Brand new technology completely eliminates inrush current
Inrush current is a recognised issue for many types of electrical equipment, and it must be managed to guarantee the safety and long-term reliability of any installation. In this article, we’ll explore the cause of inrush current, traditional ways of managing it and how Pulsiv OSMUIM technology has eliminated the problem.
What is inrush current?
Simply put and as the name suggests, inrush current is a surge of current that enters an electrical device when power is first applied. Although it only occurs for milliseconds, inrush current can be 40-80 times higher than the steady-state operating current for which a system may have been originally designed. This is particularly challenging where many units are connected together and powered-up simultaneously (LED lights, servers, EV chargers, alarms, and air conditioners etc.) or in scenarios where future expansion is possible. If ignored, the consequences can be catastrophic. Inrush current causes blown fuses, damaged circuit breakers, welded relay contacts and major service interruptions.
What causes inrush current?
All legacy AC to DC power supply designs will contain storage components (capacitors, inductors, and transformers) that naturally draw a significant amount of energy during the start-up phase. Traditional power electronic circuits provide a low resistance path that allow large currents to flow. Think of it like trying to move a large heavy object – to start with, a huge amount of energy is needed to move it, but less once there’s some momentum. Steps must be taken to avoid the potential consequences in systems exhibiting this behaviour.
How is inrush current managed today?
Various methods are available, but all come with their own compromises. Some involve the use of specialist components in the power supply design (ohmic resistor, NTC thermistor, PTC thermistor or a soft start circuit), which introduce cost, complexity, and energy waste. In cases where the power supply design does not actively manage inrush current, system installers must upgrade circuit breakers or limit the number of LED drivers, power supplies or battery chargers that are connected to a single wiring circuit (adding time and cost).
How has Pulsiv eliminated Inrush Current?
In a conventional power supply design, a series inductor is used to achieve Power Factor Correction (PFC). Pulsiv has developed and patented a completely different method by charging a capacitor in parallel. This approach enables greater control and prevents a large current from flowing into the circuit. When measured using accepted techniques, Pulsiv OSMIUM designs have been proven to completely eliminate inrush current.
Explains CEO Darrel Kingham: “Inrush current has always been a problem in certain applications due to the behaviour of legacy power electronics. The obvious safety and reliability implications mean that it must be addressed somewhere in the system design or installation process. By completely eliminating inrush current, Pulsiv OSMIUM technology reduces cost, complexity, and risk in any application where it currently needs managing”
Launched in September 2022, Pulsiv OSMIUM technology provides manufacturers with a cost-effective method of designing always efficient power supplies to reduce overall energy consumption while delivering a range of other benefits. It offers engineers complete flexibility to adapt and scale for virtually any application from just 20W to several kW, with evaluation boards and document packages available online to simplify the design process.
What are the benefits of no inrush current?
It goes without saying that a circuit without inrush current offers significant advantages:
Design Phase:
- Overall system design is simplified
- Reduction in component count, PCB space and assembly time
- A scalable solution for different applications
End Applications:
- Reduce manufacturing costs
- Improve reliability
- Extend product lifetime
Installations:
- System installation is simplified
- Reduction of cabling
- Installation time/cost reduced
Fire alarm system example
In a typical fire detection system used for large commercial buildings, there will be several notification devices on a 24Vdc circuit that may be several kilometres long. Due to strict regulations, it is not possible to increase voltage or add equipment to address voltage drops caused by inrush current. Output lines from the fire panel are protected, so the combined effect of inrush from multiple devices can cause fuses to blow and complete system failure. Sounder manufacturers do not always document inrush current data for their devices, so the problem is often discovered and resolved during installation.
About Pulsiv
Founded in 2013 as a spin out from the University of Plymouth (UK), the company has developed technology to improve the efficiency of power electronics used in mains powered and battery charging applications as well as enabling more energy to be extracted from solar panels. Pulsiv is committed to helping the world transition to renewable energy and reducing the impact that electronic devices have on the environment.
Useful links:
What is Pulsiv OSMIUM technology click here
Pulsiv OSMIUM microcontrollers click here