Emerson Liebert iCOM Manual De Usuario

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.

This standard Liebert iCOM feature cuts unit restart time to 15 seconds without adding additional 

power capacitors or battery backup. The quick start allows unit to start fan and modulate the chilled 

water valve open to predefined points while the Liebert iCOM is booting up. Once the control boots, 

Liebert iCOM holds the chilled water valve and fan at these predefined points% until the call for 

cooling and fan is established and then releases the valve and fan control to normal operation. Chilled 

water quick start is available on all chilled water actuator types. Contact your local Emerson 

representative or technical support for more information on enabling this feature.

The actuator response time and actuator positioning can be improved by implementing valve 

feedback. Enabling the feedback signal will eliminate the need for floating point actuators to drive the 

valve closed after a loss of power or Unit Off command, decreasing the unit's restart time. Feedback 

provides analog and floating point actuators provides with enhanced actuator failure detection. Valve 

feedback is available only on Liebert single and dual valve CW models; feedback is not compatible on 

units with fluid economizer.
Valve feedback allows the control determine the valve position by timing how long the open or closed 

signals have been active based on the valve travel time set in the Service menu / Setup submenu. To 

determine the initial position of the valve, the unit must perform a 3P Reset. The 3P Reset closes the 

valve for a time of 110% of the 3P Actuator run time. This calibrates the valve with the controller and 

ensures that it is closed. A 3P Reset is also performed if the fan is switched Off for any reason (timer 

Off, unit Off, etc.). 
Special wiring is required for implementing valve feedback on analog actuators. Signal floating point 

actuators are factory-wired (P22) to accommodate feedback. Authorized Emerson personnel should 

use the following steps to enable the feedback signal:
1. Turn unit Off at the display.
2. The Feedback Signal Connects To Analog input 1 on signal circuit units. The second circuit on 

dual circuit models connects to Analog Input 2. Nothing can be connected P11 Pins 1 through 4 on 

signal circuit units and P11 Pins 1 through 8 on dual circuit units.

3. Control board DIP switch SW2 Switch 1 must be On, 2 must be Off, 3 must be On and 4 must be 

Off.