Download Demand Load

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
Constant Current
Load Diversity
Energy Audit Load
Demand Library 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
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 220.14(I)
Load
Connected Load
Receptacle 1
300 x 180VA / 1000 = 54.00
Receptacle 2
100 x 180VA / 1000 = 18.00
Receptacle 3
200 x 180VA / 1000 = 36.00
Total Served
600 x 180VA / 1000 = 108.00
PTW Part 1 Demand Load
Example Project
To demostrate for
Demand Load Studies
The demand factor is calculated based on the first 10kVA @ 100% demand
with the remaining kVA @ 50% per the NEC.
Load
Demand Load
Receptacle 1
10.00 + 0.50 x (54.00-10.00)
Receptacle 2
10.00 + 0.50 x (18.00-10.00)
Receptacle 3
10.00 + 0.50 x (36.00-10.00)
Total Served
10.00 + 0.50 x (108.00-10.00)
Load
Demand Load
Receptacle 1
10.00 + 0.50 x 44.00 = 32.00
Receptacle 2
10.00 + 0.50 x 8.00 = 14.00
Receptacle 3
10.00 + 0.50 x 26.00 = 23.00
Total Served
10.00 + 0.50 x 98.00 = 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
Load
Design Load
Receptacle 1
32.00 x 1.25 = 40.00
Receptacle 2
14.00 x 1.25 = 17.50
Receptacle 3
23.00 x 1.25 = 28.75
Total Served
59.00 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 10kVA @ 100%, Remaining @ 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
A Datablock
Report
Example Project
To demostrate for
Demand Load Studies
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!