Emerson 20/20 service manual Load Anticipating, Oil Control, Liquid Injection

Page 45

Section 6 • Compressor Control

Load Anticipating

The purpose of the load anticipating algorithm is to re- duce the amount of overshoot of the capacity slide posi- tion while the compressor attempts to meet the control setpoint. This advanced feature of the Vission 20/20 closely monitors the rate of change of the process vari- able and compares it to the control setpoint. If the pro- cess variable is changing in the direction of the control setpoint at the specified rate or greater, then the normal command to move the capacity slide is interrupted. The rate is calculated between time intervals set in the pro- portional control section of this screen.

Enable Load Anticipation Algorithm:

•Allows the operator to choose if the load anticipation algorithm runs.

Rate Dead Band:

•Defines the rate at which the capacity slide move- ment will be interrupted. This value is an absolute val- ue of the process variable. For example, the default value is 0.25. If the control mode is suction pressure, then this value is 0.25 Psig or if process temperature is the control mode then the value would be 0.25°F.

Oil Control

These setpoints determine how the Vission 20/20 will manage the oil of the compressor.

Oil Pump Press Restart Ratio:

•The on and off setpoints define when the oil pump will cycle on and off if the oil pump is selected to cycle from the configuration screen.

Oil Separator Heater Temp:

•When the oil temperature falls below this setpoint the oil heater will turn on. Note, there is a 5°F differen- tial associated with this setpoint. For example, when set at 100°F, the heater will turn on at 95°F and off at 105°F.

Liquid Injection

The setpoints is this section are to control the behavior of the liquid refrigerant injected into the compressor for oil cooling purposes. The liquid injection solenoid con- trol is based off of discharge temperature whether the compressor uses just an injection solenoid or a motor- ized valve in conjunction with the solenoid.

Liquid Injection Solenoid Control ONLY

•When using only the liquid injection solenoid, the so- lenoid is activated once the value of discharge tem- perature meets or exceeds the value of “Liquid inj. Setpoint 1” and the value of oil separator tempera- ture meets or exceeds the value of “Oil Sep. Temp. Override”. The injection solenoid will deactivate if either of setpoints are not met. This will prevent situ- ations where the discharge temperature may rise quickly, but the oil temperature is still very cold. By preventing the liquid injection solenoid from turning on at this point, the oil separator will not be subjected to additional liquid refrigerant, that would cool the oil even further.

Liquid Injection Control using a 4-20ma motorized valve.

•When a motorized valve is used to control the amount of liquid being injected into the compressor the pre- viously mentioned setpoints have a slightly different function. The Oil Sep. Temp. Override is still used in controlling the injection solenoid, however the Liquid Inj. Setpoint 1 is now used as the target temperature for the PID Algorithm that controls the position of the motorized valve. The algorithm compares the actual discharge temperature against the Liquid Inj. Setpoint 1. The difference between these is the error. The PID algorithm tries to drive the error to “zero” by moving the positioning valve to allow more or less liquid refrigerant to be injected into the compressor.

•PID algorithm can be notoriously hard to tune. As a result the Vission 20/20 offers a couple of addi- tional features to help control wild fluctuations in oil temperatures that could result in the compres- sor tripping off. The operator can choose to enable the minimum value position that automatically sets the liquid injection motorized value to the specified value whenever the discharge temperature has fallen below the Liquid inj. Setpoint 1. This feature nearly eliminates the overshoot of the PID in the downward direction and reduces the chance of the compressor tripping off due to low oil temperature. The operator can also choose to use an average of the discharge temperature and the oil manifold temperature as the control variable. The discharge temperature can vary quite drastically forcing the PID algorithm to drasti- cally adjust the motorized value. By averaging the more stable oil manifold temperature and discharge temperature, the control variable stabilizes and the PID is more easily tuned.

•Please note that as stated above, PID algorithms can be difficult to tune and there is no one set of PID val- ues that will work. The work required for a compres- sor to meet the requirement of its installation vary greatly and therefore the amount of heat transfered to the oil varies just as greatly. We recommend the

Vission 20/20 • Operation and Service Manual •Vilter/Emerson • 35391SC 1.8.5153

6 – 7

Page 44 Page 46
Image 45
Page 44 Page 46
Contents Vission 20/20 micro-controller Page Table of Contents Digital I/O Board Layout Top Status Bar TOCCompressor Sequencing Event List Data Backup List of Tables and Figures END of TOC How to Use This Manual Requirements to Start Compressor Operational Flow ChartsCritical Compressor Run Logic at Compressor Start Compressor Amperage Load LimitingOperational Flow Charts 2 Installation Recommendations Proper Wiring SizingVoltage Source DC signals GroundingMixing Voltages Correct Transformer Wiring Method Wiring MethodsBest Practices Overview Hardware ArchitectureDigital Input/Output I/O Board Description Type Digital I/O 1Refer to -2. Analog Inputs Motor Current Analog InputsAnalog Inputs 1 Digital I/O 2Digital & Analog I/O Boards Layout Analog OutputsDigital I/O Board Layout Analog Inputs 2Digital Output Board Layout Digital Output BoardsDigital Input Board Layout Digital Input BoardsDigital Input-Output Board Layout Digital In-Out BoardsAnalog Input Board Layout Analog Input BoardsAnalog Input Jumper Tables Channel SignalJP-13 JP-14 JP-15 JP-31 Analog Output Board Layout Analog Output BoardsMain Screen Main ScreenTop Status Bar Parameter Bar Unit Start Pop-Up Window Bottom Status Bar Splash Screen Navigation Buttons Menu ScreenMenu Screen Pulse Proportional Control Compressor ControlProportional Band & Setpoint Auto-CycleVFD One-Step Control Method Variable Frequency Drive VFDPumpdown Control Pulldown Control Volume Slide Position Offset Control ModeStop Load and Force Unload Capacity Slide Triggered OutputsLoad Anticipating Oil ControlLiquid Injection Compressor Control Alarms and Trips Setpoints Alarms and TripsAlarms and Trips Compressor Inhibits Safety Failure MessagesFalse Start Timer Setpoints TimersOil Separator Level #2 Safety Trip Delay Timers Blank Scheduling Setpoint Compressor SchedulingCompressor Scheduling Pressure Control Setpoints Compressor SequencingCFM Equipment List 10 4 / Blank Condenser Control Setpoint Condenser ControlStep Control Step Control Screen VFD Settings11 4 / Blank Digital Outputs Service OptionsAnalog Outputs Instruments Calibration Pressure and Temperature InputsRemote Capacity Motor CurrentAnalog Inputs 13 4 / Blank Capacity Slide Valve Potentiometer Slide CalibrationVolume Slide Valve Potentiometer Slide Valve OperationSlide Valve Actuator Calibration for Optical Style Motors Photochopper Command Shaft Rotation Required By Actuator Command Shaft RotationSlide Valve Troubleshooting Guide 1 Slide Valve Troubleshooting GuideSlide Valve Troubleshooting Guide 2 LED Blink Codes and Troubleshooting Guide 1 Slide Valve Actuator Troubleshooting Guide Blink CodePleted. The actuator will not move while this error code LED Blink Codes and Troubleshooting Guide 2Chart Operation Trend ChartTrend Data Storage Trend Setup Screen Setup15 4 / Blank Event list Columns Event List16 2 / Blank Input/Output Screen Input / Output17 2 / Blank Digital Inputs Auxiliary Input / OutputDigital Outputs Control 18 4 / Blank Configuration UnitsTime & Date Communications TouchscreenAnti-Recycle Compressor Sequencing Restart On Power FailureLanguage Model & RefrigerantOptional Function Selection Compressor ControlOil Pump Condenser ControlOil Cooling Motor Current DeviceDigital Inputs Analog Inputs Analog Outputs Configuration 19 10 / Blank Save / Load Data BackupData Backup Migrate Factory Reset20 4 / Blank Checklist MaintenanceLog ChartApply User AccessManage Accounts LoginScreen Security Levels Security Access Levels22 4 / Blank Help Screen Screen FeaturesVersion Pop-Up Screen Twin Screw Control Screen Twin Screw ControlOperation Cool Compression Control Screen Cool Compression ControlCool Compression Control Functions Screen Control FunctionsOperational Differences from Single Screw Auto Load TimerCool Compression Control

20/20 specifications

Emerson 20/20 is an advanced platform designed for real-time data analytics, visualization, and operational optimization in industrial settings. This robust solution aims to empower organizations by providing actionable insights derived from their operational data, enabling enhanced decision-making and improved efficiency.

One of the standout features of Emerson 20/20 is its ability to integrate seamlessly with various sources of data, whether structured or unstructured. It consolidates information from different systems, such as historians, control systems, and ERP software, allowing users to gain a comprehensive view of their operations. This integration capability is crucial for businesses looking to maximize their data utilization without being confined to a single data source.

The platform employs powerful analytics tools that utilize machine learning and artificial intelligence technologies. These tools are designed to automatically identify patterns, anomalies, and trends in real-time. By leveraging predictive analytics, Emerson 20/20 helps organizations forecast potential issues before they escalate, allowing for proactive maintenance and minimizing downtime.

Emerson 20/20 also features user-friendly visualization dashboards, which provide customizable views tailored to individual user roles. This means that whether you are a plant manager, a process engineer, or an executive, you can access relevant data that speaks directly to your needs. These dashboards facilitate easier understanding of complex data sets, promoting informed decision-making across the organization.

One notable characteristic of Emerson 20/20 is its adaptability and scalability. Businesses of all sizes can implement the platform and scale its features according to their needs. This flexibility ensures that both small operations and large enterprises can derive value from the solution, making it an attractive option for various industries.

Additionally, the platform is designed with cybersecurity in mind, ensuring that data integrity and confidentiality are maintained. This aspect is increasingly important as industries become more interconnected and target more sophisticated cyber threats.

In summary, Emerson 20/20 stands out as a powerful tool for organizations seeking to harness their operational data effectively. With its advanced analytics capabilities, seamless integration, customizable visualization, and scalable design, it offers a comprehensive solution to optimize industrial performance and support data-driven decision-making. As businesses continue to navigate the complexities of modern operations, Emerson 20/20 provides the insights necessary to stay competitive and responsive to changing market demands.
Top Page Image Contents