Single-phase electricity: I=P/U/cosφ
I is the rated current.
U is rated voltage.
Cosφ is the power factor.
For purely resistive loads, such as incandescent lamps and electric furnaces, cosφ can be 1. If the load power factor is unknown, it can be estimated as 0.8.
Question 2: Calculation method of line load: The branch line load is 1.5―― 1.8 times the starting current of the load.
Trunk load is: 1.5―― 1.8 times the sum of load starting current and running electrical equipment current.
Question 3: How to calculate the average load? For example, a month's electricity consumption is 300 kWh, and the average daily load is 300 divided by 30 days, that is, the average daily load of the month is 10 kWh.
Question 4: How to calculate the equipment load? 50 points Guo Dun replied:
Normal working hours are 1 day for 20 hours. The peak time is 1 day for 24 hours, the average daily time is 2 1 hour, and the average monthly time is 26.5 days. Then, the equipment should be operated once a month.
26.5×2 1=556.5 (hours),
15000/556.5=27 (pieces/hour)
The equipment load is 27 per hour.
What is human load? Let's do a calculation.
365 days a year;
52 weeks in the whole year, weekend 104 days, national legal holidays: New Year's Day 1 day, Spring Festival 3 days, May Day 1 day, Tomb-Sweeping Day, Dragon Boat Festival, Mid-Autumn Festival 1 day, National Day 2 days * *1.
The annual working days are (365- 1 15) = 250 days, and the average monthly working days are 250/ 12=2 1 (days);
It is legal to work 8 hours a day, and the average legal time for employees to work every month is 2 1×8= 168 (hours).
(company or enterprise regulations) employees will work in two shifts. Normal working hours are 1 day for 20 hours. The peak period is 1 day for 24 hours. If 26.5 days count as a month, then each employee works 10 .5 hours a day and 2 days a month, then the working time of the whole month is 26.5× 105=278.25 (hours), or the following calculation is made:
The legal monthly working hours of the whole people are 168 hours, and the monthly working hours of employees (specified by companies or enterprises) are 278.25 hours.
Workload of employees (company or enterprise) = 278.25/168×100% =165.6%! ! !
This was before 120! !
Before 120, on May 1886, Chicago workers held a meeting to force capitalists to implement the eight-hour working system. After a hard and bloody struggle, we finally won. In order to commemorate this great workers' movement, in July 1889, the Second International announced that May 1 day every year would be designated as International Labor Day. China has also designated May Day as Labor Day, and now it implements the weekend system. However, many companies or enterprises do not implement the laws and regulations of the state in this regard, and the state does not interfere. In fact, it is the default of those unscrupulous companies to squeeze employees and earn the most profit!
In the early days of western capitalism or for a long time afterwards, workers still had their own trade union organizations. However, in many companies or enterprises in China, employees did not have their own trade union organizations, and some of them only served in disguise, failing to safeguard the interests of employees.
1886, 1 In May, when the workers in Chicago held a conference, an "Eight Hours Song" was popular among the workers in * * *, which sang:
"We want to change the world. We are tired of futile toil, we only earn a living, so we never have time to think. We want to smell the flowers, we want to bask in the sun, and we believe that God only allows eight-hour working days. We gathered our teams from docks, workshops and factories to strive for eight hours of work, eight hours of rest and eight hours for ourselves! "
What kind of sound can our employees make!
Question 5: Load calculation methods for calculating load There are several methods for load calculation, such as demand coefficient method, utilization coefficient method and unit index method. Need coefficient method. Multiply the equipment power by the demand coefficient and the simultaneous coefficient, and directly calculate the calculated load. This method is simple and widely used, especially suitable for load calculation of distribution network and substation. Use the coefficient method. Use this coefficient to calculate the average load of the maximum load level, and then consider the influence of the number of equipment and power difference, multiply the maximum coefficient related to the effective number of equipment to get the calculated load. The theoretical basis of this method is probability theory and mathematical statistics, so the calculation results are close to reality. It is suitable for load calculation in various ranges, but the calculation process is a little complicated. Unit area power consumption method, unit index method, unit product power consumption method. The former two are mostly used in civil buildings, while the latter is used in some industrial buildings. These methods are the main methods to determine the equipment load when the power and quantity of electrical equipment cannot be determined, or at the initial stage of design. In addition to the above methods, binomial method, abc method and variable value demand coefficient method have appeared in China in recent years. Some of these methods are replaced by other methods, some are simplified by coefficient method, and some have little practical data, so they cannot be popularized. Power per unit area method, unit index method and unit product power consumption method are mostly used in the preliminary calculation of design, such as feasibility study and scheme design stage; Demand coefficient method and utilization coefficient method are often used in preliminary design and construction drawing design.
Question 6: How to calculate the hydraulic load and what is the formula? The main design parameters of constructed wetland should be determined according to the test data; If there is no test data, you can use empirical data, or take values according to the data in line HJ2005-20 10 (including the hydraulic load you mentioned).
Question 7: Calculation method of heat load Hello, give a brief answer:
It is clearly stipulated in the specification that when the temperature difference between adjacent rooms is greater than or equal to 5℃, or the heat transfer through the partition wall and floor is greater than 10% of the room heat load, the heat transfer through the partition wall or floor should be calculated, and the heat transfer calculation formula refers to the heat consumption calculation of the enclosure structure. According to the code, the correction rate of orientation should consider the local winter sunshine rate, building use and occlusion. In areas with sunshine rate less than 35% in winter, the correction rates of southeast, southwest and south should be-10%~0, and the correction rates of east and west are not required. So, if you describe that the sun is blocked, please refer to the above description. The revision of the specification is not just about the four directions of east, west, north and south. It is recommended to look at it carefully.
Does the elevator shaft need heating? Need to calculate the heat load? That's news to me.
Question 8: How to calculate the electricity load? 5 points: Add all the electricity loads together *0.8 or 0.75, and the operation coefficient is the electricity load you calculated. This is a rough algorithm, and there are many parameters for calculating power load in the design.
Question 9: How to calculate the load? Demand coefficient method for calculating load
1. Equipment capacity of equipment group
When the demand coefficient method is adopted, the electrical equipment should be grouped by type, and the electrical equipment of the same type should be combined together to calculate the equipment capacity of this group of electrical equipment.
For long-term power load (such as air conditioning unit, etc.). ), the equipment capacity is the rated power marked on the equipment nameplate.
For intermittent periodic electrical equipment, its equipment capacity is
Lighting equipment: the equipment capacity of incandescent lamp is taken according to the rated power marked on the bulb; Due to the influence of self-inductance ballast, the lighting equipment such as fluorescent lamp and high-pressure mercury lamp with self-inductance ballast not only has low power factor, but also needs to consider the power consumption of ballast when calculating the equipment capacity. Therefore, the equipment capacity of fluorescent lamp device with self-inductance ballast is 1.2 times the rated power of lamp tube, and that of high-pressure mercury lamp device is 1. 1 times the rated power of bulb.
2. Calculation load of electrical equipment group
According to the equipment capacity of the electrical equipment group, the calculated load of the equipment can be calculated:
Active calculation load (12- 1)
Reactive power calculation load
Apparent calculation load
or
Calculated current (12-2)
Where-demand coefficient of equipment group;
—— Equipment capacity of equipment group (kW);
-Power factor angle of electrical equipment;
U line voltage (v);
-calculate the current (a).
The above formula is suitable for calculating the calculation load of three-phase electrical equipment group, and the calculation current of formula (12-2) is particularly important, because the calculation current is an important basis for selecting the conductor cross-sectional area and switching capacity.
For single-phase electrical equipment, it can be divided into two situations:
The rated working voltage of (1) phase load is the phase voltage. During normal operation, the phase load is connected between the live line and the neutral line, and most single-phase electrical equipment and household appliances in civil buildings belong to the phase load. In the design of power supply and distribution, the phase load should be evenly distributed among the three phases as much as possible, and the equivalent three-phase equipment capacity can be obtained by multiplying the largest single-phase equipment by 3, and then the calculated current (line current) can be obtained according to the above formula.
-Single-phase equipment capacity at maximum load stage
(2) Line-to-line load Line-to-line load refers to a single-phase electrical load whose rated working voltage is line voltage. During normal operation, the load between lines is converted into equivalent phase load, and then the calculated current is obtained according to the phase load.
Capacity of single-phase equipment connected to line voltage
3. Calculation load of distribution trunk line or substation
A plurality of electrical equipment groups grouped by type are connected to the low-voltage bus of the distribution trunk line or substation. Considering that each electrical equipment group is not operating under the maximum load at the same time, the calculated load of the distribution trunk or substation should be equal to the sum of the calculated loads of each electrical equipment group, and then multiplied by a simultaneous coefficient, that is, the calculated load on the low-voltage bus of the distribution trunk or substation is:
Active computing load
Reactive power calculation load (12-3)
Apparent calculation load
Calculated current (12-4)
The simultaneous coefficients of active power and reactive power are generally 0.8 ~ 0.9 and 0.93 ~ 0.97;
-Sum of active calculated loads of each electrical equipment group (kW);
-sum of reactive power calculation loads of each electrical equipment group (kvar);
U- rated line voltage of electrical equipment (V).
It should be noted that due to the different types of electrical equipment groups, their power factors are also different. Therefore, in general, the total apparent calculation load cannot be calculated, and the total apparent calculation load or current cannot be used as the sum of the current calculation load or current of each group of electrical equipment.
4 Selection of demand coefficient
Demand coefficient is obtained by statistical method under certain conditions, which is related to the working nature, equipment efficiency, equipment quantity, line efficiency, production organization and process design of electrical equipment. & gt