Integrated active isolation measurement

A power distribution system comprising:

• a power supply configured to supply a load with power, wherein the power supply and load are isolated from a chassis ground for the power distribution system;
• an isolation measurement circuit comprising:
• a measurement resistor;
• measurement circuitry connected across the measurement resistor;
• a first switch connecting a first isolation resistor to a first terminal of the measurement resistor, wherein the first isolation resistor also connects to a positive bus of a power distribution system such that the first switch is connected on a lower voltage side of the first isolation resistor;
• a second switch connecting a second isolation resistor to a second terminal of the measurement resistor, wherein the second isolation resistor also connects to a negative bus of the power distribution system such that the second switch is connected on a lower voltage side of the second isolation resistor;
• and
• a pulse generator that connects the measurement resistor to the chassis ground.

A method comprising:

• controlling a switch to connect a bus of a power distribution system to a first terminal of a measurement resistor, wherein the bus connects to the first terminal of the measurement resistor through an isolation resistor such that the switch is connected on a lower voltage side of the isolation resistor;
• applying, by a pulse generator of an isolation measurement circuit, a pulse between a chassis ground and a second terminal of the measurement resistor;
• and
• measuring, by measurement circuitry connected across the measurement resistor, a value across the measurement resistor, wherein the value measured across the measurement resistor comprises an indication of an isolation resistance between a chassis ground and the bus when the switch is conducting and the pulse generator delivers the pulse.