67kV 8400kVA/10500kVA Three Phase Power Transformer

Additional information

Primary Voltage Ratings: 67 kV

Secondary Voltage Ratings: 4.16 kV

H.V. TAP RANGE: 67kV±2×2.5%

CONNECTION TYPE: Dyn1

TYPE: Three phase oil transformer

BIL: 350/75kV

Standards: IEEE

Application: Utility

Power Rating: 8400 kVA/10500 kVA

Cooling Method: ONAN/ONAF

In November 2024, Daelim Transformer successfully completed and fully tested two 67kV, 8400kVA/10500kVA three-phase power transformers. These transformers have been delivered to customers in the United States for use in a utility project in Minnesota.

67kV Transformer Technical Specifications
POWER RATING	8400/10500kVA
RATINGPRIMARY VOLTAGE	67000DELTA
SECONDARY VOLTAGE	4160GRDY/2400
FREQUENCY	60Hz
VECTOR GROUP	Dyn1
WINDING MATERIAL	COPPER
LOAD LOSS AT RATED VOLTAGE	14500W AT ONAN
NO LOAD LOSSES	4000OW AT ONAN
IMPEDANCE	8% AT 7500 kVA
ALTITUDE	≤1000m
COLOR	ANSI 70 GREY
OIL WEIGHT	13,889LBS
TOTAL WEIGHT	53,572LBS

Contact Daelim Transformer for special requirements

sales@daelim-electric.com
pingruidan@gmail.com

Fittings And Descriptions
VALVES FOR PURGING AND TESTING	TAP CHANGER
OIL DRAIN VALVE	LIFTING LUG
LADDER	JACK POSITION
NAMEPLATE	CT TERMINAL BOARD
GROUNDING CONNECTOR NUTS	OIL LEVEL GAUGE
3’’BRASS OI FILLING VALVE	COOLING FANS(DBF2-)
MANHOLE	COOLING RADIATOR(PC-)
FALL PROTECTION BASE ANCHOR	JPPER FILTERING VALVE
LV CT	WINDING TEMP INDICATOR
LV AND LV.N CT	OIL TEMPERATURE INDICTOR
HV CT	EARTHING BUSHING FOR CORE
SURGE ARRESTERS FOR L.V	VACUUM PRESSURE GAUGE(QUALITROL )
LV BUSHING(5KV,2050A)	CONTROL BOX NEMA-3R STAINLESS STEEL
HV BUSHING(72.5kV,630A)	BRASS VALVE FOR FUTURE GAS MONITOR SYSTEM
SURGE ARRESTERS FOR H.V	PRESSURE RELIEF DEMCE WTH CONTACT(QUALITROL)
ROUND STEEL PADS	2″BRASS GATE VALVE FOR FUTURE SUDDEN PRESSURE RELY

Core Features

Designed in accordance with IEEE Std. C57.12.00, ensuring safe and reliable operation.

Temperature rise is designed for 55°C/65°C, which enhances the transformer’s service life, improves safety, and reduces energy consumption and maintenance costs.

The transformers feature a two-stage air-cooled design with a fan-assisted cooling system that improves heat dissipation efficiency. This system offers low maintenance costs, high adaptability, and is suitable for high-load, medium-to-high power applications.

Equipped with remote monitoring contacts for real-time operational status tracking.

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Cooling System (ONAN/ONAF)

The transformer is an oil-immersed, air-cooled type that enhances heat dissipation through a fan-driven air flow.

Under natural air cooling (ONAN), the rated capacity is 8.4MVA
When the fan operates (ONAF), the rated capacity increases to 10.5MVA

This cooling system efficiently handles sudden increases in load or temperature. The fan automatically activates when required, ensuring continuous operation under varying conditions.

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Cooling System (ONAN/ONAF)

Instruments and Monitoring

The 67 kV transformers are equipped with a variety of advanced instruments, including remote monitoring capabilities, to ensure optimal performance and safety:

Oil Level Indicator: Equipped with two alarm contacts to signal when the oil level inside the tank is too high or too low.
Oil Temperature Indicator: With alarm/trip contacts to trigger an alarm or trip the system if the oil temperature exceeds 65°C/90°C.
Winding Temperature Indicator: Featuring four contacts, this indicator allows users to set alarm thresholds at 60°C or 75°C, and trip settings at 105°C or 125°C, cutting off power to protect the transformer and associated equipment.
Vacuum Pressure Gauge: Includes two alarm contacts to monitor internal pressure changes. It activates an alarm when pressure reaches a critical threshold.
Pressure Relief Device: Equipped with alarm/trip contacts to trigger an alert and automatically release excess pressure if the internal pressure exceeds safety limits. If the pressure continues to rise or the valve fails to function, the system will trip, disconnecting the transformer to prevent equipment damage.

These gauges ensuring reliability and effective monitoring of transformer health, enabling timely detection of potential issues to prevent equipment failure and safety hazards. The vacuum pressure gauge and pressure relief device are sourced from the renowned brand Qualitrol.

Insulation

High-voltage side: 67kV, with a BIL rating of 350kV, designed to withstand transient overvoltage shocks up to 350kV without insulation failure.
Low-voltage side: 4.16kV, with a BIL rating of 75kV, capable of withstanding transient overvoltage shocks up to 75kV without insulation failure.

Control Box

67kv 8.4mva 10.5mva transformer control enclosure
The transformer is fitted with a NEMA 3R standard stainless steel control box, which is suitable for outdoor use. The enclosure is waterproof, dustproof, and corrosion-resistant, ensuring durability and reliable performance under harsh environmental conditions.

All instruments, meters, fan contacts, and related circuits are integrated into this NEMA 3R control box, providing a centralized location for monitoring and control.

Daelim Transformer’s Global Expertise

Daelim Transformer has extensive experience in delivering high-quality transformers for utility projects worldwide. We offer tailored solutions to meet the specific needs of your projects. Contact us today to discuss your requirements and explore how we can support your energy infrastructure.