Factory-assembled pole-mounted 6 (10)/0.4 kV STP transformers are designed for receiving, converting, and distributing three-phase 50 Hz alternating current in transformer systems with neutral is grounded on the LV side.
STP substations are designed to supply power to agricultural facilities, individual settlements, and small industrial facilities.

STP transformer substations comply with the following patents of the Interregional Distribution Grid Company of Center: No. 99905 of 31.08.2010, No. 101278 of 31.08.2010, No. 133982 of 30.04.2013, No. 146463 of 27.01.2014.

 The transformer high-voltage bushings are connected by aerial bundled conductors to overhead wires mounted on crossarms of vertically oriented overhead line supports. The transformer has a load-bearing enclosure also mounted on the vertically oriented overhead line support with a gripper, the side walls of the power transformer have deeply corrugated surface that has a specific feature — mounting projections with holes for surge arresters. In addition, windings of these power transformers are connected to the output terminals of the surge arresters with short jumpers

.The low-voltage switchgear cabinet and high-voltage equipment must be positioned in accordance with the standard layouts. STP substations are connected to the power line through a RLND disconnector or RLK disconnector with an actuator, which can be included into the substation complete set and installed on the nearest support.
These substations perform active or active-reactive electricity metering. At the customer's request, we can install counters of any type.
STP substations are equipped with internal lighting and an outdoor lighting feeder, which turns on automatically after receiving a signal from the built-in photorelay. At the customer's request, we can remove the outdoor lighting feeder.
STP substations are equipped with electrical and mechanical interlocks that ensure safety of the service personnel.
STP substations have protection against the following:
— inter-phase short-circuits —
 atmospheric overvoltage;
— overload and short circuits in 0.4 kV lines;
— short circuits in heating circuits, lighting circuits;
The LV side is equipped with an input disconnect switch and circuit breakers (if requested).
STP substations are designed to work in the following conditions:
— outdoors at ambient temperatures from minus 40 to plus 40°C;
— operating altitude — NMT 1000 m above sea level;
— air environment type (industrial) as per GOST 15150-69;
— non-explosive environment free of critical for equipment performance dust concentrations.
STP substations rated for 16-100 kVA are mounted on one support; those rated for 160 — 250 kVA are mounted on two supports.