SKM Power*Tools for Windows Part 1 Demand Load

PTW Part 1 - Demand Load Agenda Review of one-lines and the database The purpose of a Demand Load Study Load Types (definitions) Connected, Demand and Design

PTW Part 1 - Demand Load Agenda (con’t) A Load is: Real Power (kW) absorbs power Reactive Power (kVAR) absorbs or supplies Applicable Types include Non-motor Load, Induction Motor, Synchronous Motor, Resistor, Reactor, Capacitor Bank, Single Tuned Filter and High Pass Filter components

PTW Part 1 - Demand Load Agenda (con’t) Load Type Constant kVA, Constant Impedance or Constant Current Load Diversity Energy Audit Load Demand Library Load A table that represents the Load Factors for different Load Categories LCL (Long/Continuous Load) Factor

PTW Part 1 - Demand Load Agenda (con’t) Demand Load Study Assumptions Single Power Source at a time Radial Network (Loop connections are temporarily opened) Calculated load currents are based on the load bus nominal Voltage Study Solutions Manual PTW

PTW Part 1 - Demand Load Agenda (con’t) Demand Load Study Output Data Reporting Options Traditional reports Crystal reports Datablock reports One line diagrams with datablocks – export drawing to clipboard or print forms

PTW Part 1 - Demand Load The Purpose of a Demand Load Study Is to calculate the Connected, Demand and Design load flowing in branch circuits A Load is a component that absorbs real power (kW) from the distribution system. Applicable load types include Non-motor Load, Induction Motor, Synchronous Motor, Schedule, Resistor, Reactor, Capacitor Bank, Single Tuned Filter and High Pass Filter components. (Reactive power (kVAR) can be absorbed from or supplied to the distribution system.)

PTW Part 1 - Demand Load Connected Load The Connected Load is the value entered as Rated Size in the General Load or the Induction/Synchronous Motor subview of the Component Editor.

PTW Part 1 - Demand Load

PTW Part 1 - Demand Load

PTW Part 1 - Demand Load The Demand Load is calculated by the program through multiplication of the coincidence factor to the connected load. In PTW the coincidence factor is called the Load Factor and is defined by the user. This is done in the Load Diversity subview of the Component Editor. This subview appears differently for each load component.

PTW Part 1 - Demand Load Motor Load

PTW Part 1 - Demand Load Non-Motor Load Energy Audit Load Demand Library Load

PTW Part 1 - Demand Load Demand Load Library ANSI or IEC Accessed through Document, Library, selecting Demand Load Library, and then selecting IEC.dld

PTW Part 1 - Demand Load Design Load Design Loads are normally used as the reference for sizing equipment. LCL (Long/Continuous Load) Factor This Factor is read from the Demand Load Library and represents the long or continuous characteristic of the load as defined in NEC and will be applied to the calculated demand load category. NEC Article 100 defines a Continuous Load as, “a load where the maximum current is expected to continue for 3 hours or more.”

PTW Part 1 - Demand Load Design Load The Design Load is calculated by the program through multiplication of the LCL or Motor Load Design Factor (in Load Study Set up).

PTW Part 1 - Demand Load Demand Load Study Assumptions Single Power Source at a time Radial Network (Loop connections are temporarily opened) Calculated load currents are based on the load bus nominal Voltage

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies Input Data: Source: 208V, 3-Ø, 60Hz, 30.3kA Receptacle Load 1: 300 duplex receptacles Receptacle Load 2: 100 duplex receptacles Receptacle Load 3: 200 duplex receptacles Assume all loads operate at a 0.90 lag pf. and operate continuously over 3 hours per day. All feeders size 12, 4-1/C+G, 600V, CU, THWN, RGS conduit with a length of 100ft

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies Study Solutions Manual PTW

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies Manual Solution: Note: Because the load power factors are equal, the individual Connected Load kVA magnitudes can be summed directly. 1 duplex receptacle = 180VA per NEC Article (I) LoadConnected Load Receptacle 1300 x 180VA / 1000 = Receptacle 2100 x 180VA / 1000 = Receptacle 3200 x 180VA / 1000 = Total Served600 x 180VA / 1000 =

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies The demand factor is calculated based on the first 100% demand with the remaining 50% per the NEC. LoadDemand Load Receptacle x ( ) Receptacle x ( ) Receptacle x ( ) Total Served x ( ) LoadDemand Load Receptacle x = Receptacle x 8.00 = Receptacle x = Total Served x = 59.00

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies Based on assumption that the receptacle loads operate continuously over 3 hours per day the LCL factor is 1.25 for the Design Load calculation LoadDesign Load Receptacle x 1.25 = Receptacle x 1.25 = Receptacle x 1.25 = Total Served59.00 x 1.25 = 73.75

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies PTW Solution: We need to edit the Demand Load Library – Either edit or create the load category - Receptacle, Constant kVA, 1st 100%, 50%, LCL=1.25, pf=0.9 lag

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies In the General Load subview enter the Connected Load in the Rated Size field and the Power Factor info in those fields. In the Load Diversity subview link the component to the Receptacle Demand Library Load category. Do this for eac load.

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies Run a Demand Load Study select Run>Balanced System Studies or click on the short cut Icon

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies Check Demand Load, click on Setup and enter info as below. Then click on Run

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies Confirm study results by running a datablock format for Demand Load. The results are displayed below and match the manual solution results shown in a previous slide.

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies Demand Load Study Output Data Reporting Options One line diagrams with datablocks – export drawing to clipboard or print forms Datablock reports Traditional reports

PTW Part 1 - Demand Load Example Project To demostrate for Demand Load Studies A Datablock Report

PTW Part 1 - Demand Load Let’s go to PTW to take a look at the Demand Load Library (Go through the steps of the Demand Load Problem)

PTW Part 1 - Demand Load Any Questions?

PTW Part 1 - Demand Load Thank You for Attending!