Rockwell Automation Energy Management Accelerator Toolkit Quick Start - Manual (Page 359)

Rockwell Automation Publication IASIMP-QS016C-EN-P - October 2014 359
Chapter
12
Demand Control
Introduction
ControlLogix and CompactLogix controllers, with preconfigured demand logic, can be used as demand controllers to
control a maximum of 16 loads, with the objective of maintaining total plant electrical real power demand below a
threshold, defined by the user, during peak demand periods. The power monitor calculates the predicted end-of-interval
demand according to its demand configuration. It also provides real time clock, end of demand interval, and demand period
time remaining data to the controller. The controller converts predicted demand in excess of the setpoint into kWh to shed
based on the time remaining in the demand interval, and then sheds loads based on their priority and availability until the
predicted demand is under the setpoint. Loads are restored when the predicted demand is less than the demand setpoint by
a hysteresis value.
Alarms are raised if the total sheddable kWh is less than the kWh to shed to satisfy the setpoint, when there is only one
sheddable load remaining, or when a shed command fails to shed the load based on its status input. Alarms are also used to
prompt an operator to remove load override status.
Before You Begin
• Complete an energy assessment and review monitoring methods in Chapter 1 .
• Complete other Energy Monitoring and Analysis chapters as applicable, Chapter 2 through 9 .
What You Need
• Energy Management Accelerator Toolkit, publication IASIMP-SP014 or visit the Integrated Architecture Tools and
Resources website at http://www.ab.com/go/iatools
• RSLogix 5000 software, version 18.0 or later or Studio 5000 Logix Designer application, version 21.00 or later
• FactoryTalk View Machine Edition Software, version 5.1 or later
• Logix controller and supporting hardware
• PowerMonitor 1000 or 5000 unit