How does a PLC achieve dual power supply from mains electricity and UPS?
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How does a PLC achieve dual power supply from both the mains and a UPS, and what is needed to provide isolation in between?
1. A redundant power supply module can be used for 24VDC； 2. 220VAC can be handled using AC quick-switching equipment.
An online UPS is used; the mains power is also connected to the UPS and supplied through its output. In the event of a power outage, it can switch seamlessly to battery power, while in the case of a UPS failure, it can automatically switch to bypass mode. As for the type of isolation to be used between the mains power and the UPS, it mainly depends on whether the mains power at the site is \"clean\" and free from excessive harmonic interference ； Sometimes only a simple isolation transformer is needed, while sometimes an active filter is required.
There is a question: when the UPS is working properly, it outputs power from the mains; it only switches to the battery in case of a power failure, at which point there is no mains power available. Therefore, switching between the UPS and the mains power is meaningless, unless you have another independent source of mains power.
Just like we use multiple laptops, the battery and power supply provide power simultaneously