Calculations related to electrical load
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I work in the field of manufacturing processes. Below is the calculation of electrical load done by the design institute; it’s not very clear to me. I’m seeking help from those who work in electrical engineering – how exactly is this calculation carried out? The main electrical equipment in a certain air separation system includes: one cooling tower motor with a power of 110 KW ； Cooling water pump motor power = 110 KW, three units (two in use and one as backup); there is also a small motor of 0.75 KW and another of 0.37 KW. The calculation results are: Pe=2100kW, Pj=1989kW, Qj=1119kVAR (the load calculated at 0.4 kV is adjusted to the 6 kV side), SJ=2282kVA, and cosφ=0.87
Based on the data you provided, this calculation result should represent the total capacity of the high-voltage side of the transformer, and not just the capacity of those devices in the air separation system.
1. Your system is an expansion version, or it shares a substation with other devices. 2. The calculation results are as follows: Pe=2100kW----------------------------------------Rated installed capacity; Pj=1989kW---------------------------------------------Active load (I think the value he calculated is too high). Qj=1119kVAR (the load at 0.4 kV is converted to the 6 kV side)---------Reactive load. SJ=2282kVA-------------------------------------Apparent power; cosφ=0.87----------------------------------------------Power factor. 3. The power of the cooling tower motor is 110 KW per unit ； Cooling water pump motor power = 110 KW, three units (two in use and one as backup); there is also a small motor of 0.75 KW and another of 0.37 KW. The calculated load for this set of equipment has been determined primarily based on the rated load. Because there are too few devices. But there is a question that can be explored here. The standby circuit with 2 in operation and 1 as backup is generally not included in the calculated load. However, given that the motor is large and difficult to start, as well as the requirements related to pump switching in the process (whether to start or stop first), if there are difficulties with this standby circuit, it needs to be taken into account in the calculated load.
Why are you, who works in manufacturing, asking this? Lol – you don’t even know the overall preliminary design plan; there’s a reason behind what they do.
Why are you, who works in manufacturing, asking this? Lol – you don’t even know the overall preliminary design plan; there’s a reason behind what they do.
Thank you, senior on the third floor. Could you provide the calculation process or formula? I want to know how it’s calculated exactly
Thank you! ! I’ve learned it! !
Pe: The rated power of electrical equipment, which is obtained by adding up the powers of various devices; standby power is not included in this value. Pj: The calculated load, which is equal to Pe multiplied by a demand factor. The value of this demand factor depends on the type of load, with values typically ranging from 0.65 to 0.8. Sj = Pj/cosφ, and QJ = PJ*tanφ
The power design manual contains a full set of formulas and calculation examples!