Dry transformers

Replacement of oil transformers for dry transformers brings many benefits:
First, the use of a dry type transformer brings economic benefits. Due to their high fire safety dry transformer can be placed very close to the final consumers of electricity, which makes it significantly reduced the losses arising from the transmission of electricity in low voltage.

Secondly, this is a unique opportunity to install dry transformers in near places equipped with water and in places where there are specific requirements for the protection of the environment and they are perfect to install them at the subway and near nuclear power plants, etc. .
In addition, the installation of dry transformers there is no need to make special recesses for the reception of oil and installing extinguishing agents. This allows the installation of dry transformers on different floors of the building.

Dry transformers do not require time-consuming maintenance: There is no need for sealing of the transformer tank and its protection against corrosion, as well as cleaning of the oil.
Dry transformers with cast resin insulated coils require only air cooling. There is no need to control the oil level, as well as its purity. Dry transformers resin withstand short-term load peaks, for example at start of electric motors.

Design features

The company “Transformer Service” produces dry three-phase distribution transformers with cast resin insulation coils and capacities from 100 to 2500 kVA. Primary windings on the high voltage with ratings for 6 or 10 kV and a low voltage of the secondary winding 0.4 kV.
Dry transformers are manufactured in accordance with GOST standard 11677-85 “Power transformers. General technical requirements”, DSTU 3076-95 (GOST 30297-95) “Dry power transformers. Technical requirements.” Specifications TUU31.1-31617591-004: 2013 “Transformers TSL, TSZL with cast resin insulation coils and capacities from 100 to 2500 kVA for 10 kV voltage”

Working conditions:

– Installation height above sea level – up to 1000 m;
– The environment temperature from -25°C to + 40°C.

Brief description of dry transformers

Dry transformers are fire-resistant and can withstand very well work under short circuit conditions and are easy to maintain and environmentally friendly. Thermal insulation class – F (155˚C). Cover protection IP – 00 (without cover), IP – 21 and IP – 23 (with protective cover).

Low voltage windings are made of aluminum or copper foil. High voltage windings are made of aluminum or copper wire. Scheme and connecting group and position of the bushings HV and LV as well as type of bushings (rail or wired) according to customer orders.

Dry cast resin transformers are equipped with thermal sensors and relays, which first give a warning and then a signal to disconnect the transformer from the power supply when the temperature exceeds acceptable temperature standards for cast resin windings (145˚C – warning signal 165˚C – a signal to switch off).
Dry transformers are produced for rated voltage of the primary winding 6 or 10 kV.
Rated voltage of secondary windings is 0.4 kV. Scheme and connection group is Yyn-0 or Dyn-11.
On request, we can make transformers with other voltages, as well as the scheme and connecting group.

Voltage regulation is carried out without a load when the transformer is disconnected from both the high (HV) and low (LV) side.

The voltage is regulated on the high side (HV) ± 2×2.5% of the nominal value.
Dry transformers are equipped with thermal sensors (one for each winding LV), which are connected to a terminal and connected to a temperature controller, which is not included in the price and is available on request.
Dry transformers are equipped with wheels or at the request of the customer supplied with anti-vibration pads.

Technical characteristics of the dry transformers

Capacity, kVA Nominal windings voltage, kV Scheme and connection group of windings Short-circuit voltage, % Losses, kW Load current,%
Load/td> No-load
HV LV 75˚С 120˚С
100 6, 10 0,4 Yyn-0 Dyn-11 4,0 1,7 1,955 0,44 2,4
160 6, 10 0,4 Yyn-0 Dyn-11 4,0 2,3 2,65 0,61 2,2
250 6, 10 0,4 Yyn-0 Dyn-11 4,0 3,0 3,45 0,82 2,0
400 6, 10 0,4 Yyn-0 Dyn-11 4,0 4,3 4,95 1,15 1,9
630 6, 10 0,4 Yyn-0 Dyn-11 4,0 6,4 7,35 1,5 1,45
1000 6, 10 0,40 Yyn-0 Dyn-11 6,0 8,8 10,1 2,0 1,4
1250 6, 10 0,40 Yyn-0 Dyn-11 6,0 10,4 12,0 2,4 1,35
1600 6, 10 0,40 Yyn-0 Dyn-11 6,0 12,7 14,6 2,8 1,3
2500 6, 10 0,40 Yyn-0 Dyn-11 6,0 20 23 3,3 1,2

Transformers in this section