How to understand a dual-powered supply?
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I would like to ask: In HG/T20509-2014, under section 5.3.4, for measuring and control instruments equipped with dual power supplies, when they are powered by both a UPS and another separate conventional power source, it is advisable to use an isolation transformer for the conventional power source. ”How should we understand the dual-powered supply here?
There are two power supply routes; what’s not clear about this?
A dual power supply means that when one of the power sources fails, the other should not be damaged as well, but should be able to continue supplying power!
It refers to a single instrument, or a set of instrument systems, that is capable of receiving power from two sources. (Separate meter; two power circuits are less common)
A measuring and control instrument or device can receive power from two sources simultaneously; in the event of a failure in one source, the other source can still ensure the normal operation of the instrument. This notion of duality is most likely the result of mechanically translating foreign materials.
This dualization corresponds to multiplexing, meaning two power supplies, with the backup supply being activated automatically. If the instrument operates on direct current, a simple approach is to provide two DC supplies that share either the negative or positive terminal, and then use the one-way conductivity of diodes to supply power in parallel, ensuring that if one supply fails, the other can still supply power to the instrument without any problems. When there are more than two circuits, it is called multiple power supply. In this case, when a UPS and a regular power supply are used as backups, an isolation transformer is installed on the regular power supply, primarily to prevent grounding current issues. Some UPS units are not isolated from the mains power internally.