Earthing transformers are used to obtain a neutral point in compensated or resistor grounded networks. These are the three-phase transformers which in normal working conditions,
while no ground fault occurs, provide power supply to unit auxiliaries. The coil windings are made in the ZNyn11 arrangement, which enables the division of the current between phases and reduces the current on the line which has been exposed to ground fault or short circuiting. The secondary
winding can permanently operate at rated conditions, even if the primary winding is loaded with compensated current. In the event that the network is grounded using a resistor, the neutral point of these devices is connected to an earthing resistor used to input the active component. In compensated networks it is usually combined with an arc-suppression reactor which is used to ensure the appropriate reactance for clearing the arc and earth fault currents.

Manufacturing range:

Power range:  from 150 kVA up to 4000 kVA
Voltage range: up to 36 kV
Current range: 15 A up to 300 A
Isulation class: A according to IEC 60085
Type of cooling: ONAN, KNAN

Standard operating conditions:

Max. operating altitude – 1000 m above sea level
Operating temperature range – 25 to + 40 °C or other on request
Rated frequency 50 Hz (60 Hz on request)

Design characteristic:

Hermetically sealed (without conservator) or with conservator
Core– grain-oriented electrical steel sheets
assembled into core using the “Step-Lap” method
Winding – electrolytic aluminium or copper wire, enamelled round or profiled in paper isolation,
Tank – corrugated or with radiators,
made of steel, painted or hot dip galvanized
Standard colour is RAL7030 or other colours on requestej

Standard equipment:

5-positions off-load tap changer
HV porcelain bushing according to DIN 42531 or EN 50180:2010
LV porcelein bushing according to DIN 42530 or EN 50386:2010
Oil level indicator
Rating plate
Earthing terminals
Lifting lugs
Pulling lugs
Bi-directional wheels
Thermometer pocket
Filling plug
Draining device according to EN 50216-4 or DIN 42551
Painting RAL 7030

Optional equipment:

7-positions off-load tap changer
Protection relays DMCR® or DGPT2®
Plug-in bushings
Busbars bushings
Surge arresters
Antivibration pads
Cable boxes
Accessories for conservator: dehydrating breather,buchholz relay, drain plug, oil level indicator

Making, testing & loss levels, tolerance ranges are in compliance with IEC 60076-1, IEC 60076-6