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—Enthalpy and Dry Bulb Economizer Control
Siemens Building Technologies, Inc. 2-5
Enthalpy Economizer Calculations
Enthalpy economizer control uses a subroutine to perform the
enthalpy calculation. The following calculations can be added to a
PPCL program:
• Enthalpy from dry bulb and relative humidity (Btu/lb or kJ/kg)
• Enthalpy from dry bulb and dew point (Btu/lb or kJ/kg)
For implementation of enthalpy and dry bulb economizer control,
contact your Siemens Building Technologies representative.
APOGEE PPCL User’s Manual
2-6 Siemens Building Technologies, Inc.
Peak Demand Limiting (PDL)
Peak Demand Limiting (PDL) helps companies manage their
electrical consumption during periods of peak demand.
• PDL reduces the electrical consumption of a building control
system by shedding loads (turning OFF equipment) when the
electrical demand exceeds a setpoint.
• Loads are restored (equipment is turned ON) when electrical
demand falls below the setpoint. However, the equipment
remains OFF if restoring the load will exceed the setpoint.
Example
PDL is monitoring an electrical meter that supplies power to three air
handling units and some auxiliary equipment. Two of the air handlers
are currently ON while the third air handler is about to be turned ON.
If all three air handlers and the auxiliary equipment are operating at
one time, PDL predicts that electrical demand will exceed the peak
setpoint of 500 kWh.
To keep electrical demand from exceeding the setpoint, PDL shuts
OFF (sheds) the auxiliary loads that are not critical. Once the
building is operating at a level where the electrical demand will stay
within the setpoint, the auxiliary equipment will be restored.
Why Use PDL?
Companies often have a contracted rate with the utility company
based on their expected electrical consumption throughout the year.
The contract often limits electrical use during periods of peak
demand and sets a maximum use over a period of time. If the
company exceeds the contractual demand, the utility company can
impose surcharges or charge higher rates.