Inrush current limiter

An inrush current limiter is a device used to limit the initial current surge that occurs when a transformer is first turned on. This surge, called inrush current, can be many times the normal operating current of the transformer and can cause damage to the power supply, wiring, and other components in the system.

An inrush current limiter works by inserting a resistor into the circuit during the initial phase of inrush to reduce the current flow and limit the inrush current to a safe level. This resistance is usually provided by a thermistor, a resistor with a temperature-dependent resistance.

These limiters are very well suited for the safe switching on of large toroidal transformers.
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An inrush current limiter is a device used to limit the initial surge of current that occurs when a transformer is first powered on. This surge of current, known as inrush current, can be many times higher than the normal operating current of the transformer and can cause damage to the power supply, the wiring, and other components in the system.

An inrush current limiter works by introducing a resistance in the circuit during the initial stages of power-up, reducing the current flow and limiting the inrush current to a safe level. This resistance is typically provided by a thermistor, which is a resistor with a temperature-dependent resistance.

The thermistor is placed in series with the primary winding of the transformer and is designed to have a high resistance at room temperature. When the power is first applied, the current flowing through the thermistor heats it up, reducing its resistance and allowing the inrush current to flow through the system.

As the temperature of the thermistor increases, its resistance decreases, limiting the amount of current that can flow through the system. Once the inrush current has passed, the thermistor cools down and its resistance increases, ensuring that the normal operating current of the transformer is maintained. In good designed limiters the thermistor is then disconnected by a relais contact, ensuring normal direct operation of the transformer. Our limiters work this way.

In summary, an inrush current limiter is an important component in a transformer-based power supply, as it helps to protect the system from the damaging effects of inrush current and ensures safe and reliable operation.

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About Rocketronics

Rocketronics was founded in 1999 as a family business by Louis Schreyer. As an engineer for microelectronics, I design hardware and also develop the software for it. We manufacture our products in-house on our own machines, and this for over 20 years now - made in Germany. In addition to the development and production, the testing of the products is also carried out here. We also manufacture the prototype construction and the test fixtures ourselves. We use lathes and milling machines for this, but we also use our 3D printers a lot. The CNC milling machines we build ourselves produce many small parts, e.g. for the housings of our controllers.

In addition to manufacturing controllers, we also trade in the necessary components. As a dealer we have a large stock of components for machine building and automation, which we offer in this store. Our suppliers are the original manufacturers, with us you buy tested branded goods. 

We also consult you when it comes to choosing the right components. We have a lot of experience in building and operating CNC milling machines and lathes. We can help you if you have questions, be it about the control system, the choice of drives or in general about the construction of CNC milling machines and the conversion of lathes. 

Our online store shows you all items available for immediate delivery, and allows you to shop securely with many payment methods and fast shipping. Data traffic is of course encrypted, payment is processed and secured by reputable service providers, and we offer a 30-day return policy

You find more about Rocketronics on our About Us Page