Eaton Corporation

Dennis M Kramer

Richard F Schmerda

Michael A Damiano

Dale Louis Gass

Ralph F Bielinski

M Frank Chacon

Stanley Schneider

William R Mathias

A power controller with overload protection having an alternating current source (AC) connected through power lines (L1, L2) and a pair of power switching devices (FET1, FET2) and a current sensor resistance shunt (SH) in series to a load (LD). A line-derived control power supply circuit (LDS) is connected through one of the power switching devices (FET1) to the lower line (L1, L2) such that the control power supply current does not flow through the shunt (SH) or the load (LD). Close and open commands are applied from a control switch (CSW) through a threshold detector (DT) and a logic circuit (LG1) to operate a latch (LCH) that turns the power switching devices (FET1, FET2) on and off under the clocking control of a zero voltage detector (ZVD) and a zero current detector (ZCD) and the gating control of a minimum current circuit (MCC). An overload circuit (AVC, ITC, TTC) provides instantaneous trip of the latch on rupture current or timed trip of the latch on smaller overloads. Opto-isolated indicators (SS, ST) indicate trip conditions and loss of line voltage conditions as well as whether the load current is above or below a minimum current value which is a current level adequate for operation of the control system.

Solid state power controller with overload protection

A solid state DC power control system having a single N-type or N-channel or majority carrier solid state switching element (Q1) connected to the high side (L) of the power supply for energizing a ground or neutral (V.sub.o) connected load (LD). A voltage level translation circuit (2,2') supplies a floating regulated control voltage to the switching element (Q1) high enough to maintain it turned on even if the voltage at the low side of the switching element (Q1) rises up to or near the supply voltage thereby allowing use of such N-type switching device (Q1) in the high side (L) of the supply. A zener diode (ZD3) limits the gate(G)-to-source(S) voltage to the proper level. A non-inverting drive circuit (10,12) controlled by a logic level signal input element (Q2) controls connection of the high voltage to the switching (Q1) gate (G). A first version uses a DC-DC converter (CON) and a preferred version uses a voltage multiplier (VM) in the voltage level translation, high voltage, gate supply circuit (2,2').

Solid state DC power control system

A resistance wire sensing overcurrent protection module (CSM) for an electrical supply circuit (SC) having a hot temperature sensing diode (32) mounted at the center portion (8c) of an M-shaped resistance wire (8) connected in the supply circuit and an ambient temperature sensing diode (20) mounted on a substrate (18) supported between the supply terminals (4a-b, 6a-b), both diodes being connected to respective pairs of terminals (12a-b, 10a-b) mounted on a header (18) along with the supply terminals. A cover (46) is mounted on the header and filled with glass micro-balloons (48) to isolate thermally the two diodes. A constant current circuit (49) supplies constant current to the two diodes which operate a differential amplifier (52) having an output proportional to the temperature difference as a measure of supply current. This output trips a Schmitt trigger comparator (54) when the supply current rises to an overload value.

Electrothermal wire responsive miniature precision current sensor

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Brookfield, WI, United States of America

Dennis M Kramer