User manual

Maintenance 65
Emerson Energy Systems MFA150 Power System  NT6C28C User Manual
Procedure 9 – Replacing a distribution circuit breaker
Step Action
1 Notify the alarm center of possible incoming alarms during this
procedure.
2 Open the front door and remove the top panel of the control and
distribution panel.
3 Operate the circuit breaker to be replaced to the “OFF” position
(down).
4 Disconnect the “NC” or “NO” alarm wire from the circuit breaker to be
replaced.
5 Use a properly insulated wrench to remove the hex nut holding the
circuit breaker and the “C” alarm wire to the top busbar, then the hex
nut holding the circuit breaker to the bottom busbar.
6 Carefully remove the circuit breaker from the distribution panel by
pulling on it forward.
7 Ensure that the new circuit breaker is in the “OFF” position. Remove
also the small “L” shaped busbar from the new circuit breaker.
8 Align the new circuit breaker with the appropriate position and insert
the studs into the holes in the top and bottom busbars.
9 Use a properly insulated wrench to secure the hex nut holding the
circuit breaker to the bottom busbar.
10 Install the “C” alarm wire on the circuit breaker itself.
11 Use a properly insulated wrench to secure the hex nut holding the
circuit breaker and the “C” alarm wire to the top busbar.
12 Connect the “NC” or “NO” alarm wire to the circuit breaker as shown
in Figure 23, depending if standard trip or mid trip circuit breakers are
used ( see note below Figure 23 ).
13 Reinstall the top panel and close the front door of the control and
distribution panel.
14 Notify the alarm center at the end of the procedure.
–end–
Replacement of the LVD contactor
WARNING
Precautions to take to avoid service interruptions
Make sure to use properly insulated tools when working
inside the control and distribution panel.