33/44/55 MVA Power Transformer

In 2024, Daelim Transformer provided two 33 MVA / 44 MVA / 55 MVA step-up power transformers for a solar power project in the United States. The design and construction of these transformers comply with IEEE standards and relevant regulations. Both transformers feature a three-phase, three-winding, oil-immersed construction with a conservator.

Transformer Specifications:

• Transformer 1:

  • High Voltage: 138 kV
  • Medium Voltage: 34.5 kV
  • Low Voltage: 13.8 kV

• Transformer 2:

  • High Voltage: 69 kV
  • Medium Voltage: 34.5 kV
  • Low Voltage: 13.8 kV

Both transformers are equipped with a two-stage forced air cooling system:

• Self-Cooling Capacity: 33 MVA
• One Fan Operating (ONAF1): 44 MVA
• Two Fans Operating (ONAF2): 55 MVA

Construction Details:

• Windings: Copper
• Core Material: High-quality, low-loss cold-rolled silicon steel
• Insulation Liquid: Mineral oil, compliant with ASTM D3487 standards
• Bushings: Top cover design, porcelain type, ANSI Segment 2 Number, ANSI 70 Gray
• Oil Preservation System: Conservator

Environmental Conditions:

• Location: Harrington, DE
• Site Elevation: 60 ft
• Ambient Temperature Range: Minimum -20°F, Maximum 110°F
• Weather/Load Criteria:
  • Radial Ice Buildup: 0.5 in
  • Wind Speed: 100 mph
  • NESC Loading District: Heavy
  • Contamination per IEEE C57.19.100: Heavy

Instrument Transformers:

• High Voltage Bushing CTs
• High Voltage Neutral Bushing CT
• Low Voltage Bushing CTs
• Low Voltage Neutral Bushing CTs
• Tertiary Winding
• ANSI Accuracy Class: C400

Arresters:

• High and low voltage stations class porcelain arresters, ANSI 70 Gray

Accessories:

• Liquid-Level Indicator
• Liquid-Temperature Indicator
• Winding-Temperature Indicator
• Pressure-Relief Device
• Rapid Pressure Rise Relay
• Buchholz Relay
• Pressure-Vacuum Gauge
• Pressure-Vacuum Bleeder
• Pressure Test and Gas Sampling Valve
• Drain and Filter Valves
• Removable Radiators and Isolation Valves
• Transformer Monitoring System
• Dry Air Fill Valve

Testing:

All routine tests as per Table 21, C57.12.00, and accompanying notes, in accordance with methods and procedures outlined in C57.12.90, including:

• Insulation Power Factor Test
• Audible Sound Level Test
• Insulation Resistance Test by Megohmmeter
• Core-Ground Resistance Test
• Temperature Rise Test
• Positive and Zero Sequence Tests
• Short-Circuit Tests
• Seismic Tests
• Sweep Frequency Response Analysis
• Dissolved Gas-in-Oil Analysis
• Front-of-Wave Impulse Tests
• Switching Impulse Tests
• Partial Discharge (PD) and Radio Influence Voltage (RIV)

Preparation for Shipment:

• Radiator cooling units are crated securely for protection, with silica gel bags installed inside each radiator to absorb moisture. Bags must be affixed securely to a ring weld inside blank-off covers.
• Heavy parts are placed on skids for handling, securely boxed, and identified by content.
• Exterior electrical receptacles are covered for protection.
• Hollow external bracings have drain holes.
• Transformers are equipped with a GPS travel recorder to register shocks in three dimensions: travel direction, vertical, and transverse side-sway.

Transformer Shipping:

• Transformers are filled with dry nitrogen.
• The shipping marker indicates pressure and temperature when sealed for shipment.
• A pressure gauge is mounted on the transformer to show tank pressure upon receipt by the buyer.
• Draw leads for HV bushings are tied to suitable clips welded to the underside of shipping covers over bushing openings.

Warranty:

• 24months from the date of manufacture .