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US 5,198,956 AGranted
Overtemperature sensing and signaling circuit
AssigneeSquare D Company
InventorRobert F. Dvorak
Life of this patent
Estimating the term…
Abstract
An overtemperature sensing and signaling circuit for electronic trip units includes a voltage divider (16) and a trigger circuit (18). The voltage divider is formed of a first resistor (R1) and a positive coefficient resistor (PT1). The trigger circuit is formed of a first bipolar transistor (Q1) of the PNP-type conductivity and a second bipolar transistor (Q2) of the NPN-type conductivity.
Claims14
An overtemperature sensing and signaling circuit for electronic trip units comprising:
- a voltage divider (16) formed of a first resistor (R1) and positive coefficient resistance means (PT1) for sensing the ambient temperature within a circuit interrupter housing, said positive coefficient resistance means being connected between a first node (C) and a ground potential (GND), said first resistor (R1) having its one end connected to a first power supply potential (V.sub.a) and its other end connected to said first node (C);
- a trigger circuit (18) formed of a first switching transistor (Q1) and a second switching transistor (Q2);
- said first switching transistor having its emitter connected to said first node (C);
- and
- said second switching transistor (Q2) having its base connected to the collector of said first switching transistor (Q1), its collector connected to the base of said first switching transistor (Q1) and to a second power supply potential (.sub.cc), and its emitter coupled to a second node (B).
2 more elements
An overtemperature sensing and signaling circuit for electronic trip units comprising:
- thermal-responsive means (PT1) for sensing the ambient temperature within a circuit interrupter housing;
- a trigger circuit (18) formed of a first switching transistor (Q1) and a second switching transistor (Q2);
- said first switching transistor having its emitter connected to said first node (C);
- and
- said second switching transistor (Q2) having its base connected to the collector of said first switching transistor (Q1), its collector connected to the base of said first switching transistor (Q1) and to a second power supply potential (V.sub.cc), and its emitter coupled to a second node (B).
2 more elements
Dependencies are inferred from the claim text.