User Guide

Table Of Contents
Control Option Comparisons—Peak Demand Limiting (PDL)
Siemens Building Technologies, Inc. 2-9
Defining Distributed PDL
Distributed PDL uses five PPCL commands that must be defined in
the following order:
1. PDLMTR – Monitors consumption meters to determine power
usage, maintains consumption reports, predicts usage, issues
warnings, and restarts meters.
2. PDLSET – Assigns various consumption limiting setpoints to
specific time intervals.
3. PDLDPG – Distributes the difference between the PDL resident
point and the setpoint.
4. PDL – Maintains the target kilowatt consumption level by
shedding and restoring loads as needed.
5. PDLDAT – Defines a power consuming load that will be
controlled by a PDL command.
The predictor field panel must have the PDLMTR, PDLSET,
and PDLDPG commands defined in its PPCL program.
Each load-handling field panel must have the PDL and
PDLDAT statements defined in its PPCL program.
NOTE: This configuration assumes that the predictor field panel
does not have any loads defined. If the predictor field
panel is also controlling loads, the PDL and PDLDAT
commands must also be defined in the PPCL program.
APOGEE PPCL User’s Manual
2-10 Siemens Building Technologies, Inc.
Start/Stop Time Optimization (SSTO)
The Start/Stop Time Optimization (SSTO) feature adjusts the
equipment start and stop based on calculations that optimize use of
the system.
The equipment start and stop times are based on the outside and
inside temperatures of the building. Each time the value of the indoor
or outdoor air temperature changes, SSTO recalculates the optimal
values for system operation.
Where to Use SSTO
SSTO programs should be used in areas with extreme outside
zones, unstable environments, or zones where the space
temperature is affected by elements like wind, sunlight, or auxiliary
sources of heating or cooling loads.
Example
SSTO is controlling the lobby of a building. When the lobby opens at
8:00 A.M.,, the temperature must be 75°F.
If the lobby temperature is 72°F at 7:30 A.M., SSTO calculates that
the system needs 10 minutes to warm the lobby to 75°F by 8:00.
SSTO starts the warm-up procedure for the lobby at 7:50 A.M.
On another day, the lobby temperature is 69°F. SSTO calculates that
the system needs 20 minutes to warm the lobby to 75°F by 8:00
A.M. SSTO starts the warm-up procedure at 7:40 A.M.