The issue of single-bus sectional power supply in the low-voltage distribution systems of petrochemical enterprises
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1. In the low-voltage power distribution systems of petrochemical enterprises, a single busbar with segmented power supply is generally used. Two transformers are employed, and in the design, it is common practice to place the two motors – one in service and one as a backup – in separate sections; that is, the motor in regular use is placed in section I, while the backup motor is placed in section II. In that case, it’s as if only one transformer is in operation, and it’s running at full capacity, while the other transformer has almost no load – doesn’t this violate the principles behind choosing two transformers? 2. For installations with a low electrical load, such as those below 1000 KVA, is it still necessary to use two transformers for segmented power supply via a single busbar? Isn’t that quite a waste? How is single-bus sectionalized power supply achieved? Because the design codes for power systems in petrochemical enterprises stipulate that a single busbar with sectionalization should be used for 0.38 kV supply systems.
The poster is from a design institute, right? They don’t have any experience in actual operation on site! In a single-mother sectional wiring configuration, how could the entire load be on one section? If one unit is in use and one is in standby, then for this load (such as a feed water pump), unit A operates while B remains in standby. For another load (such as the desalination water pump), B operates while A is in standby, thereby spreading the loads out. In the second phase, there are actually many devices with two in operation and one as backup on site, which achieves a better balance! A single-mother sectional wiring scheme is adopted, with two transformers used to supply power respectively. This approach is not intended to address issues of urgency or waste; rather, it takes into account the fact that the electrical loads in petrochemical enterprises are generally of class II or even class I, requiring dual-power supply!
They generally serve as backups for each other, with no fixed primary or secondary one. So it is still very likely that extreme situations will occur, with one bus bar being fully loaded. Another segment is idle. I’m as confused as the original poster. Please ask the moderator to help explain it too
I think it is mainly designed for production in the chemical industry, with single-bus power supply to reduce the impact of failures. In our factory, when a transformer fails, production has to be reduced and power supply is provided by using just one busbar.
Single-bus sectionalization also has different operating modes; if the high-voltage power supply is in hot standby, the low-voltage transformers can operate in parallel, allowing for even load distribution. If the high-voltage power supplies are used as backups for each other, the low-voltage busbars should operate in sections. In fact, when designing, it was taken into account that in the event of a failure in one power supply or transformer, the other power supply or transformer can handle the entire load of the busbar. So the transformer capacity is sufficient. It simply cannot guarantee the economic efficiency of the transformer’s operation.
The chemical industry places a strong emphasis on safety; generally, pumps are designed to operate in a one-in-use and one-backup configuration, or in a two-in-use and one-backup configuration