Cast-resin transformers

TECHNICAL CHARACTERISTICS All transformers are manufactured in accordance with the following specifications:

- CEI 14-4 n° 609 power transformers
- CEI 14-8 n° 1162 dry power transformers
- IEC 60076-11
- CENELEC HD 538-1/HD 464

PHOTOGALLERY

CONFORMITY WITH CLASSES
Environmental
E0: tranformer suitable to be used in clean and dry environment. E1: tranformer suitable to be used in presence of occasional condensation an dlow pollution.
E2: tranformer suitable for being installed in highly polluted environment and with presence of substantial condesation.
Climatic
C1: tranformer suitable for being used with ambient temperature up to - 5°C; the transformer can be delivered and stocked with an ambient temperature uo to - 25°C. C2: tranformer suitable for being used and stocked with an ambient temperature uo to - 25°C.
Fire Behaviour
F0: tranformer suitable for being used in environment without fire risk. F1: self-estinguishing transformer which does not give out toxic substances and mette smokes.

The respect of the application of such norms is guaranteed from the organisation business quality: ISO 9001:2008 - NET N° IT-55187 - RINO N° 16239/07/S.


MAGNETIC CORE
It is assembled of oriented-crystal ferrosilicon laminations carlyte insulated, cut into figures to be assembled with 45° joints and with three vertical columns. The figures are cut and assembled sith special equipment to reduce work losses. The columns are locked shrink strips; the yokes are tightened with metallic armatures with are insulated from the laminations and suitable for a correct tightening of both LV and HV windings. After the core is erected, a double surface painting is carried out so as to guarantee a protection even from chemically aggressive substances present in the atmosphere an to obtain a considerable noise reduction.

LV WINDINGS
They are made of an aluminium conductor (UNI 4507 Standard) with rounded edges, insulated with a special resinenamelled film. The coils are made by winding simultaneously the conductor tape, the turn and the insulator with semiautomatic winding machines in order to obtain a high quality compact assembly of resisting short circuit radial compression forces without any risk. A subsequent vacuum resin treatment followed by an over hardening treatment guarantees a permanent protection of the winding from moisture infiltration. The terminals for the connections to cable or busbars are opportunely moulded during the winding operation; they consist of a conductor plate with electrolytic copper surface.

HV WINDINGS
They are made of single coils of aluminium strip or wire. The coils are would together with an insulating film, stacked up in a special mould where, after the vacuum heat treatment, filled epoxy resin is cast. After a polymerisation and stress relieving process with controlled time and temperature, a compact column is obtained with windings protected by a suitable resin thickness so as to guarantee the insulation beetween the turns. This technology allows to manufacture environmental agents. The resin used has excellent self-extinguishing and non-flammable characteristics (E2 - C2 - F1)

REGULATOR OF THE TRANSFORMATION RATIO
Special terminal boards on each HV column can be adjusted when the transformer is disconnected form the HV and LV.
This allows the regulation of the transformer ratio for variations of +/- 2/2.5% and, if mounted, the facility to adjust the supplied voltage to units with two primary voltages.

COLUMN BEARINGS
The HV and LV windings are supported and locked by means of elastic insulating bearings anchored to the core armature. These bearings allow an axial compensation of thermal expansions and an attenuation of the vibrations due to load variations due to load variations.

STANDARD ACCESSORIES
- Standoff insulators with thread bush for connections to hv line;
- Attachment plates for connections to lv line and neutral;
- Terminal boards to change voltages hv +/- 2/2.5%;
- Pulling holes;
- Truck with rollers (unel 21014-88) to move the transformer forward and backward;
- Rating plate (unel 21014-88);
- Earth terminals (unel 06131-71);
- Three temperature sensors placed in each lv column with outlets brought into theterminal box.

OPTIONAL ACCESSORIES
- Protective box with removable front panels;
- Vibration-domping mounts for truck rollers;
- Hv line connections with detachable connectors;
- Core temperature indicator with alarm and trip contact;
- Forced ventilation units

APPLICATIONS AND ADVANTAGES
Gritti transformers can be set in every environmental place because they are entirely built with insulating materials, retarding the flame and autoestinguishing. They can be set where it is difficult to use oil transformers such as in public buildings, galleries and on ships.

TEST AND TESTINGS
All the transformers are submitted, in our room test, to test according to CEI 14-4-8 and IEC 76 norm. They are equipped of a manual, they contain a testing bulletin and all accessories to application.

The transformers are guaranteed 24 months.