Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
120 words
A circuit for monitoring a sensor located in a hazardous region comprising: conductors extending from the sensor to a nonhazardous region; a source of line voltage in the nonhazardous region; a first voltage stepdown transformer having its primary connected to the voltage source; indicating means responsive to the Sensor and located in the nonhazardous region, a second voltage stepdown transformer having its primary connected to said indicating means; the secondaries of said first and second transformers being connected in series with each other and in series with the sensor through said conductors; whereby faults arising in either the indicating means, the transformer primaries, or in the sensor or its conductors, present a substantially reduced energy discharge in the hazardous region.
Claim 2
Dependent Claim
120 words
A circuit for monitoring a sensor located in a hazardous region comprising: conductors extending from the sensor to a nonhazardous region; a source of line voltage in the nonhazardous region; a first voltage stepdown transformer having its primary connected to the voltage source; indicating means responsive to the Sensor and located in the nonhazardous region, a second voltage stepdown transformer having its primary connected to said indicating means; the secondaries of said first and second transformers being connected in series with each other and in series with the sensor through said conductors; whereby faults arising in either the indicating means, the transformer primaries, or in the sensor or its conductors, present a substantially reduced energy discharge in the hazardous region.
Claim 3
Dependent Claim
40 words
A circuit according to claim 1 wherein in each stepdown transformer the primary winding is separated from the secondary winding by a sheet of material acting as a barrier to prevent the primary voltage from appearing across the secondary winding.
Claim 4
Dependent Claim
17 words
A circuit according to claim 2 wherein said barrier sheet is conductive and is connected to ground.
Claim 5
Dependent Claim
18 words
A circuit according to claim 1 wherein each of said transformers comprises a conductive core connected to ground.
Claim 6
Dependent Claim
24 words
A circuit according to claim 1 wherein said indicating means comprises a relay having its winding connected in series with said second transformer primary.
Claim 7
Dependent Claim
22 words
A circuit according to claim 1 wherein said sensor comprises a switch adapted to be opened and closed in said hazardous region.
Claim 8
Dependent Claim
25 words
A circuit according to claim 1 further comprising current-limiting resistances located in said nonhazardous area and connected in series with each of said transformer secondaries.
Claim 9
Dependent Claim
133 words
A circuit for monitoring the condition of a sensor located in a hazardous region by means of an indicator responsive to the sensor, comprising: a first isolation module having input terminals for connection to a source of voltage, and output terminals; a second isolation module having input terminals for connection to said indicator, and output terminals; said first and second isolation modules being located in a nonhazardous region; and conductors extending from said sensor to said nonhazardous region and being connected to said isolation module output terminals; each of said isolation modules comprising a voltage stepdown transformer having its primary across the module input terminal; the secondary of said transformer being connected in series between current-limiting resistances to the module output terminals; said transformer and said current-limiting resistances being embedded in potting material.
Claim 10
Dependent Claim
133 words
A circuit for monitoring the condition of a sensor located in a hazardous region by means of an indicator responsive to the sensor, comprising: a first isolation module having input terminals for connection to a source of voltage, and output terminals; a second isolation module having input terminals for connection to said indicator, and output terminals; said first and second isolation modules being located in a nonhazardous region; and conductors extending from said sensor to said nonhazardous region and being connected to said isolation module output terminals; each of said isolation modules comprising a voltage stepdown transformer having its primary across the module input terminal; the secondary of said transformer being connected in series between current-limiting resistances to the module output terminals; said transformer and said current-limiting resistances being embedded in potting material.
Claim 11
Dependent Claim
37 words
A circuit according to claim 8 wherein each of said isolation modules comprises a conductive sheet separating its secondary and primary windings, said sheet being grounded, and wherein each of said transformers comprises a grounded conductive core.