Reducing transformer inrush current

A controller comprising:

• processing circuitry;
• and
• data storage storing instructions executable by said processing circuitry whereby said controller is operative to perform a method of operating a switching device arranged between an AC voltage source and a transformer in an electrical three-phase system, the method comprising:
• between the switching device and the voltage source, monitoring a voltage in one of the phases;
• operating the system at each of a plurality of system configurations;
• for each of the system configurations and a predetermined same opening angle relative to a reference angle of the monitored voltage, determining a suitable closing angle relative to the reference angle and storing information about said determined suitable closing angle in association with the system configuration in a database;
• determining a system configuration in the system;
• at the predetermined same opening angle, opening the switching device;
• from the database, obtaining a closing angle of said determined suitable closing angles, wherein the system configuration with which the obtained closing angle is associated in the database corresponds to the determined system configuration;
• and
• at the obtained closing angle, closing the switching device.

A switching device comprising:

• a controller having:
• processing circuitry;
• and
• data storage storing instructions executable by said processing circuitry whereby said controller is operative to perform a method of operating the switching device arranged between an AC voltage source and a transformer in an electrical three-phase system, the method comprising:
• between the switching device and the voltage source, monitoring a voltage in one of the phases;
• operating the system at each of a plurality of system configurations;
• for each of the system configurations and a predetermined same opening angle relative to a reference angle of the monitored voltage, determining a suitable closing angle relative to the reference angle and storing information about said determined suitable closing angle in association with the system configuration in a database;
• determining a system configuration in the system;
• at the predetermined same opening angle, opening the switching device;
• from the database, obtaining a closing angle of said determined suitable closing angles, wherein the system configuration with which the obtained closing angle is associated in the database corresponds to the determined system configuration;
• at the obtained closing angle, closing the switching device, and a sensor for the monitoring of the voltage.

An electrical system comprising:

• a controller having:
• processing circuitry;
• and
• data storage storing instructions executable by said processing circuitry whereby said controller is operative to perform a method of operating a switching device arranged between an AC voltage source and a transformer in the system, the system being an electrical three-phase system, the method comprising:
• between the switching device and the voltage source, monitoring a voltage in one of the phases;
• operating the system at each of a plurality of system configurations;
• for each of the system configurations and a predetermined same opening angle relative to a reference angle of the monitored voltage, determining a suitable closing angle relative to the reference angle and storing information about said determined suitable closing angle in association with the system configuration in a database;
• determining a system configuration in the system;
• at the predetermined same opening angle, opening the switching device;
• from the database, obtaining a closing angle of said determined suitable closing angles, wherein the system configuration with which the obtained closing angle is associated in the database corresponds to the determined system configuration;
• at the obtained closing angle, closing the switching device,
• the switching device, and
• the transformer.

A computer program product comprising computer-executable components which, when run on processing circuitry included in a controller, causes the controller to perform a method of operating a switching device arranged between an AC voltage source and a transformer in an electrical three-phase system, the method comprising:

• between the switching device and the voltage source, monitoring a voltage in one of the phases;
• operating the system at each of a plurality of system configurations;
• for each of the system configurations and a predetermined same opening angle relative to a reference angle of the monitored voltage, determining a suitable closing angle relative to the reference angle and storing information about said determined suitable closing angle in association with the system configuration in a database;
• determining a system configuration in the system;
• at the predetermined same opening angle, opening the switching device;
• from the database, obtaining a closing angle of said determined suitable closing angles, wherein the system configuration with which the obtained closing angle is associated in the database corresponds to the determined system configuration;
• and
• at the obtained closing angle, closing the switching device.