Technical Articles
The switching of capacitor banks is a special and challenging task in Automatic Power Factor Correction (APFC) panels. The selection of appropriate switching device for such application is based on two criteria:
It is simple to calculate the capacitor rated current and select the switching device to be able to carry rated capacitor current (2.5 to 3 times the capacitor rated current to take care of overload, harmonics, supply voltage variation and capacitor value tolerance). However, it is a little difficult to select the switching device which is able to withstand the peak-inrush current. This is because the peak inrush current for capacitor switching application depends upon various factors such as:
- Fixed capacitor bank
- Multi-stage capacitor bank with steps of equal ratings
- Multi-stage capacitor bank with steps of unequal ratings
In multi-stage capacitor bank, the numbers and rating of steps already switched on
In most of the installations, the multi-stage capacitor banks are used as steps of unequal ratings. The bigger steps of higher kVAr ratings being switched on initially and smaller steps are switched on periodically, for achieving the targeted power factor. In such cases, the value of inrush-current peak will be far higher and hence the smaller capacitors will be heavily stressed.
Rajesh R Shirodkar,
DGM-Corporate CommunicationRajesh Shirodkar is a seasoned marketing and business leader with over 20 years of experience in the automation and electrical industry, spanning marketing communications, sales, business development, and software solution selling. He has led successful brand transformation initiatives and high-impact marketing programs, including branding and account-based marketing campaigns, as well as industry events that drive visibility, engagement, and growth. With expertise in brand building, lead generation, solution selling, and sales enablement, Rajesh is known for translating technology and business offerings into compelling value propositions and delivering sustainable growth through strong stakeholder collaboration.
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