Per unit calculation examples pdf

In per unit, base conversion is a normal part of the calculation method while in ohmic method, complex entities conversion. It is a ratio of the number of defects over the number of units tested. Power system analysis lectures examples on reactance diagram and pu calculation. The per unit system overview page 1 of 6 overview the per unit system is based on the formula shown in equation 1. It is most commonly measured as net income divided by the original capital cost of the investment. Singlephase per unit system university of texas at. These calculations shall govern the structural portion of the working drawings.

Markup percentages are especially useful in calculating how much to charge for the goodsservices that a company provides its. Per unit system for the analysis of electrical machines or electrical machine system, different values are required, thus, per unit system provides the value for voltage, current, power, impendence, and admittance. Imagine a 3phase system with a generator, a transformer, a tline, another transformer, and a load. To use the per unit method, we normalize all the system impedances and admittances. In a throughput accounting context, a very similar calculation is. Per unit calculation per unit system examples electrical. Earnings per share are almost always analyzed relative to a companys share price.

The normalization typically follows transformer ratings. Hence, average cost equals average fixed cost plus average variable costs. As an example of how perunit is used, consider a threephase power transmission. The calculations using the per unit system are simplified.

Besides being taught in higher education, it is quite commonly used by engineers in the power industry. The below table shows the calculation of the holding cost. Calculate the per unit impedance for transformer t1. In simple terms, breakeven point is where there is neither profit nor loss in a companys operation. A perunit value is the actual value of some quantity divided by the base value of that quantity. Perunit and primarysecondary calculations perunit basics a perunit value is the actual value of some quantity divided by the base value of that quantity. This appendix presents standards and guidelines for electrical design calculations for spu projects. Example seismic analysis and design of a six storey building problem statement. Information for a small power system is shown below. For example, the series resistance is usually from 0. Here are the main reasons for using the per unit system.

Perunit method allows the same basic arithmetic operation resulting in perphase end values, without having to worry about the factor 100 which occurs in per cent system. Variable costing formula calculator excel template. Calculation of equivalent dwelling units edus the purpose of this worksheet is to determine edus for rd funding determinations only. For example, a transient voltage reaching a maximum of 1. Introduction to perunit systems part 1b per unit system.

Learn more in cfis guide to the priceearnings ratio price earnings ratio the price earnings ratio pe ratio is the relationship between a companys stock price and earnings per share. Use base value of 30 kva and 240 v in zone 1, draw per unit circuit and find per unit value of source voltage and all impedances. With transformers, we need to convert the voltage magnitudes,impedances, currents, etc. As you can see there are a lot of things to factor in. Per unit identities university of minnesota duluth. It is different from the traditional measurement of yield. Chapter 259 u charts introduction this procedure generates the u control chart for the number of nonconformities per unit, based on the number of nonconformities per sample. Rather determined per unit values serve to assist in the calculation of other system values. Calculations are simplified because quantities expressed as perunit do not change when they are referred from one side of a transformer to the other. Eoq definition, formula calculate economic order quantity. In the above steadystate equation, time does not appear explicitly. To gain a better understanding, it is worth running through the typical steps required to solve a fault calculation problem. Fault current calculations the base current of the generator can be computed as, 0 4 0 e e e s ia v the subtransient, transient, and steadystate currents are per unit and amps 1. Per unit calculations a key problem in analyzing power systems is the large number of transformers.

This makes the per unit value of either voltage or current to be around 1. It may or may not correlate with existing or proposed billing practices. Neutral size is assumed to be the same size as the phase conductors. The unit of energy is the joule, the unit of power is the watt, and the unit of time is the second. Its reactances per unit to the machines own base are x s 2 and the time constants are s4. Per unit example how to, tips, tricks, and what to watch out for. A six storey building for a commercial complex has plan dimensions as shown in figure 1. For the u chart, the value for u can be entered directly or u can be. Generally base values of power and voltage are chosen. When all impedances in a multivoltage power system are expressed on a common power base and on the nominal voltages of the different subnetworks, the total impedance in pu seen at one bus is obtained by simply adding all impedances in pu, without taking into consideration the. In this example, there are two transformers that divide the system into three different voltage zones that are created by the stepping. Therefore, a 1 mw power plant will produce kilowatts per hour. The eqn 1 show that the per unit impedance is directly proportional to base megavoltampere and. The capacitance c increases linearly with the area a since for a given potential difference.

Assume that no current is flowing in the network, so that all generator and motor voltages are. Elec0014 introduction to power and energy systems the. Examples of absorption costing formula with excel template absorption costing formula. By using per unit calculations that different voltage bases but the same powerbase are used in different transformer sections. Vin per unit vin kvv base in kv where the base value is a reference value for magnitude. Cost per unit can be defined as the amount of money spent by the company during a time period for producing single unit of the particular product or the services of the company which considers two factors for its calculation i.

So, the calculation of eoq economic order quantity formula for holding cost is 2002 1. Markup calculator calculate the markup, formula, examples. Per unit analysis understanding the per unit system and its uses. Source impedance for fault analysis is furnished in per unit. The \ per unit system example example it is known that the internal reactance of a synchronous machine lies typically in the range 1. Formulas for calculating medication dosage basic formula d x q x a where d desired is the dosage the physician ordered, a available is the dosage strength as stated on the medication label, and q quantity is the volume in which the dosage strength is available e. Electrical calculations should be made for all spu projects. Electrical power calculations training jim phillips, p.

Jun 24, 2019 per unit systems is an important concept in power system analysis. Given the system single line diagram, construct and simplify the per unit impedance diagram. It would be very difficult to continually have to refer impedances to the different sides of the transformers thi bl i id d b li i f ll energy systems research laboratory, fiu this problem is avoided by a normalization of all variables. This information is then compared to budgeted or standard cost information to see if the organization is producing goods in a costeffective manner the cost per unit is derived from the variable costs and fixed costs incurred by a production process, divided by the number of units produced. Now that we have both per unit impedances lets fill in the remaining values in our per unit impedance diagram. Power system analysisper unit reactance diagram duration. The per unit system is a method of expressing quantities in an electrical system e. To obtain the new normalized per unit impedances, first we need to figure out.

Per unit and primarysecondary calculations per unit basics a per unit value is the actual value of some quantity divided by the base value of that quantity. In the fault calculation the impedances in the fault circuit must include all significant components and all of these must have their impedance expressed in per unit terms using the appropriate base value. Roi formula, calculation, and examples of return on investment. Transformers can be replaced by their equivalent series impedances. Then a person who is 40 years old is half of the base unit.

When values are expressed in pu, the comparison of electrical quantities with their normal values is straightforward. Per unit pu systems are used by engineers to quantify equipment parameters in terms of their nameplate ratings. We want to determine the prospective fault current at the main switchboard and. In key factor analysis, the contribution per unit is first calculated for each product, then a contribution per unit of scarce resource is calculated by working out how much of the scarce resource each unit requires in its production.

This is the result when the expenses incurred by the entity is equal to the sales. In this video, part 1b, we will be discussing the formulas for converting values into their per unit equivalents and we will also have a look at the term base values. For example, a motor with a 100 horsepower hp nameplate rating which delivers 90 hp to a dynamic load is said to be 90% loaded or 0. May 26, 2019 the reason the per unit system is employed is because it simplifies calculation of currents. Motor steps per revolution 200 step per revolution 1. The cost per unit is commonly derived when a company produces a large number of identical products. Determine the voltage base for all other areas in the circuit by adjusting by the turns. A singlephase 20kva, 480120 v, 60 hz transformer has an equivalent leakage impedance referred to 120volt winding of using the transformer rating as base values, find perunit leakage impedance.

Its also common for management to calculate the contribution margin on a per unit basis. Per unit calculation per unit system examples electrical academia. The per unit system allows engineers to analyze a single phase network where. Elec0014 introduction to power and energy systems the \ per unit system. This formula shows how much each unit sold contributes to fixed costs after variable costs have been paid. Pick a voltage base for each different voltage level, vb. Defect per unit dpu refers to the average number of defects in a given sample product. Again, notice that both transformer per unit impedances are reactive terms and we had to add the j multiplier. May 24, 20 shaft revs per unit 1tooth pitch ns motor revs per unit shaft revs per unit nsnm. Calculate the throughput per unit for each product. Singlephase per unit system advantages of the per unit system. Jan 18, 2017 the per unit system part 03 three problems in per unit quantities problem 01 a 10mva 33kv 3phase generator has a subtransient reactance of 15%. Return on investment roi is a financial ratio used to calculate the benefit an investor will receive in relation to their investment cost. The determination of per unit values is not the end objective of a study.

Property is located in a femadesignated floodplain zone ae and is subject to a 100year. Selecting the generator rating as the base quantities in the generator circuit determine the bus quantities in. Per unit system explaination with solved example electrical. Earnings per share formula examples, how to calculate eps. The easy way to do hand calculation is the mva method. This can be computed by dividing the total cost by the total output. By removing the impact of varying voltages, the necessary calculations are simplified. Equipment impedances can be easily estimated since their per unit impedances lie within a relatively narrow range.

Markup calculator used in managerial or cost accounting, markup formula is the difference between the selling price and cost divided by cost. Introduction to per unit calculations pages 1 11 text. Contribution margin ratio formula per unit example. This ratio is known as the price to earnings ratio or pe ratio. By definition, the per unit value of a quantity is the ratio of the original quantity to its base value which results in a dimensionless per unit or pu value. The per unit system of calculation is a method whereby system impedances and quantities are normalized across different voltage levels to a common base. Calculate all per phase circuit values in per unit with respect to the new bases. The generators perunit voltage is the transmission lines perunit impedance is the other base quantities are 10 0 41. Absorption costing formula calculation of absorption costing. Introduction to per unit systems in power systems part 1b duration. Design calculations establish minimum guidelines and requirements for generating electrical calculations on projects.

The generators per unit voltage is the transmission lines per unit impedance is the other base quantities are 10 0 41. Fortunately, short circuit currents are relatively easy to calculate. The building is located in seismic zone iii on a site with medium soil. Fault calculation methods university of new south wales. These hand calculations are very prone to errors due to so many conversion required. Per unit system explaination with solved example free download as powerpoint presentation. Also called the per unit total cost, this refers to the per unit cost incurred in the production. Only those components actually in the system have to be included, each component must have an x and an r value. In the previous video, part 1a, we saw what per unit systems are and where they are used. Convert actual values to per unit note, per unit conversion on affects magnitudes, not the angles. For example, with a 22220kv voltage rating of t1 transformer, the v b a s. This requires changes in some per unit values if they are already expressed for example on the name plate using different base values. These concepts will be stated and utilized in a stepbystep development.

All the fixed and variable costs must be taken into consideration in calculating the average cost. The base power may be the rating of a single piece of. Define four quantities in per unit of their respective base values. Find the per unit impedance on a base offind the per unit impedance on a base of 100 mva and 5 kv. Voltage bases are related by transformer turns ratios. Per unit representation results in a more meaningful and correlated data. For this purpose, an edu is the level of service in gallons per day for an average residential dwelling. The system calculates this value when the lead time flag is set to v. The per unit system was developed to make manual analysis of power systems easier. Per unit and symmetrical components electrical power.

It uses the time basis code from the routing to calculate lead time per unit and the time basis code from the item master as a common factor to multiply all the lead times per units. The per unit system also makes the calculation easier as all the values are taken in the same unit. The per unit and ohmic method are very tedious manual calculation. Per unit analysis can be used to calculate system three phase fault levels and the current distributions. All p and q quantities are three phase voltage magnitudes are represented as a fractional part of their standard or base value all phase angles are represented in the same units as normally used advantages 1. Every time you cross the transformers, the currents and voltages change. Although powersystem analysis is now done by computer, results are often expressed as per unit values on a convenient systemwide base. Shortcircuit current calculations cooper industries. In many respects the method is similar to the use of percentage values. The higher the ratio, the greater the benefit earned. Using a 8kv, 100mva base in the transmission lines, draw the positive and negative sequence per unit diagrams. Also, the perunit impedances of synchronous and induction machines fall within relatively narrow ranges over quite large size ranges.

Per unit system practice problem solved for easy understanding. Per unit system is when we normalize the voltage and current at each location. If we know the power in watts of an appliance and how many seconds it is used we can calculate the number of joules of electrical energy which have been converted to sortie other form. Easy and simple methods for calculating short circuit curr.

Typically this will be related to the rating of a generator, transformer, or transmission line. Per unit notation in per unit notation, the physical quantity isin per unit notation, the physical quantity is expressed as a fraction of the reference vava ue. Calculations are simplified because quantities expressed as perunit do not. Jul 14, 2016 typical per unit values for transformer impedances. Defining base quantities, per unit voltage per unite current and per unit impedance, selecting the appropriate mva and kv base, calculating the base current and impedance, changing bases, per unit problem solving worksheets, per unit calculation examples and problems.

Per unit system allows the system operator to overlook abnormalities in the system easily. Cost per unit definition, examples how to calculate. The basic equation for calculating a perunit value is shown below. Calculate the per unit current and per unit voltage. Equations used for finding base quantities of impedance, current, and power are shown in table 1, where. The format of the control charts is fully customizable.

Lets see an example to understand variable cost per unit better. The first coil has n1 turns and carries a current i1 which gives rise to a magnetic field b1 g. So, the calculation of eoq for ordering cost is 1010. The application of three or four fundamental concepts of circuit analysis will derive the basic nature of short circuit currents. Download cfis free earnings per share formula template to fill in your own numbers and calculate the eps formula on your own. Defects per unit calculator dpu calculation six sigma. The basic equation for calculating a per unit value is shown below. These loads shall be applicable for the design of buildings. In management accounting, absorption costing is a tool which is used to expense all costs which are linked with the manufacturing of any product. In the power systems analysis field of electrical engineering, a perunit system is the expression of system quantities as fractions of a defined base unit quantity. In breakeven point, it is assumed that all the costs have been paid off including. So much so, it shows up in all exams pertaining to power. In per unit notation, the physical quantity isin per unit notation, the physical quantity is expressed as a fraction of the reference vava ue. On the other hand, c is inversely proportional to d, the distance of separation because the smaller the value of d, the smaller the potential difference.