Motor drive assembly

1. A system comprising:

a discharge sensor configured to measure a parameter indicative of an electrical current in an electrical insulator of an electrical conductor; and

a voltage controller for being connected to the discharge sensor for controlling a voltage signal applied to the electrical conductor based on a value of the parameter measured by the discharge sensor;

wherein the voltage controller is configured to control the rate of change of amplitude of the voltage signal applied to the electrical conductor with time (dV/dt) based on the value of the parameter measured by the discharge sensor: and

wherein the voltage controller is configured to decrease said rate (dV/dt) if the value of the parameter measured by the discharge sensor is above a first set-point value and/or to increase said rate (dV/dt) if the value of the parameter measured by the discharge sensor is below a second set-point value.

2. The system of claim 1 , comprising an environment sensor for sensing one or more parameters of the environment in which the electrical insulator is located; wherein the system is configured to set said first and/or second set-point value based on the value of the one or more parameters of the environment.

3. The system of claim 2 , wherein the one or more parameters of the environment is one or more of: pressure, temperature and humidity.

4. The system of claim 2 , comprising a dV/dt sensor arranged and configured to determine the rate (dV/dt) output from the voltage controller to the electrical conductor and generate a feedback signal in response thereto, wherein the feedback signal is fed back to the voltage controller for regulating the rate (dV/dt) of the voltage output to the electrical conductor.

5. The system of claim 4 , wherein the voltage controller comprises a signal limiter for limiting the rate (dV/dt) to be between a minimum non-zero threshold value and/or a maximum threshold value.

6. The system of claim 1 , wherein the voltage controller comprises an output connected to the electrical conductor, a first switch for connecting a first DC voltage terminal to the output when closed, and a second switch for connecting a second DC voltage terminal to the output when closed; wherein the voltage controller is configured to alternately open and close each of the first and second switches for providing an AC voltage signal to said output and winding.

7. The system of claim 6 , wherein the first switch and/or second switch comprises a transistor that is opened and closed by varying a switching voltage applied to the transistor; and wherein the voltage controller is configured to vary the rate at which the switching voltage increases or decreases during opening or closing of the switch as a function of time based on the electrical value of the parameter measured by the discharge sensor.

8. The system of claim 6 , wherein the voltage controller comprises a signal limiter for limiting the rate (dV/dt) to be at or above a minimum non-zero threshold value; the system comprising a temperature sensor for sensing a temperature of the first and/or second switch in the voltage controller, or a surrounding environment, and being configured to vary the minimum threshold value based on the sensed temperature.

9. The system of claim 6 , wherein the voltage controller is configured to control the rate of change of amplitude of the voltage signal applied to the electrical conductor with time (dV/dt) based on the value of the parameter measured by the discharge sensor; wherein the system comprises a temperature sensor for sensing a temperature of the first and/or second switch in the voltage controller, or a surrounding environment, and wherein the system is configured to prevent the rate (dV/dt) being reduced if said temperature exceeds a predetermined maximum value.

10. The system of claim 1 , comprising: the An assembly comprising an electrical conductor and the electrical insulator for electrically insulating the electrical conductor, wherein the discharge sensor is arranged in, on or proximate the electrical insulator.

11. A motor or actuator comprising the assembly system of claim 1 .

12. A method of installing the system of claim 1 , comprising: arranging the discharge sensor in, on or proximate the electrical insulator of an electrical conductor; and connecting the voltage controller to the discharge sensor.

13. A motor system comprising:

an electrical conductor in the form of a coil or winding;

an electrical insulator insulating the electrical conductor;

a discharge sensor arranged and configured to measure a parameter indicative of an electrical current in the insulator; and

a voltage controller for controlling a voltage signal applied to the electrical conductor based on a value of the parameter measured by the discharge sensor;

wherein the voltage controller is configured to control the rate of change of amplitude of the voltage signal applied to the electrical conductor with time (dV/dt) based on the value of the parameter measured by the discharge sensor: and

wherein the voltage controller is configured to decrease said rate (dV/dt) if the value of the parameter measured by the discharge sensor is above a first set-point value and/or to increase said rate (dV/dt) if the value of the parameter measured by the discharge sensor is below a second set-point value.