Dc bus resistive path to ground fault detector

Claim 2

A detector for indicating a resistive path to ground fault on either bus of a pair of ungrounded buses conducting electric power to a load, said detector comprising: a. a gate circuit for each of said buses, each gate circuit being capable of operation in either of two modes of operation; b. input bias means for each gate circuit for normally operating each circuit in a different one of said modes; c. input control means for said gate circuits for comparing the voltages on said buses and applying a signed signal to both of said circuits whenever said voltages become imbalanced as a result of said fault, said signal switching the gate circuit for the faulted bus to the other one of said modes; and, d. monitoring means for said gate circuits for annunciating said switching.

Claim 3

The detector in accordance with claim 1 in which said input control means comprises a resistor network including a resistor connected between each of said buses and each of said gate circuits.

Claim 4

The invention in accordance with claim 1 wherein said input control means includes an operational amplifier the output of which varies in accordance with the nature of said ground fault.

Claim 5

A detector for indicating a resistive path to ground fault on either bus of a pair of ungrounded DC buses conducting electric power to a load, said pair comprising a positive and a negative bus, said detector comprising: a. a first and a second gate circuiT for the positive and negative bus respectively, said circuits being capable of operation in either of two modes of operation; b. input bias means for each circuit for normally operating each in a different one of said modes, one bias means inputting a positive DC signal to said first circuit and the other inputting a negative DC signal to said second circuit; c. input control means for said gate circuits for comparing the voltages on said buses and applying an additional signal to both of said circuits whenever said voltages become imbalanced as a result of a fault, a negative additional signal indicative of said fault on said positive bus switching said first circuit to the other one of said modes and a positive additional signal indicative of said fault on said negative bus switching said second circuit to the other one of said modes; and, d. monitoring means for said circuits for annunciating said switching.

Claim 6

A detector for indicating a resistive path to ground fault on either bus of a pair of ungrounded DC buses conducting electric power to a load, said pair comprising a positive and a negative bus, said detector comprising: a. a first and a second gate circuiT for the positive and negative bus respectively, said circuits being capable of operation in either of two modes of operation; b. input bias means for each circuit for normally operating each in a different one of said modes, one bias means inputting a positive DC signal to said first circuit and the other inputting a negative DC signal to said second circuit; c. input control means for said gate circuits for comparing the voltages on said buses and applying an additional signal to both of said circuits whenever said voltages become imbalanced as a result of a fault, a negative additional signal indicative of said fault on said positive bus switching said first circuit to the other one of said modes and a positive additional signal indicative of said fault on said negative bus switching said second circuit to the other one of said modes; and, d. monitoring means for said circuits for annunciating said switching.

Claim 7

The detector in accordance with claim 4 in which said input control means comprises a resistor network including a resistor connected between each of said buses and each of said gate circuits.

Claim 8

The invention in accordance with claim 4 wherein said input control means includes an operational amplifier the output of which varies in accordance with the nature of said ground fault.