Jul 04, 2015 this video discusses basics of per unit quantities and is the first in a series of videos on the subject. Units of measurement physics class 11 download in pdf measurement of physical quantities. Physical quantities and units university of florida. Computation of power system components in per unit aim. Physics is a quantitative science, based on measurement of physical quantities. 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. Transformers, and per unit system spyros chatzivasileiadis. If youve bid a higher price for special quantities, youll get paid at that price per cubic yard. Eng224 lecture 10 per unit system per unit quantities. Things in which quantity is measured are known as units. The number of individual units of a given sku number that are required to make up a larger unit. The bills also provide a measure of the extent of work and this allows the work to be priced. Board footage in standard units of lumber various lengths.
Most excavation contracts have a clause that covers extra work. The unit cost for c is 7% lower under abc when compared to traditional costing. Download as ppt, pdf, txt or read online from scribd. The normalization typically follows transformer ratings. Per unit example how to, tips, tricks, and what to watch out for. The history of the metre and the kilogram, two of the fundamental units on which the system is based, goes back to the french revolution. Or, it may be used on a bill of lading or packing slip to. Singlephase per unit system advantages of the per unit system. Like meals, bulk water planning is calculated on a per person, per day cycle. Per unit fault calculations is a method whereby system impedances and quantities are normalised across different voltage levels to a common base. Rather determined per unit values serve to assist in the calculation of other system values. Unit method of estimating advantages and disadvantages. Any quantity is converted into per unit quantity by dividing the numeral value by the chosen base value of the same dimension.
Also, machine and transformer impedances fall within fairly narrow ranges for each type and construction of device while the per unit system is employed. Jul 05, 2015 this video is the second in a series of videos by on the subject of per unit quantities. Logistics forecasting estimates brigade combat team. Intensity or radiance is defined as radiant energy in a given direction per unit time per. All equipment, quantities and technical data indicated in this schedule are for the contractors guidance only, these are based on the documents prepared by the bhel.
To write a matlab program, to determine the per unit quantities for the. Per unit values for any system is obtained by choosing a set of some base or reference value which can be chosen arbitrarily. This term may be used in production to list the quantity of a specific item that is required to create a complete set or assembled finished product quantity per assembly. The absorbed dose reflects the energy deposited per unit mass, not the total energy.
Cema cema is the acronym for converted energy per unit mass. Pick a voltage base for each different voltage level. Equipment impedances can be easily estimated since their per unit impedances lie within a relatively narrow range. The unit for plane angle is rad and the unit for the solid. Another approach to solve circuits containing transformers is the per unit system. Certain physical quantities have been chosen as fundamental or base quantities. Impedance and voltagelevel conversions are avoided. This article, part of a series of articles, will explain step by step how to calculate these parameters for any component anywhere in the power system. The units defined for the supplementary quantities namely plane angle and solid angle are called the supplementary units.
May 26, 2019 fundamental to any power system analysis is the knowhow of per unit systems. Chapter 12 quantities, costs, and specifications 12. Keeping these two quantities separate protects you. These become useful when performing calculations across a power system where multiple voltage. Quantity of class i liquids in use per laboratory unit.
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. 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. The per unit system is a method of expressing quantities in an electrical system e. Per unit system definition per unit representation of. The quantities e and h are the electric and magnetic. The work included in the item is defined in detail by the rules in the method of measurement. The quantity of excavation to be paid for is measured as outlined in section 209. A further advantage of expressing quantities in per unit theory, shortcircuit calculations, and powersystem sta is that measurements or calculations made on. It is a nonstochastic quantity applicable to directly ionizing radiations such as electrons and protons.
In a per unit system each system variable or quantity is normalized with respect to its own base value. Per unit system allows the system operator to overlook abnormalities in the system easily. In the power systems analysis field of electrical engineering, a per unit system is the expression of system quantities as fractions of a defined base unit quantity. During the prefeasibility stage the consultant setup a preliminary unit cost data base and carried out the cost estimates for. Per unit identities university of minnesota duluth. An asterisk indicates that additional information and suggested formulas to be used in quantity calculations follow the table. Estimating excavation revised craftsman book company. Calculations are simplified because quantities expressed as perunit do not.
Per unit systems is an important concept in power system analysis. Per unit pu quantities the numerical per unit value of any quantity is defined as the ratio of its actual value to another arbitrarily chosen value of quantity of the same dimensions, assumed as the base or reference. Transformers can be replaced by their equivalent series impedances. The definition of an enclosed area differs somewhat. By removing the impact of varying voltages, the necessary calculations are simplified. Per unit analysis for single and three phase systems udemy. Singlephase per unit system university of texas at. Calculations are simplified because quantities expressed as per unit do not change when they are referred from one side of a transformer to t. Units of derived quantities are called derived units. A 50 kg person absorbing the same energy has an absorbed dose of 2 gy 200 rads. Fundamental to any power system analysis is the knowhow of per unit systems.
Using the per unit system and taking into account the transformer percent impedances, solve. Total inventory in use and in storage of class i liquids per 100 ft2 of laboratory area. Planners should use this in their initial analysis for forecasting proper requirements and adjust requirements as the oper. Convert actual values to per unit note, per unit conversion on affects magnitudes, not the angles. The same principle applies to quantities that cannot be expressed in terms of base units, such as number of molecules, which is essentially simply the result of a count. Calculations are simplified because quantities expressed as per unit do not change when they are referred from one side of a transformer to the other. The determination of per unit values is not the end objective of a study. Perunit system for singlephase transfomers the voltages, currents, powers, impedances, and other electrical quantities are measured as fractions of some base level instead of conventional units. Per unit system is when we normalize the voltage and current at each location. View notes eng224 lecture 10 per unit system from eng 224 at charles darwin. Per unit system in electrical engineering electrical. This makes the per unit value of either voltage or current to be around 1. More importantly, while c looks like it is making a loss under traditional costing, abs tells a different story.
Chapter 2 dosimetric principles, quantities and units. Units of measurement physics class 11 download notes in pdf. Dosimetric principles, quantities and units 51 from measurements of stopping powers in heavy charged particle beams, for. A 100 kg person absorbing 100 joules of energy has an absorbed dose of 1 gy 100 rads absorbed dose d and absorbed dose rate d 26 absorbed dose of 1 gy 100 rads. Unit prices shall include any cleaning, material refilling, establishment on site, removal from the site operating plant, canopies, storage of materials, equipment, surplus materials from landfills, machinery, remedy of minor defects, and the site prepared for technical acceptance a. So much so, it shows up in all exams pertaining to power. Define four quantities in per unit of their respective base values. They feed supply to 2 motors of inputs 8 mva and 12 mva respectively.
Atkinson december 2000 nature of bills bills of quantities comprise a list of items of work which are briefly described. Fluence rate has been called particle flux density. For each value, the per unit quantity is the actual value divided by the base value. Here i give you step by step instructions of finding the unknown quantities using the. The coherent derived unit for such a quantity as the ratio of two identical units is the number one. Source impedance for fault analysis is furnished in per unit. Flux and intensity are the two measures of the strength of an electromagnetic field that are central to most problems in atmospheric sciences. Unit labor costs also describe the relationship between compensation per hour worked hourly compensation and real output per hour worked labor productivity.
The per unit value of any quantity is defined as the ratio of actual value in any unit to the base or reference value in the same unit. The labor hours per unit production are determined by dividing the total labor hours of the crew by the daily output. Size length pieces per unit 8 10 12 14 16 18 20 board feet 2x4 1,109 1,387 1,664 1,941 2,219 2,496 2,773. Thus if the mass and volume of a sample of a substance are known, the density is calculated by dividing the mass by the volume, density massvolume or. These quantities are also regarded as being dimensionless, or of.
This video discusses basics of perunit quantities and is the first in a series of videos on the subject. One can also make a physical quantity with a combination of derived quantities. The name for the unit of kerma is the gray gy, where 1 gy 1 jkg. Per unit system is a method used in electrical engineering for the analysis to express the voltage, current, kva and impedance in per unit of base or reference values of these quantity. Physical quantities, measurements standard and units gk physical quantities, measurements standard and units general knowledge general science gs for upsc, ias, banking, railway ssc and other competitive examinations. Per unit system for singlephase transfomers the voltages, currents, powers, impedances, and other electrical quantities are measured as fractions of some base level instead of conventional units. Or in the other words, per unit is a scaling system to make calculation process in analyzing an electrical network system easier, b. The unit method of estimating is the simplest and quickest method of estimating the cost of a proposed construction project.
The unit labor cost indexes are computed by dividing an index of nominal industry labor compensation by an index of real industry output. Per unit system definition it is usual to express voltage, current, voltamperes and impedance of an electrical circuit in per unit or percentage of base or reference values of these quantities. Chapter 2 dosimetric principles, quantities and units j. Chapter 5 quantities calculations 5 2 apr 2007 rev sept 2015 estimated quantities for the more common bridge associated bid items shall be based on the units and accuracy shown in the following table. Usually, the per unit quantities being of the order of unity or less can easily. Panel length panel 36 width 48 60 144 36 48 60 2 33 44 55 60 15 20 25 72 18 24 30 84 21 28 35 96 24 32 40 108 27 36 45 120 30 40 50 1 to convert to board footage. Unanticipated rock deposits, special soil problems and unusual trenching problems are extra work that you should be paid extra for. Figure 3 on page 31 highlights planning factors for this method that are based on the climate. Thus a perunit quantity is a normalized quantity with respect. Per unit calculation per unit system examples electrical. Besides being taught in higher education, it is quite commonly used by engineers in the power industry.
Many quantities are defined in terms of other quantities. The per unit system overview page 1 of 6 overview the per unit system is based on the formula shown in equation 1. Size length pieces per unit 8 10 12 14 16 18 20 board feet. Activity based costing questions and answers prepared by. Payment for such excavation is generally at the unit contract price per cubic yard.
The computation effort in power system is very much reduced with thee use of per unit quantities. This schedule must be read in conjunction with these documents. Per unit system explaination with solved example electrical. In this method, the quantity surveyor counts the number of units which a. Per unit pu systems are used by engineers to quantify equipment parameters in terms of their nameplate ratings. Vin per unit vin kvv base in kv where the base value is a reference value for magnitude. The per unit impedance referred to either side of a three phase transformer is the same regardless of the connection whether they are, yy or. Oct 28, 2017 physical quantities, measurements standard and units gk physical quantities, measurements standard and units general knowledge general science gs for upsc, ias, banking, railway ssc and other competitive examinations. In the power systems analysis field of electrical engineering, a perunit system is the expression of system quantities as fractions of a defined. In this method, the quantity surveyor counts the number of units which are going to be accommodated in a building, for example the number of occupants or main furniture objects used by an individual. Per unit quantities example consider a single phase generating unit rated 50,000 kva at 11,000 volts having an inductive reactance of 0.
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