In the early stage of a project, does DCS have a method for estimating power?

If a UPS is to be used, have the DCS manufacturer configure it according to the specific locations.

A cabinet consumes around 100 to 200 watts of power. Next, estimate the power output required by the DO relays; just figure out how many shut-off valves there are, with each valve requiring 500 mA at 24 volts. Calculate the power needed for half of those relays. If there are 100 shut-off valves, consider 50 of them as an example. In that case, the power required by the relay amplification board would be 0.5 * 24 * 50 = 600 watts. That should give you an approximate total. It is unlikely that 50% of the cut-off valves will be open at the same time. So the measured current isn’t that high. It’s basically just an overestimation of the power

AI, AO, and DI consume very little power; it is the DO output that requires more power for amplification. There are also some instruments that are connected to the cabinet, such as mass flow meters, and these devices, which operate with independent power supply, consume a lot of power – let’s assume 20W each. If the AI devices are of the two-wire type and powered by a DCS system, the maximum current is around 20 MA; the AO devices also have a similar current level. It’s sufficient to assume 30 MA for these devices. If there are 1,000 AI and AO points, the power consumption will be 1000*0.03*24 = 720 W. DI devices consume very little power, with a current of less than 10 MA; even if it’s 10 MA, then for 500 DI devices, the power consumption will be 500*0.01*24 = 120 W. DO signals require a current of 30 MA to drive relays, but this current is only present during signal output. The most power-consuming component is the relay. When it is used to start and stop motors, it has passive contacts, and no power is supplied to the secondary side. However, when it is used to drive solenoid valves in order to open the shut-off valves, power is supplied to those valves. But generally, not all shut-off valves are opened at the same time; you can calculate the power consumption when half of them are open. In reality, such a situation of having half of the valves open does not occur. If an energy-saving solenoid valve is used, the current is only 150 MA.

Everything said upstairs is correct; we also need to consider the network cabinets, fans, lights, various engineer stations, and operation stations! Do not forget that the power cabinet supplies power to instruments that require a four-wire system, as well as to external devices that need power from it (such as online analysis instruments). Let AI check on its own – it generally knows the power consumption of a cabinet and each I/O point; it mainly depends on the type of I/O points.

If the power rating is known, the number of cabinets required can be calculated by adding the amount of redundancy to that rating. By considering the maximum output power of each cabinet module, and adding in the power consumption of cooling fans and other auxiliary devices, it is possible to determine the total power usage, which is generally very accurate

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