User manual

Maintenance 53

Emerson Energy Systems

MFA150 Power System

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NT6C28C User Manual

CAUTION

Precautions to take to avoid service interruptions

When working on a live power system, the low voltage

disconnect contactor (if provided) should be kept from

tripping. To do this, insert a 1/4-inch ( 3 mm ) wide

electrically isolated tool ( preferably plastic ) in the small

opening on the side of the contactor assembly to lock it

closed. See Figure 19.

Procedure 1 – Replacing the NT6C14PF controller card

Step Action

Notify the alarm centre of the possibility of incoming alarms during

the execution of this procedure.

If possible, use the TEST mode to record the existing alarm settings

of the control card.

Remove the top cover and open the front door of the control and

distribution panel.

If the system is provided with an LVD feature, insert a 1/4-inch ( 3

mm ) wide electrically isolated tool in the small side opening of the

contactor assembly to lock it closed as shown in Figure 19.

Remove the sense fuse on the front door of the control and

distribution panel and open the connector going to the controller

card.

Disconnect and insulate the red lead coming from TB3-4 on the

battery (–) charge busbar.

Remove and tag the power leads on TB3-3 and TB3-4 of the

controller card, as well as all the other alarm and control leads on

terminal block TB1, TB2 and TB3.

Unplug the rectifier and power plant alarm cable assemblies from

connectors J1 to J7.

Remove the mounting screw securing the controller card in place,

then pull the card slightly forward, slightly to the right, and pull it

forward completely to remove it.

Install the new card by reversing the operation in step 10 and

securing it in place with the mounting screw.

Reconnect all wires and cables by reversing steps 6, 7 and 8.

12 Adjustments

Put the BYPASS/NORMAL switch in the BYPASS position. The TST

BYPASS indicator should light up.

Connect an external digital multimeter set for a 60 V dc reading

across the test points located on the front of the control and

distribution panel.

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