Switch, In Particular Circuit Breaker For Low Voltages, And Power Supply For An Electronic Tripping Unit Of A Switch

A switch, comprising:

• a conductor, to run through the switch and through which current will flow;
• contact elements, each of the contact elements bearing one against another when the switch is closed, and each of the contact elements being separated from one another for the purpose of opening the switch;
• an electronic tripping unit (ETU) to trigger separation of the contact elements when a current limit value is exceeded, the ETU including a power supply, the power supply including a transformer-based current transformer arranged on the conductor, a first winding of the transformer-based current transformer, connected to the ETU, forming the secondary side of the transformer-based current transformer and the conductor forming the first primary side of the transformer-based current transformer, the conductor supplying electrical power to the ETU via the transformer-based current transformer when the current varies over time, the power supply being fed by the transformer-based current transformer, a second winding of the transformer-based current transformer, forming a second primary side of the current transformer, being arranged on a core of the transformer-based current transformer in addition to the first winding, and a converter being provided, the converter tapping off a voltage from the conductor when power is demanded and additionally supplying electrical power to the second winding.