User manual

50 Maintenance
UM6C28C P0728920 Standard 11.00 April 2001 Emerson Energy Systems
Troubleshooting
Table 30 provides a list of the problems which can occur on NT6C28C(x)
MFA150 power system, along with their possible causes. Blown fuses and
tripped circuit breakers must always be investigated before referring to this
table.
WARNING
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.
Table 30 – Fault diagnosis
Fault symptom Possible causes
No DC output current  Open AC supply or AC circuit breaker
 Open DC circuit breaker
 Faulty connection between the power shelf and
the controller
 Low voltage disconnect is open
 Sense leads are open
Incorrect indication of
the DC output current
 Incorrect meter calibration
 Loose shunt leads connection
Meter display is OFF Meter display failure
Low voltage  Faulty rectifier(s)
 Shorted battery cell(s)
 Prolonged power failure
 Incorrect float voltage adjustment
 Sense leads are open
 Discharge load is greater than the rectifier's
capacity
 Helios TCM/48 failure ( if provided )
High voltage  Faulty rectifier(s)
 Incorrect Float/Equalize adjustment
Failure to generate
alarms during an alarm
conditions
Incorrect connections between the control and
distribution panel or the rectifier shelves or the
RPM1000C or the TCM/48
Failure to generate an
FA alarm
 Faulty wiring
 Faulty fuse or circuit breaker
 Faulty FA LED
 Loose connection
 Mid trip circuit breaker
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