Nortech EasyGrid V1, Руководство пользователя

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EasyGrid User Guide
89
11 System Installation
11.1 General
The sensor installation phase should be thoroughly planned before proceeding. Good planning for this
phase means determining the following beforehand:
Where the sensors will be installed.
How the sensor tips will be held in place.
How the sensor cabling will be routed out of the winding.
The semi-conductor of the fiber-optic sensor is located at the end of the fiber-optic cable (sensing tip).
To monitor the temperature of the windings, this tip should be positioned
adjacent to the winding’s
hottest spot. Fix it safely on the conductor such that the winding cannot crush it when there is a sudden
change in current or an abrupt contraction of adjacent coils.
Note
The winding’s hottest spot is determined by the transformer manufacturer’s calculations, to verify these
calculations, the installation of numerous sensors throughout the windings allows heat distribution data to
be collected.
We recommend installation of the sensors using the EasyDisk inside radial winding spacers as described
below but, should it be necessary for any reason to attach the sensor directly to the connector; it is
preferable to tape the sensor side-on against the conductor.
The thermal contact between the sensor and the winding is better with a side-on attachment than an
end-on attachment. In this case, use epoxy resin with crepe paper or insulation paper to hold the sensor
against the conductor, applying a minimum of pressure to the sensor tip (mechanical abrasion of the tip
must be avoided whenever possible).
There are several possible methods of installing the sensors; the following method has the advantage of
using tools and materials readily available on the factory floor. The basic idea is to attach the sensor end
to a radial spacer, install the spacer and secure the sensor “out of harm’s way” until it is time to attach it
to the EasyThrough. Radial spacers are designed to provide physical clearances within a winding so they
mate with axial strips on the winding. Their main functions are to facilitate the flow of oil and provide
dielectric clearance in the transformers. The description that follows assumes that this radial spacer
method is being used.