6-10 Kv Three-phase transformers ТМЗ, ТМФ type

ТМЗ: dimentions & weight characteristics

  ТМЗ type transformers: are designed for transformer substations and provides oil protection against oxidation and compensates oil volumetric temperature variations. Another distinguishing feature of this type, the LV and HV bushings gets out on the narrow side of the transformer, which significantly reduces their installation dimensions in height and width, and thus the size of transformer substation.

  ТМФ (flange type transformer): similar to ТМЗ, excluding nitrogen cushion. Instead, on that transformers type the extender which ensures the necessary oil volume at various ambient temperatures.

  Technical data
  ТМЗ, ТМФ power transformers are available with primary windings voltage (high voltage) up to 10 kV inclusive and the secondary windings (low voltage) – 0.4 or 0.69 kV.
Diagram and winding connection group Y/Yn-0; ∆/Yn-11; Y/Zn-11.
For voltage adjustment, the transformers are equipped by high-voltage switch. The switch allows to adjust the voltage in steps of 2.5% on the value of ± 2 x 2.5% of the nominal value while the transformer is disconnected from the mains both the LV and HV. The switch is connected to HV winding. According to GOST 11677, the maximum tolerances of transformers technical parameters are:
- Short circuit voltage ±10%;
- Short circuit losses on the main branch +10%;

- No-load losses +15%;
- Total weight +10%.

  ТМЗ(Ф)-XXX/6(10) У(ХЛ)1 symbol structure:
Т - Three - phase transformer;
М – natural air cooling with natural oil circulation;
З - Nitrogen cushion oil protection;
Ф - flange type transformer;
XXX - rated power, kVA;
6(10) - HV windings voltage class, kV;
У(ХЛ)1 – climatic composition and accommodation category as per ГОСT 15150-69;
  Terms of use:
Altitude – up to 1000 m.
  Ambient temperature:
- for a temperate climate - from –45^ОС to +40^ОС («У» composition);
- for a cold climate - from –60^ОС до +40^ОС («ХЛ» composition).
Relative humidity– less than 80% at +25^ОС.
The transformers are not suitable for operation:
- In the explosive and corrosive medium (containing gases, vapors, dusts and others in an increased concentration);
- Vibration or shock;
- With frequent on-load reconnections on the feeding side - more than 10 times per 24 hours.
The Transformers Design:
  The transformers tanks are welded, rectangular shape. To increase the cooling surface, radiators are used. For lifting (movement) a tank and an entire transformer, the hooks arranged at the upper frame of the tank are used. There where a valve (tube) on the tanks cover, and another tube for pouring oil is placed at the bottom of the tank. Also the bottom has drain plug oil valve (tube) for sampling, and grounding bolt.
  The active part consists of a magnetic core, made of cold rolled electrical steel, windings and the high-voltage switch. Its lifting (movement) arranged by eyelets located at the top of the core.
  Transformers windings are made of aluminium wire.
HV and LV bushings are for outdoor installation type, removable, with porcelian insulators. The bushings are located on narrow sides of the tank. An oil indicator, for oil level monitoring, is mounted on the oil-nitrogen-expander sidewall. The oil indicator has three check marks corresponds to oil levels into non-operated transformers at a different temperatures:
–45^ОС, +15^ОС, +40^ОС - for «У» performance; 

–60^ОС, +15^ОС, +40^ОС - for «ХЛ» performance; 
and also the check line corresponding to oil level at sealing temperature.
  A nitrogen cushion ensures oil protection of oxidation and compensates oil volumetric temperature variations. To measure the upper layers temperature, thermometric detectors are installed in the tank. For monitoring the internal pressure and signaling about the maximum permissible pressure values, vacuum manometers are installed. A protective safety diaphragm or a pressure switch, which will be triggered when the pressure reaches 0.75 atm, inslalls into tank and lets gases escape outside.
  In case of ТМФ transformer, the expansion tank operating similarly to TM transformers.