Voltage bus protection and isolation device

A voltage bus protection and isolation device comprising:

• a bus supply voltage input terminal;
• a bus supply voltage output terminal;
• a bus supply disconnect circuit connected between the bus supply voltage input terminal and the bus supply voltage output terminal;
• a gate drive circuit connected to the supply bus disconnect circuit;
• an over voltage monitoring circuit connected to the bus supply voltage input terminal;
• an under voltage monitoring circuit connected to the bus supply voltage input terminal;
• a resistive circuit connected between a first bus supply return terminal and a second bus supply return terminal;
• a current sensing circuit connected to the resistive circuit;
• a current squared time (I2t) comparison circuit connected to the current sensing circuit;
• a control circuit connected to a control terminal;
• a fault latch circuit connected to the over voltage monitoring circuit, the under voltage monitoring circuit, the gate drive circuit, the current squared time (I2t) comparison circuit and the control circuit, wherein the fault latch circuit:
• (a) turns the bus supply disconnect circuit “OFF” via the gate drive circuit thereby isolating the bus supply voltage input terminal from the bus supply voltage output terminal whenever the over voltage monitoring circuit detects an over voltage condition, the under voltage monitoring circuit detects an under voltage condition, the current squared time (I2t) comparison circuit detects an overload condition or an “OFF” signal is received from the control circuit, and (b) turns the bus supply disconnect circuit “ON” via the gate drive circuit thereby connecting the bus supply voltage input terminal to the bus supply voltage output terminal whenever an “ON” signal is received from the control circuit;
• and
• a data process monitoring circuit connected to the over voltage monitoring circuit, the under voltage monitoring circuit, the fault latch circuit, the current sensing circuit, the bus supply voltage output terminal, the second bus supply return terminal and one or more data terminals.

A method for protecting and isolating a voltage bus comprising the steps of:

• providing a device comprising a bus supply voltage input terminal, a bus supply voltage output terminal, a bus supply disconnect circuit connected between the bus supply voltage input terminal and the bus supply voltage output terminal, a voltage monitoring circuit connected to the bus supply voltage input terminal, a resistive circuit connected between a first bus supply return terminal and a second bus supply return terminal, a current squared time (I2t) monitoring circuit connected to the resistive circuit, a control circuit connected to a control terminal, and a fault latch circuit connected to the voltage monitoring circuit, the bus supply disconnect circuit, the current squared time (I2t) monitoring circuit and the control circuit;
• measuring an input supply voltage using the voltage monitoring circuit;
• measuring a current squared time (I2t) value based on a current across the resistive circuit using current squared time (I2t) monitoring circuit;
• automatically turning the bus supply disconnect circuit “OFF” using the fault latch circuit thereby isolating the bus supply voltage input terminal from the bus supply voltage output terminal whenever the voltage monitoring circuit detects an over voltage condition, the voltage monitoring circuit detects an under voltage condition, the current squared time (I2t) monitoring circuit detects an overload condition or an “OFF” signal is received from the control circuit;
• and
• automatically turning the bus supply disconnect circuit “ON” using the fault latch circuit thereby connecting the bus supply voltage input terminal to the bus supply voltage output terminal whenever an “ON” signal is received from the control circuit.