250 kVA Oil-Immersed Distribution Transformer

250 kVA Oil-Immersed Distribution Transformer is specified for 250 kVA oil-immersed distribution service. It uses ONAN cooling. Engineering details address heavy-Duty Load Management, construction, application context, and electrical data for project selection.

Heavy-Duty Load Management

For this 250 kVA rating, heavy-duty load management affects how the transformer is selected, protected, and operated in the field.

• It represents a critical threshold in power distribution, often serving as the dedicated power supply for standalone facilities or facility wings.
• Unlike smaller pole-mounted units, this transformer is engineered to manage substantial continuous currents (approx.
• 360A at 400V) with superior thermal stability.
• One of the distinct advantages of this oil immersed transformer over dry-type alternatives is its high thermal inertia.
• The specific heat capacity of the mineral oil allows the unit to absorb and dissipate heat generated during temporary overload spikes-common in industrial motor startups-without triggering immediate temperature alarms.

Advanced Winding Technology: Foil vs. Wire

The advanced winding technology: foil vs. wire details below highlight design choices that matter during continuous distribution service.

• At the 250 kVA capacity level, mechanical strength becomes paramount.
• The design uses LV Foil Winding Technology for the low-voltage coils, a significant upgrade from the wire-wound technique used in smaller transformers.
• Zero Axial Forces: By winding the full width of the coil with copper or aluminum foil, we effectively balance the ampere-turns.
• This means that during a short-circuit event, the axial forces (which can tear a transformer apart) are virtually eliminated.
• Cooling Efficiency: The foil structure eliminates internal air gaps found in wire windings.

Protection and Monitoring

These protection and monitoring points connect the electrical rating with grid conditions, downstream equipment, and maintenance expectations.

• To ensure longevity, the tank is equipped with essential monitoring devices.
• A dial-type oil thermometer allows operators to visualize the top-oil temperature directly.
• For enhanced safety, we integrate a pressure relief valve that activates if internal pressure exceeds safe limits (typically 0.30 - 0.35 bar) due to a fault, preventing tank rupture.
• Pressure relief valve installed on 250 kVA oil transformer for explosion protection.

Primary Application Sectors

Application guidance links the transformer rating with the substations, industrial loads, and site conditions where it is normally used.

• The 250 kVA unit is the "workhorse" size for specific facility feeds: 1.
• Schools and Hospitals: Providing reliable power for lighting, HVAC, and sensitive medical equipment.
• Small Factories: Ideal for powering a specific production line with multiple motors.
• Shopping Centers: Dedicated supply for refrigeration units and escalator systems.
• 250 kVA oil immersed transformer providing reliable power supply for commercial buildings and schools.

Electrical and Mechanical Data

The electrical data summarizes the main values needed for project comparison and project comparison.

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