US3777265A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Induction ammeter with self induced restoring torque
Assignee: ELECTRO MECHANICAL INSTR DIV V
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Filing: 1973-01-19
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Granted: 1973-12-04
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Expires: 1993-01-19
Abstract
Abstract In a moving magnet meter a dial blank of soft magnetic material has tabs which are aligned with the poles of the moving magnet to establish the zero setting of the pointer. The pointer is rotationally deflected over the dial by the magnetic field which is established transverse to the line of the tabs by current flowing through a conductor carrying current to be measured. With no current in the conductor the magnetic axis of the magnet aligns itself with the induced pole arms in the tabs as a path of minimum reluctance. The tabs can be easily adjusted to control the sensitivity of the meter and the magnitude of the restoring torque.
Inventors
- 👤 L Void
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:35
CPC Classifications
G; G01; G01R; G01R5/00; G01R5/14; G01R5/16
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
129 words
An electric meter comprising: a rotatably mounted arbor, a permanent magnet mounted on said arbor, indicating means mounted on said arbor, a dial blank of soft magnetic material positioned in relation to said indicator so that rotation of said indicator registers the magnitude of an electrical quantity with respect to indicia on said dial blank, tabs extending from said dial blank into proximity with the two poles of said permanent magnet so that the two poles of said permanent magnet are aligned with said two tabs at the unenergized setting of said indicator with respect to said indicia, and means for establishing a magnetic field approximately transverse to the line of said tabs to rotationally deflect the magnet as a measure of the electrical quantity inducing the magnetic field.
Claim 2
Dependent Claim
129 words
An electric meter comprising: a rotatably mounted arbor, a permanent magnet mounted on said arbor, indicating means mounted on said arbor, a dial blank of soft magnetic material positioned in relation to said indicator so that rotation of said indicator registers the magnitude of an electrical quantity with respect to indicia on said dial blank, tabs extending from said dial blank into proximity with the two poles of said permanent magnet so that the two poles of said permanent magnet are aligned with said two tabs at the unenergized setting of said indicator with respect to said indicia, and means for establishing a magnetic field approximately transverse to the line of said tabs to rotationally deflect the magnet as a measure of the electrical quantity inducing the magnetic field.
Claim 3
Dependent Claim
81 words
The electric meter recited in claim 1 wherein said meter is an induction ammeter and wherein a conductor carrying current to be measured is coupled in a line which is substantially parallel to the line of said tabs to establish said magnetic field having a magntidue related to the current through said conductor and whereby the magnetic axis of said permanent magnet aligns itself with said tabs as a path of minimum reluctance when there is no current in said cable.
Claim 4
Dependent Claim
56 words
The meter recited in claim 2 further comprising: an interrupted channel on the back of said meter, projection on the back of said meter to form a serpentine opening in said channel so that said conductor can be inserted in said opening to secure the conductor to the meter without threading the conductor through the hook.
Claim 5
Dependent Claim
44 words
The meter recited in claim 1 wherein said tabs are adjustable with respect to said permanent magnet to control the restoring torque applied to said permanent magnet, to control the sensitivity of said meter, and to control the unenergized position of said indicating means.
Claim 6
Dependent Claim
52 words
The meter recited in claim 1 further comprising: a molded resilient plastic case for said meter having a flange thereon for engagement with one side of a mounting panel, and a canted screw hole positioned in said case so that a mounting screw can engage the other side of said mounting panel.
Claim 7
Dependent Claim
29 words
The meter recited in claim 5 wherein said canted screw hole is formed by two cores of a die, said cores meeting at a right angle in said case.
Claim 8
Dependent Claim
31 words
The meter recited in claim 5 further comprising: a clear plastic bezel, said plastic case having a groove around the periphery thereof, said clear platic bezel being snapped into said groove.
Claim 9
Dependent Claim
26 words
The meter recited in claim 7 wherein said clear plastic bezel has a serrated and frosted area at one side thereof to hide the meter movement.
References Cited (Backward Citations)
US1463597A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-03 | 1977-06-04 | 1977-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-03 | 1981-06-04 | 1981-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-03 | 1985-06-04 | 1985-12-04 | $7700.00 | Window Closed / Lapsed |