Three Phase Distribution Transformer for Power Supply

A three phase distribution transformer is a transformer used to convert medium voltage electricity into low voltage electricity for three-phase distribution systems. It is widely used in local power networks because most industrial facilities, commercial buildings, public infrastructure, and utility distribution systems rely on three-phase power for efficient load supply.
The main purpose of a three phase distribution transformer is voltage step-down. Power from a medium voltage feeder, switchgear cabinet, overhead line, or ring main unit enters the transformer at the primary side and is converted to a lower voltage at the secondary side. The low voltage output can then supply motors, lighting circuits, HVAC systems, pumps, elevators, chargers, production equipment, and other electrical loads.

TSTY supplies three phase distribution transformer solutions in different structures. Oil-immersed transformers are often used in outdoor substations, utility networks, industrial yards, rural feeders, and compact substations. Dry-type transformers are commonly selected for indoor electrical rooms, commercial buildings, hospitals, schools, data centers, and areas where oil-free installation is preferred. Pad-mounted and pole-mounted transformers can also be selected according to installation conditions.
The technical selection of a three phase distribution transformer should include rated capacity, primary voltage, secondary voltage, frequency, vector group, impedance, tap range, insulation level, winding material, cooling method, noise requirement, loss level, and short-circuit withstand requirement. Site conditions such as altitude, ambient temperature, humidity, dust, ventilation, corrosion exposure, and indoor or outdoor installation should also be confirmed before quotation.
A three phase distribution transformer must also match the load type. For motor-heavy industrial systems, starting current and load fluctuation should be reviewed. For commercial buildings, transformer sizing should consider HVAC operation, elevators, lighting, office equipment, and future load expansion. For utility distribution, overload practice, line voltage drop, grounding method, protection fuses, and transformer placement are important.
TSTY can help buyers coordinate the three phase distribution transformer with upstream and downstream equipment. On the medium voltage side, the transformer may connect with RMU switchgear, MV circuit breaker panels, load break switches, fuses, or overhead line protection. On the low voltage side, it may connect with LV switchboards, busbar trunking, metering panels, capacitor banks, and distribution feeders.
For compact substation projects, the three phase distribution transformer is usually arranged between the MV switchgear compartment and the LV distribution compartment. In this case, enclosure dimensions, ventilation openings, transformer access, cable routing, grounding layout, and maintenance clearance should be reviewed as one system. For outdoor pad-mounted installation, foundation design, cable trench position, protection level, and operation access should be confirmed.
Before ordering a three phase distribution transformer, buyers should provide rated power, voltage ratio, frequency, connection group, impedance requirement, tap changer type, cooling method, installation method, enclosure requirement, accessory list, applicable standards, and required documents. If the transformer is used for export projects, packing method, transport limits, nameplate language, test reports, and destination climate should also be discussed.
TSTY can provide datasheets, outline drawings, routine test reports, accessory details, packing information, and nameplate information according to the agreed supply scope. A suitable three phase distribution transformer helps the project team connect medium voltage supply, transformer performance, low voltage distribution, and site installation requirements in a practical way.