Emerson VISSION 20/20 service manual

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Stop Load = prevents the compressor from loading when the set-point is reached. Set this set-point above normal discharge operating conditions. This set-point should only become active if normal condenser control is not functioning properly, which will cause discharge pressure to become abnormally high.

Force Unload = forces an unload condition when this set-point is reached. This set-point should be set above the “Stop Load” set-point. This set-point will cause the compressor to unload until the discharge pressure lands just above the “Stop Load” set-point.

Low Suction Pressure (Unloading) = This control feature is active in Discharge Pressure or Process Temperature Capacity Control mode. This control feature will limit the compressor from loading when the compressor suc- tion pressure reaches these load limiting conditions. When the set-points are set properly, this control feature will prevent the compressor from experiencing excessive low suction pressure that could result in a low suction pressure failure. The low suction pressure unloading set-points over-ride the Discharge Pressure or Process Temperature Capacity Control Setpoints.

Stop Load = prevents the compressor from loading when the set-point is reached. Set this set-point below normal suction operating conditions.

Force Unload = forces an unload condition when this set-point is reached. This set-point should be set below the “Stop Load” set-point. This set-point will cause the compressor to unload until the suction pressure lands just above the “Stop Load” set-point.

Oil Separator Heater Temperature = These control limits determines when the oil separator heater is turned on and off. A decrease in oil separator temperature below he ON set point turns on the oil separator heater. On an increase in oil separator temperature above the OFF set-point turns off the oil heater.

Liquid Injection Solenoid Control Temp = These set-points determine when the Liquid Injection Solenoid is turned on and off. The solenoid will always be off when the compressor is off. This solenoid can be controlled via the Oil Injection Temperature or the Oil Separator Temperature. This selection in made in the Configura- tion screen.

Oil Pump Restart = The oil pump can be selected either as a full time oil pump (booster applications) or as a part-time oil pump (high stage applications). The selection is accomplished from the Configuration Menu. When the oil pump is selected as a part-time oil pump, then these set-points determine when the oil pump is turned on and off - based on the pressure ratio across the compressor. The pressure ratio is calculated using the absolute discharge pressure and the absolute suction pressure. The pump is cycled on when the pressure ratio is equal to or less than the ON set-point. The pump is cycled off when the pressure ratio is equal to or greater than the OFF setpoint. P.R = Discharge Pressure / Suction Pressure

Volume Slide Adjustment Factor= This value is normally zero. It can be set to a non-zero value to permit a repositioning of the volume slide if it is found that the volume slide is not being positioned such to allow the compressor to run at the most efficient point.

Economizer Solenoid = These setpoints determine when the economizer solenoid is turned on and off. When the percentage of compressor capacity is equal to or below the OFF set-point, then the solenoid is turned OFF. When the compressor capacity is equal to or above the ON set-point, then the solenoid is turned ON.

Hot Gas Bypass Solenoid = These setpoints determine when the hot gas solenoid is turned on and off. When the compressor capacity is equal to or below the ON set-point, then the solenoid is turned ON. When the per- centage of compressor capacity is equal to or above the OFF set-point, then the solenoid is turned OFF.

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Contents Control Panel Page Important Note Page Touch Screen LCD Display Optional Analog Input Jumper Tables Standard Vilter Warranty Page Operational Flow Charts Page Voltage Source Proper Wire SizingVoltage Source Grounding Mixing Voltages Wiring Methods DON’T Touch Screen Description Type Liquid Injection #2 Output Not Defined Page Analog Inputs Page Compressor VFD 20 mA Condenser VFD Slide Valve Position Menu Button Touch Screen LCD DisplayMain Screen LOG on Button IndicatorsMenu Screen Page Compressor Control Time Proportioning Control Auto-Cycle Setpoints Other Setpoints That Might be Required for Motor PID Control Pump-down Pull-down Misc. Control Page Page Alarms and Trips Screen Page Alarms and Trips Page Timers Page Timers Service Options Instrument Calibration Slide Calibration Remove Cover Press Down On Photochopper Command Shaft Rotation Capacity Volume INC DEC CCW Slide Valve Operation Problem Reason Solution Slide Valve Trouble Shooting GuideProblem Replace the actuator. See above Trend Chart Event List Screen Input / Output States Configuration Screens Page Page Maintenance Screen Log In Screen Screen to Add Users User Level Suction Pressure SP#2 Fail Percent Volume FailLow Control Temperature Fail Suction Pressure SP#1 FailLow Oil Injection Temp Fail Auxiliary Safety#1 Input FailLow Start Oil Pressure Fail Low Oil Pressure FailVission 20/20 Troubleshooting Guide Digital & Analog Boards DipswitchesDipswitch Position Digital Output #2 Digital Input Digital Input/Output #1 Digital Input/Output #2 POSITION-1 JP-16 JP-19 JP-22 JP-27 JP-28 JP-29 JP-30 JP-31 POSITION-2 Jumper Position Analog Output Optional Analog Input Jumper Tables Channel #6 Signal Page EmersonClimate.com