Pulse signals, step signals – air compressors
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Hello, I wasn’t there when the manufacturer of the air compressors used in our factory gave the explanations; there are some design flaws. Every time a fault causes a shutdown, it’s necessary to manually reset the two remote start/stop relays located in the air compressor cabinet, otherwise remote start/stop will not work again. I heard someone explain that DCS sends pulse signals, while the pressure controller receives step signals; that’s why two relays were added. I would like to ask why, every time the air compressor trips due to a high exhaust temperature, it is necessary to remove and reinsert those two relays. What is the reason for this? Is there a better way to solve this problem?
Without the on-site data from you, no one else can answer this question. It’s the 21st century already, and we still need to manually insert and remove relays – it shows just how stupid the manufacturers’ staff are.
The manufacturer said it would be more convenient to make the changes in the DCS, but the DCS manufacturer wasn’t willing to do that, and that’s how it ended up. I just want to ask how people make these changes in the DCS, so that I can prepare a reasonable proposal
Those two relays form an RS flip-flop; when a start pulse signal is applied to the set terminal, the output remains as a step signal. However, to reset an RS flip-flop after it has been triggered, a pulse signal needs to be applied to its reset terminal. I think it is because no reset signal is provided that the RS flip-flop cannot be reset; that’s why it is necessary to manually disconnect it in order to restore its contacts to an open state