Fluke 7350 specifications Control Band

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RUSKA 7350

Users Manual

Control Band

There are two common pressure control approaches that are available with the

RUSKA 7350 Calibrator. One of the most common control styles is an Active controller where the controller remains operative and holds the pressure at a commanded set-point. This allows the system to hold the pressure at a set-point within the control stability specification (See Appendix A). In addition to possible leaks in a system, following a pressure step, the pressure in the system changes due to temperature effects. When operating an Active control system, the controller continuously monitors any pressure variances in the system and compensates for these effects to hold the pressure at the set-point. The benefit of the Active control is that it can maintain the pressure at the commanded set-point even when there are slight leaks in the system or the system is not thermally stable.

The second approach is to control the pressure in the system to a set-point and then to shut-off the Active controller. We describe this as a Passive control mode. Following a pressure step and the controller becomes passive, the pressure will continue to change in the system due to thermal effects. However these thermal effects will stabilize over time. Once the system has thermally stabilized, pressure measurements can be made in the system without any “pressure noise” injected into the system as a result of having an Active controller in the system. The result would be that the controller would not add any additional uncertainty to the pressure measurement since it would be inactive during the measurement process. For this method, pressure will not be at a cardinal set-point.

When the Control Off Band and Control On Band are set to zero, the Calibrator operates in the Active control mode. Setting a Control On and Off Band, places the Calibrator in the Passive control mode.

The Control On and Off Band provides a tolerance around the pressure set-point in the current unit of measurement. The Controller will control the pressure to the commanded set-point. Once the actual pressure is within the user defined +/- Control Off Band tolerance, the controller will shut off. The pressure will remain at this level, only changing by the thermal influences or leaks in the system. The controller will remain off until it reaches the +/- Control On Band limit. The controller will then re-activate and control the pressure back to the Control Off Band tolerance. This mode of operation removes any added uncertainty in the measurement system due to the controller since the controller is Passive during the high accuracy pressure measurements.

As an example, if a 100 psi (690 kPa) full scale Calibrator was set-up with the Control Off Band at 0.001 psi (0.007 kPa) and the Control On Band set to 0.005 psi (0.035 kPa). This would place the Calibrator in a Passive control mode. If the Calibrator was placed into the control mode with a pressure set-point of 10 psi (69 kPa), it would control up to the 10 psi (69 kPa) value. Once it reached a pressure of 9.999 psi (68.993 kPa) the active control would turn off. Due to the thermal effects caused by pressurizing the system, the pressure will start reducing in the system. Once the pressure reaches 9.995 psi

(68.965 kPa) the active controller would automatically turn on and control the pressure back to 9.999 psi (68.993 kPa) and then turn off. After a few cycles, the system will thermally stabilize and the pressure will hold between the Control On and Control Off Bands.

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Contents Ruska Limited Warranty and Limitation of Liability Table of Contents Theory of Operation Remote Operation Preparation for Storage and Shipment List of Tables Ruska List of Figures Viii Introduction How to Contact FlukeGeneral Information General InformationSafety Information Symbols Used in this Manual FeaturesEase of Operation Power-On Self TestAutomatic Zero Adjust Easily ProgrammableStandard Equipment & Options Ruska 7350 Options List Part NumberRuska Electronics Section Power SupplyTheory of Operation Back Plane BoardRuska 7350 Block Diagram Front Panel IEEE-488 InterfaceMotor Controller Pneumatic Pump Pneumatic Module76xx Interface Board GearmotorSystem Transducer Electronics RegulatorDome Regulator Test PortRuska Installation Unpacking the RuskaPneumatic Connections Powering Up the RuskaDrive Air Supply Port Numeric Keypad Local OperationLocal Operation Function KeysCancel, Previous Menu TreeTutorial Main MenuMain Menu Entering Pressure Tare Mode Selecting Mode of OperationSelecting Language Controlling Pressure Setting the Pressure Set-PointMain Menu Triple Range OptionalVent Step/JogMenu Setup MenuLow Limit Menu Setup LimitsHigh Limit Auto VentControl Band Slew Rate AccessMenu Setup User Slew LimitReady Tolerance Step SizeBar Graph Maximum Gas Head Pressure CorrectionChanging the Number of Decimals Menu Setup UnitsPressure Filter Key Click13. Menu Setup Units Edit Name Menu Gpib Address Menu Setup RemoteMenu Setup System ProtocolDate/Time ResetCalibration Password Menu CalibrateMenu Program Storing a Sequence in Memory Preparing to ProgramMaxTime Mode of EntryEntering a New Program 17. Menu Program Edit Menu Automatically Generating a Program 18. Menu Program Edit Auto MenuChanging the Name of a Program Changing an Existing ProgramChanging the Configuration Stored with a Program 20. Menu Program Edit Menu21. Menu Program Config Menu Running a ProgramMenu Test Menu Test Sweep TestMenu Test Self Test Menu Test Remote TestMenu Test Shop1 26. Menu Test Shop1 MenuMenu Display Menu Display BlankRuska Capabilities Remote OperationRemote Operation IEEE-488Remote/Local Operation RS-232Device Messages ConfigurationScpi Command Format Scpi Response FormatANSI/IEEE 488.2-1987 Command Summary Scpi Command SummaryMODE? Example Scpi Commands ListScpi Status Registers Interface Panel Emulation Serial Operation Ruska Observing the Ruska 7350’s Full Scale Rating MaintenancePreventive Maintenance Observing the Software Version NumberProcessor Battery CalibrationCalibration Instructions Single Sensor PreparationStoring the Coefficients Editing the Calibration Coefficients ZeroingRuska 7350 Pump Lubrication CleaningFuse Disconnection Instructions Preparation for Storage and ShipmentPacking Instructions Fluke Calibration Westpark Drive HOUSTON, TX USA Shipping Instructions Packing the Calibrator7350 Summary of Specifications AccuracySpecifications Summary of Specifications Ruska Summary of Error Messages Summary of Error MessagesSetpoint is out of range