Switch-Disconnector Type Nal, Alternative Assemblies; Installation; Preparation Of The Switch For Installation; Preparation Of The Supporting Structure - ABB NAL Series Mounting And Operation Manual

Triple-pole switch-disconnector type NAL
and fuse switch-disconnector type NALF

1.0 Switch-disconnector type NAL, alternative assemblies

The Switch-disconnector NAL is supplied by the factory as follows:
1.1 Fully assembled with mechanism and auxiliaries. See item 2.0
1.2 Switch main frame, mechanism and auxiliaries as separate
components, see item 4.0

2.0 Installation

2.1 Preparation of the switch for installation. Fig. 1
For switches with A-mechanisms, the contact knives must be
fully opened by hand and the draw bars connected to the cranks.
Before the switch is test operated, it should be checked that the
surfaces of the main contact are covered by contact grease
(recommended grease: ISOFLEX TOPAS NCA 52).
Test operations
Switches with K-mechanism will close when the operating shaft
is turned anti-clockwise. The switch will open when the operation
shaft is turned clockwise. (Clockwise/anti-clockwise as seen from
the mechanism side of the switch).
When operating switches with A-mechanism, the opening spring is
first charged and latched by turning the operating shaft clockwise.
Turning the shaft anti-clockwise charges the closing spring and
the switch closes. The switches open when the operating shaft is
turned clockwise.
Caution!
Keep well clear of contact knives when operating the switches.

2.2. Preparation of the supporting structure

The disconnectors are intended for vertical or horizontal opera-
tions. The design of a supporting structure shall consider the
geometrical configuration of the disconnector/vertical or horizontal/
and minimal clearances to both earthed and live parts. The sup-
porting structure shall be rigid enough to avoid some deformation
of the disconnector base. All the touching points of the supporting
structure and the disconnector base shall lay in the same plane.
For construction of the supporting structure it is recommended
to use some U-iron or angle iron components. The disconnector
shall be fixed by means of four M12 bolts arranged according
to the dimensional drawing.

2.3. Installation of the disconnector

In the course of installation of the disconnector particular attention
should be paid not to deform the base of the disconnector, other-
wise some defects will occur such as the following:
1. excessive rise of the starting moment of a force on the discon-
nector shaft,
2. non-simultaneity of the contacts which should not exceed
3 mm in normal conditions,
3. deterioration of contacts touch interface in the closed position,
a clearance gauge of 0.05 mm in thickness should not fit bet-
ween the fixed and moving parts of correctly installed
disconnector,
4. displacement of the symmetry plane of moving contacts in rela-
tion to the pole symmetry plane what results in asymmetrical
touching of the fixed and moving contacts. In addition, the ope-
rating lever will hit the lock.
To avoid these defects at resulting from samll deformations of the
supporting structure it is recommended to tighten initially three
bolts only when fixing the base. Some additional washers shall be
placed under the fourth bolts to prevent deformations of the dis-
connector base when tightening the fourth bolt.
Fig. 1 Switch-disconnector type NAL
NAL/NALF – Mounting and operation manual 3