ABB MNS R - Repair Operations for Possible Malfunctions

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1TTS900001M0902
MALFUNCTION POSSIBLE CAUSE REMEDY
1. Malfunction of circuit breakers or
apparatus installed in the switchboard
See the related installation,
operation and maintenance
instructions
See the related installation,
operation and maintenance
instructions
2. Compartment or unit heating
abnormalities
Ventilation grids and/or ducts
blocked
Clean by means of a vacuum
cleaner and check the upper
grids
Connections between busbars,
joints and/or terminals not properly
tightened
Check the status of the contact
surface, then tighten according
to the tightening torques
indicated in Appendix A
Improper setting or malfunction
of the anticondensate heater
thermostat
Set properly the thermostat. If
necessary, replace it
3. Condensation formation Malfunction of the anticondensate
heater or of the related power
supply circuit
Search the cause; if necessary,
replace the anticondensate
resistance (ask ABB SACE)
4. Automatic controls do not function Component malfunction Search the possible cause by
referring to the switchboard
operation diagram. If necessary,
ask SACE
5. Unwanted trip of circuit breakers • Impropercoordinationofthe
protection
• Overheatingcausedbyloosen
connections or dirty or oxidated
isolating contacts
• Failurecausedbythe
overcurrent releases
• Accordingtosystem
selective diagrams, check
the correspondence of the
maximum current release
device setting of the relevant
circuit breakers
• Cleanwithsolventthe
isolating contacts both
of fixed parts and circuit
breakers, then lubricate with
vaseline greese
• Ifthefailureiscausedby
the overcurrent release,
check first the temperature
inside the circuit breaker
compartment. See also the
circuit breaker instruction
manual
6. Humming of the metallic structure Screws loose of the segregation
plates (if equipped) or of the
external closing panels
General check of the
segregation plate fixing or
external closing panel
5.4 Repair Operations for Possible Malfunctions
Each maintenance operation must be performed only by qualified personnel,
always observing the safety rules.