11.4.2 Installation
WARNING! Risk of arc flash and electric shock hazard. Open all local and remote electric power
supply disconnect switches, verify with a voltmeter that power is Off and wear appropriate
personal protective equipment per NFPA 70E before working within the electric control
enclosure or the fan motor connection box(es). Failure to comply can cause serious injury or
death.
This unit contains lethal voltage. The line side of the unit disconnect switch remains energized
when the unit disconnect switch is in the “Off” position. Use a voltmeter to verify that the line
side input electric power to the unit disconnect switch is Off before working on any electrical
components or connections.
1. Turn Off the disconnect switch on the enclosure cover.
2. Open the control enclosure cover.
3. Manually turn On the disconnect switch. Power is On and a shock hazard exists with exposure
to hazardous voltage components.
4. If the board can still be powered up and has a display, record the parameter settings. To obtain
parameters go to the C-- menu and press the Up or Down button to read and record the values
for C03-09 and C27.
5. Record all of the DIP switch positions for the CANbus DIP switch package. Retain these for
setting up the new board.
6. Record the positions of the jumpers for J2, J4, J5 and J6 on control board in the unit. Retain
these for setting up the new board.
7. Disconnect power from the Liebert MC by turning Off the main disconnect switch.
8. Use a voltmeter to verify that voltage is no longer present in the unit.
9. Remove the plugs and field-installed wires from the old board. Note the polarity for the
CANbus wiring going to P49 and P50, if present.
10. Mark wires P49-1, P49-3, etc, if they are not already marked.
11. Remove the mechanical fasteners holding the control board in place and remove the old
control board.
12. Install the new control board using the fasteners removed in step 11.
13. Reattach the plugs. Refer to the hot-stamps on the wire harnesses that correspond to the
correct plug on the board. Verify that the plugs are installed properly.
14. Change the CANbus DIP switch positions so they match the control board that was removed. If
the Liebert MC is the second condenser on the CANbus communication line, set Position 1 of
the CANbus DIP switch from On to Off.
15. Change the jumper positions for J2, J4, J5 and J6 to match the control board that was
removed. If the LiebertMC is the last device on the CANbus communication line, move the
jumper at J6 from Pins2 and 3 to Pins 1 and 2 (see Figure 11.4 on the previous page).
16. Power up the unit.
17. Change the parameters to match the parameters from the control board that was removed if
they were obtained from the old board in step 4. See step 18 if the parameters were unavailable.
Vertiv | Liebert® MC™ Installer/User Guide | 121
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