User Guide
Table Of Contents
- Table of Contents
- How to Use This Manual
- Chapter 1–Program Methodology
- Overview
- Introduction to PPCL
- PPCL Rules
- PPCL Program Design Guidelines
- Relational Operators
- Logical Operators
- Arithmetic Operators
- Arithmetic Functions
- Special Functions
- Order of Precedence
- Resident Points
- Local Variables
- Point Priority Overview
- At (@) Priority Status Indicators
- Point Status Indicators
- Converting a Sequence of Operation intoProgram Code
- Chapter 2–Control OptionComparisons
- Chapter 3–Command Syntax
- Overview
- ACT (Activate lines)
- ADAPTM (Adaptive control, multiple)
- ADAPTS (Adaptive control, single)
- ALARM (Alarm state)
- AUTO (Auto status)
- DAY (Day mode)
- DBSWIT (Dead band switch)
- DC (Duty cycle)
- DCR (Duty cycle routine)
- DEACT (Deactivate lines)
- DEFINE (Define abbreviation)
- DISABL (Disable lines)
- DISALM (Disable alarm)
- DISCOV (Disable COV)
- DPHONE (Disable phone)
- EMAUTO (Emergency, Auto status)
- EMFAST (Emergency, Fast status)
- EMOFF (Emergency, Off status)
- EMON (Emergency, On status)
- EMSET (Emergency, set value)
- EMSLOW (Emergency, Slow status)
- ENABLE (Enable lines)
- ENALM (Enable alarm)
- ENCOV (Enable COV)
- EPHONE (Enable phone)
- FAST (Fast status)
- GOSUB (Go to subroutine)
- GOTO (Go to line)
- HLIMIT (High limit)
- HOLIDA (Holiday)
- IF/THEN and IF/THEN/ELSE (Conditional control)
- INITTO (Initialize totalized value)
- LLIMIT (Low limit)
- LOCAL (Local variable)
- LOOP (Loop control)
- MAX (Maximum value)
- MIN (Minimum value)
- NIGHT (Night mode)
- NORMAL (Normal operating mode)
- OFF (Off status)
- OIP (Operator interface program)
- ON (On status)
- ONPWRT (On after power return)
- PDL (Peak demand limiting)
- PDLDAT (PDL, define load attributes)
- PDLDPG (PDL, digital point group)
- PDLMTR (PDL, meter monitor)
- PDLSET (PDL, setpoints)
- RELEAS (Release)
- RETURN (Return/end subroutine)
- SAMPLE (Sample a statement)
- SET (Set point value)
- SLOW (Slow status)
- SSTO (Start/stop time optimization)
- SSTOCO (SSTO coefficients)
- STATE (State text command)
- TABLE (Table of coordinates)
- TIMAVG (Average over time)
- TOD (Time of day, digital points)
- TODMOD (TOD modes)
- TODSET (Time of day, analog points)
- WAIT (Wait time)
- Overview
- Glossary
- Appendix A—PPCL Reserved WordList
- Index
Control Option Comparisons—Peak Demand Limiting (PDL)
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Why Use PDL Instead of Duty Cycling?
Although duty cycling (DC) can also be used to reduce electrical
demand, duty cycling only controls loads according to a time
schedule. The PDL function can monitor the total electrical demand
and prevent the system from exceeding a demand setpoint.
PDL Application Programs
There are two types of PDL application programs:
• Target Peak Demand Limiting (TPDL)
• Distributed Peak Demand Limiting
These applications are described in more detail in the following
paragraphs.
Target Peak Demand Limiting (TPDL)
With Target PDL (TPDL), the Insight workstation monitors meter
readings, forecasts the demand, and assigns shed targets to each
field panel. The shed target is based on the percentage of total loads
that can be shed by the field panel.
Each field panel is responsible for shedding and restoring the loads
defined in it. If network communication is lost, the field panel
continues to limit demand according to its last assigned target.
Defining Target PDL
TPDL uses two PPCL commands that are defined in the load-
handling field panel. The commands must be defined in the following
order:
1. PDL – Maintains the target kilowatt consumption level by
shedding and restoring loads as needed.
2. PDLDAT – Defines the power consumption limit that is used by
the PDL command.
APOGEE PPCL User’s Manual
2-8 Siemens Building Technologies, Inc.
Distributed Peak Demand Limiting
With Distributed PDL, a field panel on the network monitors meter
readings, forecasts the demand, and assigns shed targets to the
other field panels on the network.
NOTE: Distributed PDL can only work on Protocol 2 networks.
The Predictor Panel
PPCL statements are entered in a specified field panel (called the
predictor panel) to control all meter monitoring and demand
forecasts for a meter area. All meter inputs from the field must be
connected directly to the predictor panel.
The predictor panel compares predicted demand to the demand limit
setpoint and decides how many kilowatts of load must be shed for
the meter area. In addition to monitoring and predicting demand, the
predictor panel is also responsible for keeping data for the reports.
Each predictor panel can control a total of seven load-handling field
panels.
The Load-Handling Field Panels
Each load-handling field panel receives a demand target from the
predictor panel.
The load-handling field panel maintains the demand target level by
shedding and restoring the loads that it controls.