Service And Maintenance - ABB NAL Series Mounting And Operation Manual

15.0 Service and maintenance

WARNING
Do not use any type of alcohol-based cleaners.
This results in weakening of the mechanical
properties of tension rods and can cause
cracking of them. For more info – see last pages!
Cleaning
After maintenance the switch disconnector must be cleaned
before being put into service. Strong solvents and alcoholic
fluids must not be used. For cleaning, water with soap can be
used only. After cleaning, the contact area of the main blades
and the fixed contacts must be greased, type ISOFLEX TOPAS
NCA 52. If the switch-disconnector is placed in a very humid
and polluted area, which will reduce the tracking resistance, it
is recommended to polish the insulators and insulated compo-
nents with Silicon Type DC200 Fluid 100 cst.
Switch disconnectors in service
The switch disconnector should be checked at least once
a year by conducting a number of operations to check all the
functions. The frequency of maintenance depends on the ser-
vice and environmental conditions.
– moving and fixed contacts are greased with – ISOFLEX
TOPAS NCA 52,
– mechanisms do not need any greasing under normal condi-
tions,
Note!
Arcing knives, piston and cylinder must not be greased.
22 NAL/NALF/VR – Mounting and operation manual
Mechanical overhaul
For presently manufactured NAL switches if below specified
service conditions are met, maintenance can be done even
extended to 15-year-intervals:
1. Apparatus must be transported and stored in a genuine box.
2. Service conditions – installation:
a) apparatus must work in indoor application under normal
service conditions – according to IEC 62271:2007 – p.
2.1,
b) apparatus must be installed by qualified staff according
to manufacturer's recommendation,
c) maximum number of mechanical cycles (1,000) must not
be exceeded,
d) maximum values and numbers of the making and breaking
capacity must not be exceeded,
e) safe distances to earthed parts or to other lived parts
must be kept,
f) in special cases (e.g.: fault in the circuit where the NAL/VR
is installed or the apparatus has been overloaded) appara-
tus should be inspected,
g) apparatus is not installed vertically with the hollow insula-
tors at the bottom when it works under condition which
could cause the water condensing in hollow insulators and
arc extinguishing system,
Complete overhaul of the switch disconnector should be car-
ried out after 1000 operations or 5 (15 for new version switch-
es) years in service, preferably by ABB's staff.
Electrical overhaul
The frequency of overhaul depends also on the number of
operations and the magnitude of the breaking current. After
about 100 operations at rated current or about 500 operations
at half the rated current the main contacts, the arcing contacts
and the arc
extinguishing chamber should be inspected and replaced if
necessary.
Replacement should take place when:
– the tip of the arcing contact knives has diminished approx.
3 mm (by minor damage might only cause polishing of the
arcing tip),
– the fixed arcing fingers are burned or do not make any con-
tact,
– the width of the slot in the arcing chamber is more than
8 mm.
If the cooper is visible on any current bus part, then this part
should be replaced by new one.