12MVA 16MVA 20MVA 35 kV Transformer

Primary Voltage Ratings: 23/35kV
Secondary Voltage Ratings: 13.8kV
CONNECTION TYPE: Delta-Wye configuration
Standards: IEEE
Application: Oil & gas
Power Rating: 12MVA & 16MVA & 20MVA
Certificate: UL
Cooling Method: ONAN / ONAF-1 / ONAF-2

Designed specifically for mobile power solutions in the oil and gas sector. The transformer is a custom engineered 3 phase distribution transformer combined with mobility, capacity, and rugged performance in one package. Daelim engineers has designed and developed this oil type transformer in accordance with IEEE C57.12.00 standards and has UL listed E583815. Featuring multiple cooling mechanisms to optimize the transformer working as per load requirements. Transformer also features an NLTC with a high voltage side having five tap positions and a single low voltage side giving transformer voltage range of 13.8 KV to 35 KV and power capacity of 12 MVA to 20 MVA.

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Power Rating

The transformer is designed to operate for three different power ratings as per the electrical load requirements. This is especially necessary for the oil and gas field where work load depends on the nature of tasks being performed at the moment.

The transformer offers power rating of

12 MVA
16 MVA
20 MVA

Each power rating has its own specific voltage and current output. The 12 MVA here works as the baseline power rating and most transformer features like load losses and impedance are calculated on this base line.

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Voltage Rating

The transformer is equipped with standard high voltage and low voltage winding. The high voltage winding gives different voltage options for each of the power ratings and thus has three different current ratings too.

Winding	Voltage	Configuration	Current
HV	23/25/27/33/35 kV	Wye (grounded)	62.7 A (typical)
LV	13.8 kV	Delta	3000 A

The five voltage connection at high voltage winding enables the transformer to match the various grid conditions. This is an ideal feature of a transformer for mobile deployment across different regions.

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Transformer Key Features

Type	Oil Type Distribution Transformer	Cooling Class	ONAN / ONAF / ONAF-2
Tap Changer	No Load Tap Changer / Five Step	Manufacturing Standard	IEEE C57.12.00
Phase	3 Phase	UL Listed	E583815
Power Rating	12000 / 16000 / 20000 KVA at 55 C rise	Feet Altitude	3282 feet
Base MVA	12 MVA	Weight	60540 pounds
Primary Voltage	23,000 V GRDY / 13,280 V (line-to-neutral)	No load loss	14.15 KW
Secondary Voltage	480Y / 277 V	Rated load loss	27.39 KW
Frequency	60 Hz	Manufacturer	Daelim Transformers
High Voltage side	23000 to 35000 V	First Manufactured in	Feb-25
Low Voltage side	13800 V	Application	Mobile Trailer Mount for oil and gas fields
Impedance	5.33%	Vector Group	YNd1 (Delta-Wye configuration)
Core Construction	Core Type	Vector Group	YNd1 (Delta-Wye configuration)

Current output and Tap Changer Details

The transformer is featured with no load tap changer with five tap positions for high voltage winding to get five different combinations of electrical voltage and current for each power rating.

H (kVA)
Voltage (V)	Amps (12000 kVA)	Amps (16000 kVA)	Amps (20000 kVA)	Tap Position (POS.)	Connects
35,000	197.9	284	329.9	1	1 - 2
33,000	210	279.9	349.9	2	2 - 3
27,000	256.6	342.2	427.7	3	3 - 4
25,000	277.1	369.5	481.9	4	4 - 5
23,000	301.2	401.6	502	5	5 - 6
X (kVA)
Voltage (V)	Amps (12000 kVA)	Amps (16000 kVA)	Amps (20000 kVA)
13,800	502	689.4	836.7

Load Performance

The transformer is also featured with a strong thermal and electrical design with high current capabilities and stable voltage output. This ensures that the transformer is offering efficient energy conversion with low operational losses.

Parameter	Specification
No-Load Losses	14.15 kW
Load Losses at 85°C	27.59 kW
Insulation Level	BIL 95 kV (Primary), with surge protection design compliance
Temperature Rise	65°C average (typical)

12mva 16mva 20mva transformer transportation

Cooling & Fluid System

The transformer is designed with three different cooling systems in one single package. The transformer has ONAN, ONAF 1, and ONAF 2 cooling systems and each system is designed to remove waste heat when the transformer is working at a specific load.

Cooling Method	Rated Capacity
ONAN	12 MVA
ONAF-1	16 MVA
ONAF-2	20 MVA

The transformer is also equipped with a removable radiator to remove waste heat when the transformer is working at its maximum capacity. The transformer tank contains 1950 gallons of mineral oil at 25 degree centigrade for cooling and insulation purposes and also has a radiator that can contain 199 gallons of mineral oil at 25 degree centigrade. This cooling system is designed for the ambient operating temperature of 40 degree centigrade or 104 degree Fahrenheit.

Weight and Dimensions

Each part of the transformer is designed to have minimum weight without compromising quality so it can be installed on trailers and can be moved with ease. Weight of Transformer core, winding, tank and fittings, transformer oil and cooling system is mentioned below in pounds.

Component	Weight (lbs) / Volume
Core and Coils	33,730 lbs
Tank and Fittings	17,420 lbs
Removable Radiators	4,770 lbs
Mineral Oil in Tank at 25°C	1,950 gallons / 13,670 lbs
Mineral Oil in Radiators at 25°C	199 gallons / 1,500 lbs
Total Weight	68,350 lbs
Weight of Transport (with oil)	60,540 lbs
Rise or Fall per 10°C Temperature Change	0.76 in.

Applications

The transformer was specifically designed to be trailer mounted transformer for a temporary and mobile power applications including

Drilling rigs
Temporary field substations
Modular power distribution
Pipeline stations
Flare gas recovery systems

Each unit is designed for long term outdoor exposure and all types of dynamic load handling including transport resilience. This makes it ideal for oilfields, refineries, and for rapid deployment energy systems.

Advanced Engineering & Compliance

This transformer was not only designed and developed to meet specific criteria of electrical load but also was engineered to have specific features specially of dimensions to meet specific requirements.

Transformer has fixed height and width with tight clearance to meet USA trailer regulations.
Thermal airflow optimization for confined spaces
Noise control with vibration damping enclosure (optional)

This Transformer designed and developed by Daelim Transformers complies all international standards and has all safety features.

IEEE C57.12.00 Standard
UL Listed E583815
PCB Free at manufacture

Safety and Maintenance Guidelines

The secondary side of the CT must not be open circuit
Core ground bushing must be grounded
Before installation or operating, read the instructions carefully
Do not operate transformer when the reading of liquid level gauge is below the low point of the scale
Do not operate the de-energized tap changer with the transformer energized
Perform biannual inspection and thermal imaging
Conduct oil DGA (dissolved gas analysis) every 2 years

Why Choose Daelim

At Daelim we offer a complete one stop solution of electrical transformer design, manufacturing, installation, and after sale service. Our team of engineers with decades of experience can design electrical transformers for your custom needs.

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