User Guide

Command Syntax
Siemens Building Technologies, Inc. 3-81
g4s Start line for the group 4 load definition in the corresponding
PDLDAT commands. This is the last group to shed when
demand exceeds the setpoint.
g4e End line for the group 4 load definition.
sh4 Shedding sequence for group 4.
• Valid values are 0 and 1.
0 = Fixed shedding
1 = Round robin shedding
Use
Maintains a defined level of kilowatt use (or target) for a group of
loads.
NOTE: For a detailed explanation of Peak Demand Limiting
(PDL), see Chapter 2–Control Option Comparisons.
A single PDL command is responsible for the direct control of a
group of PDLDAT commands in a load-handling field panel. The
PDL command control includes:
• Maintaining a target kilowatt (kW) value by shedding and
restoring loads. The target value is passed to the PDL command
through an LAO point value from the PDLDPG command.
• Monitoring the total available kilowatts under its control. The PDL
command determines which of the loads defined in the
associated PDLDAT command is available for peak demand
limiting control. The total kilowatts available to the PDL command
are placed in an LAO point.
• Maintaining the timing as defined in the PDLDAT command for
minon, minoff, and maxoff.
• Defining how each load under PDL control fits into one of four
priority groups. This is accomplished by referring to the line
numbers of the PDLDAT commands.
• Defining and controlling the sequence of shedding and restoring
for each priority group.
— There are two types of shedding and restoring: fixed and
round robin.
— Shedding begins at 90% of the setpoint.
APOGEE PPCL User’s Manual
3-82 Siemens Building Technologies, Inc.
Example
100 PDL(1,TOTKW1,TGT1,100,199,0,200,299,1,
300,399,0,400,499,0)
Notes
• PDL must control 10-20% of the building demand to be effective.
• When points are controlled by the PDL command, they are
placed into PDL priority. Group 1 is shed first, while Group 4 is
shed last.
• With APOGEE firmware, one meter can be defined in each
program.
• With pre-APOGEE firmware, only one meter can be defined in a
field panel.
• The PDL statement fails if more than four shedding groups are
defined.
• Do one of the following if all four shedding groups are not used:
— With Firmware Revision 2.6/2.6.1 and later, no entry is
required for unused groups.
— With Firmware Revision 2.5.2 and earlier, enter the integer 0
for the starting line, ending line, and shedding type for all the
unused groups.
See also
PDLDAT, PDLDPG, PDLMTR, PDLSET