Emerson iCOM user manual Motorized Ball Valve in Digital Scroll Units

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Operation

3.2Motorized Ball Valve in Digital Scroll Units

On digital scroll units, discharge pressure is controlled by a motorized ball valve. During unloaded operation, pressure changes during each digital cycle could cause a pressure-controlled water regulat- ing valve to open and close an excessive number of times.

The motorized ball valve is designed to maintain a consistent peak discharge pressure on Water/Gly- col Cooled Digital Compressor Systems.

The control algorithm for the motorized ball valve uses an intelligent sampling rate and adjustable pressure thresholds to reduce the number of times the valve opens and closes. The valve assembly consists of the brass valve, linkage and actuator.

Each compressor has one motorized ball valve that is driven by the analog output of the Liebert iCOM control board based on pressure. If there is a call for cooling, the compressor start is delayed by a 30- second timer. During this delay, the motorized ball valve is set to 50% open. The compressor will start after the 30-second timer elapses.

Motorized Ball Valve Manual Mode: (Service/Service) Manual operation can be selected to allow service personnel to control the motorized ball valve from the Liebert iCOM control only when the system is in manual mode.

When Auto BV Control is selected, the motorized ball valve functions as it would be during normal system operation.

NOTE

Compressor operation will be delayed 30 seconds to allow the motorized ball valve to position itself for initial startup.

When Manual BV Control is selected, the user must be careful in setting the analog output because the ball valves will remain in the position set in the Service menu until the control is switched back to Auto or until a technician changes the valves to another manual position (the motorized ball valve in manual mode can be set in 1% increments from fully closed to fully open). Low- or high-discharge pressure may occur during this mode, depending on environmental conditions and the position of the motorized ball valve.

The motorized ball valve is driven by a 2-10VDC proportional control signal: the valve is closed at 2VDC, 50% open at 6VDC and fully open at 10 VDC.

3.2.1MBV Operation After Compressor is Turned Off

Once a compressor has stopped, the MBV control will continue to change the MBV position to main- tain system pressures for a maximum time of 10 minutes by following the auto control algorythm. When the 10-minute delay has expired or the discharge pressure is below its minimum threshold the motorized ball valve will close until the next compressor activation.

3.2.2Service Offset—Changing System Pressure Settings

The MBV control is set to maintain a system pressure specific to the particular type of cooling unit. A properly trained and qualified technician can increase or decrease the pressure through the Ball Valve Setpoint Offset found in the Service/Options Setup menu. The range is 0 to 50 PSI; the default is 30 PSI.

NOTE

Adjusting this parameter will increase or decrease the operating compressor discharge pressure by changing the targeted range of control. The discharge pressure is the peak pressure of the digital cycle.

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Contents
Liebert iCOM Page Table of Contents Teamwork Installing a Liebert Icom UNIT-TO-UNITNETWORKMounting a Large Display on a Wall Figures Tables Features Large and Small DisplaysESC Keyboard icons and functions Icon Key Name FunctionStatus menu, large display, graphical view Accessing Submenus on Large Displays Accessing SubmenusAccessing Submenus on Small Displays Navigating Through the Liebert iCOM MenusEntering a Password Menu tree-Small display, stand-alone or networkedStatus Menu System View Status Menu Unit 1 View User Menu Service Menu UnitAdvanced Menu Unit Viewing Multiple Units with a Networked Large Display Service Menu Unit #Advanced Menu Unit # SET User menu icons Service menu icons Single Unit Functions Unit/Fan Control Start Stop VSD Setpoint VSD Fan Speed Setting Loss of Power Alarm Fan Alarm / Fan Protection Settings AutorestartHigh Pressure Alarm Pump DownCompressor Timing-Units With Two Compressors Digital Scroll High TemperatureCompressor Sequencing Motorized Ball Valve in Digital Scroll Units Service Offset-Changing System Pressure SettingsMBV Operation After Compressor is Turned Off Temperature Proportional Band Temperature proportional bandOne Single-Step Compressor Without Unloaders-One-Step Compressor ControlCompressor Proportional Bands Two Single-Step Compressors Without Unloaders-Two-StepTwo Compressors With Unloaders-Four-Step Two compressors with unloaders four-stepDigital Scroll Compressors Digital scroll capacity modulation, 10-100% variableDelta T Temperature Difference Between Room and Glycol Temperature Control-Second Cooling SourceDifferential Temperatures / Controls Comparator Circuit Chilled Water ControlSecond cooling source and compressorized cooling Glycool Cooling-Free-Cooling Temperature Control-ReheatReheat configuration types Dual Cooling SourceOff ½ Proportional Band Decreasing Temperature Heat On ½ Dead Band 100%Tight Mode SCR ReheatStandard Mode Humidification Dehumidification Humidity ControlHumidification Parameters for infrared humidifier control Humidification Infrared HumidifierExternal Humidifier Control-Optional Dehumidification Low Limit Dehumidification With Comp settingsDehumidification Dehumidification Compressor QuantityControl Types Temperature and Humidity Control TypesReheat During Dehumidification Humidity Sensor Reading Control Types High and Low, Temperature and Humidity Events Supply Limit-OptionalUser Inputs / Customer Inputs Customer inputsEvent Types and Properties Time DelayEnable or Disable Event TypesMain FAN Overload Possible Event Notifications Event notifications-large or small displayCalculation of Next Maintenance and Diagnostics Next Maintenance CalculationCalculating Unit Wellness Fans / Heaters / Humidifier Settings and Diagnostics Parameters for Next Maintenance CalculationGeneral Maintenance Settings Compressor 1 / 2 Settings and DiagnosticsApplication of Teamwork Modes Teamwork ModeTeamwork Modes No TeamworkTeamwork Mode 1 with two cooling units Standby Rotation Typical Standby Lead/Lag Function Standby and CascadeU2U Hardware Cables and Network Switch Placement of Cooling UnitsMinimum Network Switch Requirements Sample Liebert iCOM network configurations Wiring for Unit-to-Unit Communications-U2ULiebert iCOM U2U Ethernet Network Wall-Mount Large Display Wiring a Liebert iCOM U2U Network Small DisplaysLarge Displays Combining Large and Small Displays on a U2U NetworkWiring a small display for stand-alone operation Wiring a large display for stand-alone operation Ports available for connecting Liebert iCOM control devices Liebert vNSA298 84mm 305mm 14.25 362mm DPN001136 Rev Necessary Mounting Items Location ConsiderationsMounting Instructions Liebert iCOM display dimensions Spare part list parameters-large display only Spare Part List-Large Display OnlySetpoints parameters Event log parametersSet alarms parameters Sensor dataActive alarms parameters Active AlarmsDisplay setup parameters Timer parameters-Sleep Mode Total run hours parametersService contacts parameters Service Menu Parameters Unit Diary-Large Display Only Unit diary parametersStandby settings / lead-lag parameters Maintenance / wellness settings parametersWellness COMP2 Wellness HEAT2 Diagnostics / service mode parameters ALM REL 7of Delay Enable Disab Enable Disab Comp 1 Overload Unit X Disconnected WRN Loss of Power LOP MSG, WRN, ALM Call Service MSG, WRN, ALM High Temperature Sensor calibration / setup parameters System / network setup parameters-large display only Network setup parameters GBPStatic RAM Not Available, Invalid, OK Options setup parameters HUM SteamService contact info parameters Service Menu Parameters Service Menu Parameters Page Ti n Ne tIti That
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