PCC-III Loop Controller

Overview

The fully configurable PCC-III Controller is a complete solution for boiler control and a variety of process control applications. The PCC-III is a Multiple Loop Controller with highly developed "Blockware" based control strategies and a large selection of standard and optional I/O quantity. Unique operational and commissioning features make the PCC-III the right selection for the most demanding applications.

• User-Friendly
• Helpful Commissioning Tools
• Uncomplicated Configuration
• Low Installed Cost
• Expandable I/O
• Application Expertise
• Unique Features

User-Friendly

• Easy to Read Displays - Large numeric and English language displays, pushbuttons & intuitive bargraphs provide clear process information.
• Ten (10) Process Displays - A flexible process variable display allows the operator to view up to 10 process variables each with an up to 16 character English language description message.
• Ten (10) Point Annunciator - The "first-in-first-out" annunciator allows the operator to view the order of alarms and acknowledge each separately.
• Configurable "Lights and Buttons" - Configurable "lights and buttons" allows incorporation of auxiliary functions in the controller without the addition of external hardware.
• Industry Standard Communications - Built-in industry standard communications allows the controller to be remotely monitored or controlled by other hardware/software which communicate via "Modbus" protocol

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Helpful Commissioning Tools

• Front Panel Configurable - Intuitive "Blockware" changes may be made directly on the Controller front panel and is menu driven with English Language display prompts. No additional configurator or laptop computer is required. Optionally, a portable computer may be connected to the controller for up and downloading configuration data through a object oriented graphical interface.
• Automated Boiler Fine-tuning - The PCC-III Controller provides a simple "Learn" function that allows the points on the various curves to be set by manually setting the control outputs to the desired operating points and pressing a single button. All the relevant curve points for that particular firing rate are stored in the controllers memory without any need to take data, perform calculations, or refer to a logic diagram.
• Built-in Edit Menus - The PCC-III's "Quick Menu" feature allows rapid editing of tuning constants, alarm setpoints, and key parameters. The "Last Parameter" feature allows "one step" return to the last edited parameter.
• Password Protection - Once boiler fine-tuning is completed the commissioning data can be password protected for configuration security.
• Redundant Memory Operations - The PCC-III Controller redundant nonvolatile memories to protect configuration data, tuning parameters and operating status information. Data may be copies between primary and removable backup memories. The backup memory may be used to copy configuration from one boiler to the next without the need for the optional laptop and configuration software.
• Unmatched Diagnostic Tools - The PCC-III includes "Examine", "Block Force" and, "Service Manual" Troubleshooting Modes to allow rapid, efficient control system evaluation

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Uncomplicated Configuration

• Intuitive, easy to configure "soft wired" blockware
• Flexible configuration methods - The PCC-III Controller offers built-in front panel edit menus with English display prompts or the spreadsheet style PC3-Edit™ or fully featured PC3-Draw™ object-oriented CAD configuration tools.
• Expandable - Up to 160 blocks and 60 different function types
• Quick, Simple Up/downloads via PC or Laptops

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Low Installed Cost

• Existing Burner Panel Mounting - The PCC-III has a small 7 ¾" deep case with weather/rainproof construction.
• Large integral I/O capacity - A single PCC-III is capable of dual fuel, fully metered control with oxygen trim.
• Integral oxygen sensor - The PCC-III has a "Z" Option Card that eliminates the need for external oxygen transmitter.
• Direct BMS interfacing - Each PCC-III includes standard 120 Vac inputs and 8 Amp relay outputs eliminate need for interposing relays.
• Direct electric actuators interface - The PCC-III has triac output option cards that eliminate the need for costly local positioners.
• Power Supply - The PCC-III has a built-in surge suppressor, 99-135 Vac input power rating and an internal transmitter power supply - 215 ma 24 Vdc that eliminate the need for external components.
• True Multiple Loops Controller - Multiple loop control capability allows cost effective control of more than one process loop in a single controller
• Free project proven combustion solutions - Refer to the "PCC-III Control Standard Configurations" for a list of some available control strategies

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Expandable I/O

• Base Unit includes 5 Analog Inputs, 2 Analog Outputs, 5 Discrete Inputs and 6 Discrete Outputs
• Up to 15 Analog Inputs, 4-20mAdc
• Up to 6 Analog Outputs, 4-20mAdc
• Up to 13 Discrete Inputs, 120 Vac
• Up to 6 Relay Outputs, 8 A Inductive
• Up to 7 Triac (Pairs) Outputs, 2 A
• Up to 2 Direct Connected ZP Oxygen Sensors (Connected without external oxygen transmitter)
• Up to 31 Total Input-Output

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Application Expertise

• Preferred has a large library of pre-configured boiler control strategies that are available at no extra cost.

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Unique Features

• Integral ZP Oxygen Sensor
• "Learn Mode " function
• Built-in boiler efficiency calculation block using the ASME losses method
• Direct electric actuators interface using internal Triac outputs
• Direct BMS interfacing with internal 120 Vac inputs, 8 Amp relay outputs
• "Examine", "Block Force" and, "Service Manual" troubleshooting modes

Benefits

Safe Boiler Operation

• Accurate, Repeatable Combustion Control - Fuel and air flows are matched in order to maintain proper fuel to air ratio at all times, too little air causes unburned fuel losses, too much air causes excessive stack losses and improper fuel air ratio can be DANGEROUS. Any combustion project requires the assessment of existing piping, burner and boiler conditions, process measurements, analyzers, linkages, actuators, control valves control dampers and operational requirements. Preferred's focus on combustion applications, with over 1100 boiler control systems installed, brings the required experience to the evaluation, development and commissioning of each project.
• Redundant non-volatile Memories and Service Manual Mode - The PCC-III Controller is capable of "self recovery" in the event of a severe 120 Vac electrical power disturbance or some other phenomenon that alters data in memory or otherwise confuses the microprocessor.
• Optically Isolated RS-485 Data Highway - The PCC-III Controller includes optically isolated communication to prevent a single controller failure from disrupting an entire network.
• Boiler Control Experience - Extensive boiler control experience is the key to safe and reliable boiler control. Preferred's focus on combustion applications, with over 1100 boiler control systems installed, brings the required experience to the evaluation, development and commissioning of each project.

Decreased Flue Gas Emissions

• Ideal (stoichiometric) Combustion - Ideal combustion assumes all fuel comes into contact with all oxygen. Practical, real world limitations require extra air to assure that this happens. Too much excess air will cause good combustion but low efficiency and increased NOx.
• Various emissions are to be avoided - Particulate (opacity) and carbon monoxide are caused from insufficient combustion of the carbon. NOx emissions are caused by oxidation of the nitrogen in the fuel and air.
• Ways to reduce emissions - Better mixing of the fuel and air to reduce opacity and carbon monoxide while staged combustion and flue gas recirculation are often used to reduce NOx.
• Low Excess Air - Low excess air operation reduces both thermal and fuel NOx by reducing the O2 available for combustion.

Decreased Fuel & Electrical Energy Operating Cost

• Combustion requires time, temperature, and turbulence - Enough time for the reaction to occur, sufficient temperature to ignite the fuel and start the process, and turbulence to assure mixing of fuel and oxygen. We introduce extra air to assure that this happens. Too much excess air will cause good combustion but low efficiency, as you will be heating this air rather than the water in the boiler.
• Maintain Optimum Performance - As combustion conditions change it becomes necessary to tune or recalibrate the fuel air ratio and oxygen setpoints. The PCC-III Controller provides a simple “Learn” function that allows the points on the various curves to be set by manually setting the control outputs to the desired operating points and pressing a single button. All the relevant curve points for that particular firing rate are stored in the controllers memory without any need to take data, perform calculations, or refer to a logic diagram.
• Oxygen Trim – Flue gas oxygen is measured and compared against setpoint to continuously adjust (trim) the air / fuel ratio. Oxygen trim saves fuel by fine tuning the burner to operate safely and reliably at reduced excess air levels throughout the burner firing range.
• Variable Speed Fan Combustion Air Flow Control – Combustion air flow is matched to fuel flow by adjusting fan speed rather than adding increasing pressure drop with across the air damper. By incorporating a variable speed drive the damper pressure drop is minimized, and kWh usage is decreased.
• Real Time Boiler Efficiency Calculations - The efficiency of a burner-boiler combination is simply the amount of useful energy leaving the system expressed as a percentage of the chemical energy in the fuel entering the system. Real-time boiler efficiency information enables the operator to instantly identify inefficiencies and potential operational problems. The PCC-III Controller’s built-in function block calculates boiler efficiency using the ASME “by-losses” method.

Applications

PCC-III Multiple Loop Controller example applications

Boiler Monitoring

• Flue Gas Oxygen Monitoring with ASME “By Losses” Efficiency Calculation for One (1) or Two (2) Boilers
• Data Acquisition with up to 15 Analog Inputs or 13 Digital Inputs

Header Temperature or Pressure Control

• Two (2) or Three (3) Boiler Modulating Lead/Lag Control
• Plant Master Modulating Control

Single Point Positioning Combustion Control

• Firing Rate Control
• Firing Rate Control with Oxygen Trim Control using Link Trim Actuator (LTA) or Fuel Trim Output
• Firing Rate Control with Draft or Drum Level Control

Parallel Positioning Combustion Control

• Firing Rate Control
• Firing Rate Control with Oxygen Trim Control
• Firing Rate Control with Oxygen Trim Control and Variable Speed Drive (VSD) Combustion Air Fan Control

Fully Metered Combustion Control

• Firing Rate Control
• Firing Rate Control with Oxygen Trim Control
• Firing Rate Control with Oxygen Trim Control and Variable Speed Drive (VSD) Combustion Air Fan Control

Integration

The PCC-III Controller has an optically isolated RS-485 communication ports that uses industry standard Modbus protocol. This built in integration infrastructure allows the unit to be easily integrated into a data acquisition and distributed control system with the safety and reliability of an optically isolated system.

PCC-III's have a "virtual presence" in Preferred's SCADA/FLEX distributed control system. Customized graphics allow the user to see and control and tune the PCC-III as if they were standing in front of the unit.

Configuration

Programming configurations is a challenging task for most programmable controllers.  The PCC-III multiple loop controller is the exception to this rule with three different ways to create configurations:

• Directly from the faceplate of the controller using the built-in edit buttons
• PC_Edit™
• PC_Draw™

Both PC_Edit™ and PC_Draw™ software allow the user to design Blockware configurations and upload/download them to the PCC-III controller through the PC3-Link™ cable connecting the serial port of your computer to a standard RS232 connection on the PCC-III controller.

PC3_Edit™

• The “point and click” simplicity of the PC3_Edit™ software makes “Blockware configuration simple and intuitive
• It uses straightforward spreadsheet format with a convenient fill-in-the-blanks approach.
• The “Blockware” data and comments can be printed to any MS Windows® compatible printer
• The generated configurations are easily downloaded to the controller through the PC3-Link™ cable

PC3_Draw™

• The powerful object-oriented CAD interface in PWC_Draw makes the program the ideal choice for rapid “Blockware” programming in a visual environment
• The program is built on a Visio® platform
• Functions are simple dragged onto the drawing page and connected with “Smart Connector” lines to interconnect the Blocks
• Block inputs are automatically generated by placing the Block Connections
• Drawings can be printed on any MS Windows® compatible printer or plotter