spring 6f which bears against an abutment 6d located by means of a clamp 6e at the end of the bolt neck, and which presses abutment 6g against the said internal projection llb. Lower deflection locations 4, which have no electrical connections, are also secured to frame part lb in the manner described above.
Certain lower deflection locations are provided with e:Lectrical connection locations 7, and these are also retained by insulating cups 11 described above~ but in this case insulating bolts 6a are replaced by ~0~37 electrically conducting bolts 9 which are held rigidly to insulating cups 11 by means of the attachment nuts 10 for the electrical cables. Under heads 9a, bolts 9 have a square part 9c which holds the bolt securely against rotation in the square recess in insulating cup 11. Square part 9c is followed by threaded bolt nect 9b on which, as already stated, attachment nut 10 is screwed.
Connecting bolts 9 are made of a material having a lower value of electrical resistance-than resistance strip 2 in order to avoid any over-heating of the cables and consequent damage to the insulation thereof. Since a direct welded connection between a predominently copper-containing connect-ing bolt and a resistance strip free of copper can lead to :intercrystalline corrosion, a bracket 8 made of a material different from that of connecting bolts 9 and resistance strip 2 is welded to each deflection location ~
requir~ng a connection, transverse portion 8a of each bracket being welded to bolt head 9a. Bracket 8 contains less copper than the connecting bolts, thus ensuring a satisfactory and lasting joint between the material of the resistance strip and the connecting bolts, the specific resistance of connecting bolt 9 being the lowest, and that of the bracket being lower than that of the resistance strip. For example, the latter may be made of a ~
Ni-Cr alloy, the bracket may be made of a ~0% Cu alloy, and the connecting bolt may be made of a 70% Cu alloy. Connecting locations 7' at the beginning and end of the strip have only half brackets 8' of the type mentioned.
Where use is made of one-piece resistance strips2, only specific resistance stages are possible with meanders of given geometrical dimensions.
The use of brackets 8 makes it possible to use strip material of different resistance value between individual connection locations 7,7', i.e.
between the connecting bolts thereof. For example, sections 2a and 2b may be made of the same strip material but of different cross section, so that ~fD47~!L37 although the meanders are of the same length and the connection locations are fixed, any desired resistance steps are available at the said connection locations, as required for the driving and braking resistances of electrical-ly-driven vehicles. Since the heads of the bolts are flat and are narrower than the internal dimensions of the relevant deflection locations in the meanders and brackets, they do not materially impede the flow of cooling airO
In order to provide easy installation and removal of the resistance units, the frame and resistance-strip design described above constitute an assembly unit which is held in, and insulated from, a structure common to all assembly units. Depending upon the side from which the connection locations are to be accessible, the spring-loaded resilient deflection locations may also be arranged at the bottom instead of at the top as shown, in which case all connection locations will be accessible from the top instead of from the bottom.
In the strip-resist~lce unit disclosed in German Public Inspection Text 1,~65,915, the meander-pattern resistance paths, mounted to allow unimpeded heat expansion, consist of straight-profile resist-ance strips with separate deflection locations, preferably made of copperj welded to the ends thereof. Connecting bolts are connected mechanically and electrically to the easily accessible deflection locations situated on one side, the said bolts forming, in conjurlction with the insulating elements through which they pass, rigid screwable means for retaining the resistance paths to the frame. The de M ection locations free of electrical connections, situated on the other side, are held resiliently to the frame. All of the deflection locations are in the form of complex, copper-containing castings adapted to the profiles of the resistance strips, so that in addition to the expense of the castings themselves, a correspondingnumber of such welded castings is required, regardless of the number of electrical connection locations. Satisfactory, long-lasting welds in copper castings require the use of copper-containing resistance strips, but these have a lower load-carrying capacity than resistance strips .~'P~
7~37 containing no copper.
When the connecting cables are screwed to the connecting bolts, the latter, together with the castings and welded-on resistance strips may be inadvertently rotated, so that impairment o-f the cooling or even contact between adjacent resistance strips is possible.
In the known resistance unit, in order to prevent the castings from rotating, mechanical retention is separate -from electrical connection and is achieved by means of separate bolts passing insulatedly through *he castings, thus adding to the expense of the said castings.
It is the purpose of the invention, in the case of resistance paths havlng a particularly high load-carrying capacity~ to restrict the number of deflection locations to be welded to the resistance strips to the deflection locations provided with connection locations, and to manage with deflection locations which are o-f simple configuration, are easily and permanently weldable, and can be secured to the frame so that they are easily detachable and cannot be turned.
This purpose is achieved, according to the invention, in that the copper-containing deflection loccations welded to the copper-free resistance strips are in the form of U-shaped brackets made of an alloy containing less copper than the connecting bolts each consisting oE a bolt head, a square part, and a threaded bolt neck, and in that the head of each connecting bolt passing through its associated bracket rests upon its transverse part and is welded thereto, is held by its square part, which is located outside the said bracket, secured against rotation in an insulating cup, also secured against rotation, resting upon *he frame, and having a square external contour and a square recess, and rests upon the insulating cup by means of an attachment nut screwed to the neck of the bolt.
The in~ention will now be further described in conjunction with the accompanying drawings, in which:
7~37 Figure 1 is a side elevation of a strip--resistance unit in longitudinal section;
Figure 2 is a cross section of the object in Figure l;
Figures 3 and 4 are details of the unit in plan view and cross section Two substantially indentical meander-pattern resistance paths are arranged, in the direction of flow o th~ cooling air, one behind the other, and spaced from each other, in a rigid square frame 1 consisting of a ~ plurality of straight frame parts la, lb,-~e-j ld welded toge-ther. The meanders of resistance strips 2 of each resistance path are held to, but are insulated from, relevant frame parts la and lb, at upper and lower deflection locations 3 and 4, by retaining means 5,6. Upper deflection locations 3, which have no electrical connections, have apertures through which insulating tensioning bolts 6a are passed from inside to outside, so that appropriately shaped, lower bolt heads 6b lie snugly against resistance strips 2 at the said deflection locations. Bolt sleeve 6c projects through insulating cup 11 which has a square external contour and is seated, secured against rotation, in a corresponding aperture in frame part la, resting thereupon by means of an external shoulder lla. Arranged within insulating cup 11 is an internal projection llb with which an annular, disc-shaped abutment 6g arranged around bolt neck 6c engages. Arranged between abutment 6g and a second abutment 6c is a spring 6f which bears against an abutment 6d located by means of a clamp 6e at the end of the bolt neck, and which presses abutment 6g against the said internal projection llb. Lower deflection locations 4, which have no electrical connections, are also secured to frame part lb in the manner described above.
Certain lower deflection locations are provided with e:Lectrical connection locations 7, and these are also retained by insulating cups 11 described above~ but in this case insulating bolts 6a are replaced by ~0~37 electrically conducting bolts 9 which are held rigidly to insulating cups 11 by means of the attachment nuts 10 for the electrical cables. Under heads 9a, bolts 9 have a square part 9c which holds the bolt securely against rotation in the square recess in insulating cup 11. Square part 9c is followed by threaded bolt nect 9b on which, as already stated, attachment nut 10 is screwed.
Connecting bolts 9 are made of a material having a lower value of electrical resistance-than resistance strip 2 in order to avoid any over-heating of the cables and consequent damage to the insulation thereof. Since a direct welded connection between a predominently copper-containing connect-ing bolt and a resistance strip free of copper can lead to :intercrystalline corrosion, a bracket 8 made of a material different from that of connecting bolts 9 and resistance strip 2 is welded to each deflection location ~
requir~ng a connection, transverse portion 8a of each bracket being welded to bolt head 9a. Bracket 8 contains less copper than the connecting bolts, thus ensuring a satisfactory and lasting joint between the material of the resistance strip and the connecting bolts, the specific resistance of connecting bolt 9 being the lowest, and that of the bracket being lower than that of the resistance strip. For example, the latter may be made of a ~
Ni-Cr alloy, the bracket may be made of a ~0% Cu alloy, and the connecting bolt may be made of a 70% Cu alloy. Connecting locations 7' at the beginning and end of the strip have only half brackets 8' of the type mentioned.
Where use is made of one-piece resistance strips2, only specific resistance stages are possible with meanders of given geometrical dimensions.
The use of brackets 8 makes it possible to use strip material of different resistance value between individual connection locations 7,7', i.e.
between the connecting bolts thereof. For example, sections 2a and 2b may be made of the same strip material but of different cross section, so that ~fD47~!L37 although the meanders are of the same length and the connection locations are fixed, any desired resistance steps are available at the said connection locations, as required for the driving and braking resistances of electrical-ly-driven vehicles. Since the heads of the bolts are flat and are narrower than the internal dimensions of the relevant deflection locations in the meanders and brackets, they do not materially impede the flow of cooling airO
In order to provide easy installation and removal of the resistance units, the frame and resistance-strip design described above constitute an assembly unit which is held in, and insulated from, a structure common to all assembly units. Depending upon the side from which the connection locations are to be accessible, the spring-loaded resilient deflection locations may also be arranged at the bottom instead of at the top as shown, in which case all connection locations will be accessible from the top instead of from the bottom.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An externally ventilated, high-load-carrying-capacity strip-resistance unit having resistance paths arranged in a meander pattern and held to, but insulated from, a frame, the said resistance paths consisting of resistance strips with deflection locations at opposite ends of the frame, those at one end having no electrical connections and being resiliently flexible, while those on the other end are welded to the said resistance strips, contain copper, and are held rigidly, but detachably, to the said frame by means of connecting bolts also used for resistance stages and passing through insulating elements supported on the said frame, so that the entire resistance path lies fully exposed in a flow of cooling air, characterized in that the copper-containing deflection locations welded to the copper-free resistance strips are in the form of U-shaped brackets made of an alloy containing less copper than the connecting bolts each consisting of a bolt head, a square part, and a threaded bolt neck, and in that the head of each connecting bolt, passing through its associated bracket, rests upon the transverse portion of the bracket and is welded thereto, is held by its square part which is located outside the said bracket, secured against rotation in an insulating cup, also secured against rotation, resting upon the frame and having a square external contour and a square recess, and rests upon the insulating cup by means of an attachment nut screwed to the neck of the bolt.
2. A unit according to claim 1, characterized in that the brackets are made of a 40% copper alloy, the connecting bolts of a 70% copper alloy, and the resistance strips of a chrome-nickel alloy.
3. A unit according to claim 1 or 2, characterized in that half-brackets are provided for terminal connection locations and are welded to the resistance strips and to the connecting bolts.
4. A unit according to claim 1, characterized in that sections of the resistance strips having the same length are of different cross section between two adjacent electrical connecting bolts.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19742452496 DE2452496C2 (en) | 1974-11-05 | 1974-11-05 | Heavy-duty, externally ventilated tape resistance device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1047137A true CA1047137A (en) | 1979-01-23 |
Family
ID=5930094
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA237,783A Expired CA1047137A (en) | 1974-11-05 | 1975-10-16 | Externally ventilated strip-resistance unit having a high load-carrying capacity |
Country Status (6)
| Country | Link |
|---|---|
| AT (1) | AT333893B (en) |
| CA (1) | CA1047137A (en) |
| CH (1) | CH594271A5 (en) |
| DE (1) | DE2452496C2 (en) |
| FR (1) | FR2290826A7 (en) |
| NL (1) | NL7510502A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110323017A (en) * | 2019-06-17 | 2019-10-11 | 株洲中车奇宏散热技术有限公司 | A kind of method and resistance unit rotating isolated insulation resistor disc by integral insulation pipe |
| CN110323018A (en) * | 2019-06-17 | 2019-10-11 | 株洲中车奇宏散热技术有限公司 | A kind of resistor using whole porcelain tube isolation resistance element |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3429390A1 (en) * | 1984-08-09 | 1986-02-20 | Siemens AG, 1000 Berlin und 8000 München | Insulating body having a central passage for a supporting rod |
| DE4008422A1 (en) * | 1990-03-16 | 1991-09-19 | Asea Brown Boveri | Electrical power resistor for thyristor - has folded strip resistor elements in housing with circulated cooling fluid |
| DE29506779U1 (en) | 1994-11-30 | 1996-04-04 | Siemens AG, 80333 München | Resistance device |
| DE102023201751A1 (en) * | 2023-02-27 | 2024-08-29 | Robert Bosch Gesellschaft mit beschränkter Haftung | Braking resistance of an electrically powered vehicle |
-
1974
- 1974-11-05 DE DE19742452496 patent/DE2452496C2/en not_active Expired
-
1975
- 1975-09-02 AT AT675675A patent/AT333893B/en not_active IP Right Cessation
- 1975-09-05 NL NL7510502A patent/NL7510502A/en not_active Application Discontinuation
- 1975-10-16 CA CA237,783A patent/CA1047137A/en not_active Expired
- 1975-10-22 CH CH1365275A patent/CH594271A5/xx not_active IP Right Cessation
- 1975-11-04 FR FR7533670A patent/FR2290826A7/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110323017A (en) * | 2019-06-17 | 2019-10-11 | 株洲中车奇宏散热技术有限公司 | A kind of method and resistance unit rotating isolated insulation resistor disc by integral insulation pipe |
| CN110323018A (en) * | 2019-06-17 | 2019-10-11 | 株洲中车奇宏散热技术有限公司 | A kind of resistor using whole porcelain tube isolation resistance element |
| CN110323017B (en) * | 2019-06-17 | 2021-09-24 | 株洲中车奇宏散热技术有限公司 | Method for isolating insulated resistor disc through rotation of integral insulating tube and resistor unit |
| CN110323018B (en) * | 2019-06-17 | 2022-03-29 | 株洲中车奇宏散热技术有限公司 | Resistor for isolating resistance element by using integral ceramic tube |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2452496C2 (en) | 1976-10-14 |
| ATA675675A (en) | 1976-04-15 |
| DE2452496B1 (en) | 1976-02-12 |
| FR2290826A7 (en) | 1976-06-04 |
| AT333893B (en) | 1976-12-10 |
| CH594271A5 (en) | 1977-12-30 |
| NL7510502A (en) | 1976-05-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20060222346A1 (en) | Electric heating device, in particular for a vehicle heating and heating and/or air-conditioning apparatus | |
| CA1047137A (en) | Externally ventilated strip-resistance unit having a high load-carrying capacity | |
| US5411417A (en) | Terminal block arrangement with overvoltage protection component | |
| US3245021A (en) | Shunt for electrical instruments | |
| KR100244927B1 (en) | Resistor device for blower motor | |
| DE4108789A1 (en) | Temp. sensor suitable for air stream of turbo-charger in motor vehicle - uses electronic component whose electrical resistance varies with temp. and fixed to end face of housing | |
| FR2762750A1 (en) | FLAT CONDUCTOR BAR ASSEMBLY FOR A CONVERTER | |
| US4359710A (en) | Annular resistor with zig-zag layer pattern for resistance elements | |
| DE10209905A1 (en) | Electric heater, especially throughflow heater, has switch semiconducting body attached to heat conducting closure part of heating device chamber on side remote from chamber for switch cooling | |
| US2626309A (en) | Heavy-duty meter facilities | |
| EP0748511A1 (en) | Thermistor | |
| US1327844A (en) | Connector-clip | |
| US3614731A (en) | Transport vehicle axle bearing alarm | |
| US1526649A (en) | Resistance device | |
| US2647978A (en) | Resistance unit and element thereof | |
| DE3617611C2 (en) | ||
| JPH11186478A (en) | Semiconductor module | |
| US2863974A (en) | Heat dissipating electrical circuit component | |
| DE19952179A1 (en) | Electrical protection switching device | |
| US2656493A (en) | Metallic rectifier construction | |
| US1031382A (en) | Grid-resistance. | |
| US1249429A (en) | Multiple lightning-arrester. | |
| SE433259B (en) | ASSEMBLY AND VALVE | |
| US2050220A (en) | Terminal for edge wound resistors | |
| SE445504B (en) | RELETUNGENHET |