Technical Information

Møre Trafo AS only produces oil-immersed transformers. Oil transformers typically have lower losses, lower noise levels, and higher operational reliability compared to dry-type transformers.

Production Capacity

• Output: From 10 kVA single-phase to 4000 kVA three-phase
• Frequency: 50 Hz, 60 Hz and 16.67 Hz
• Voltage: From 120 V to 36 kV
• Insulation level: 1.1 kV AC 3 kV, 3.6 kV AC 10 kV LI 20 kV, 12 kV AC 28 kV LI 75 kV, 24 kV AC 50 kV LI 125 kV and 36 kV AC 70 kV LI 170 kV
• Winding configuration: 2- and 3-winding transformers, autotransformers, earthing transformers, etc.
• Vector groups: All conventional vector groups and phase sequences (Dyn, Yyn, Yzn, Dd, Yd, ZNyn, etc.)

Special Projects

• Transformers with multiple voltage taps and windings for test labs or special industrial applications
• Automatic voltage-regulating distribution transformers (IEC 60076-24)
• Special voltages for pumps, motors and internal distribution networks (e.g. 690 V, 1000 V, 3300 V, 5250 V, 10 500 V)
• Deliveries for marine, offshore and construction with strict environmental or fire requirements

Foils and varnish or paper-insulated wire in copper or aluminum. All paper insulation is thermally upgraded type (TUP).

Mineral oil or esters (for high temperatures). Møre Trafo has long experience with natural esters (environmental oil) for applications with high fire and/or environmental requirements.

Natural Ester Oil FR3

Transformers can be supplied with Envirotemp FR3, a high-quality, biodegradable oil based on natural ester (vegetable fat). The oil is clear, odorless, light green and approved for environmentally friendly use, and breaks down by more than 99% in under 28 days if it leaks into nature.

Benefits

• High dielectric constant (≈3.2) that reduces insulation stress compared to mineral oil (≈2.2)
• FR3 absorbs significantly more water (up to 425 ppm at low temperatures) than mineral oil and actively works as a drying medium. This results in a 5–8 times longer service life for the paper section.
• Transformers filled with FR3 can operate up to 20°C higher without reduced safety, giving 20% higher load capacity
• Envirotemp FR3 has a flash point of 330°C and a fire point of 360°C, about twice as high as mineral oil (155°C and 165°C)
• FR3 is non-toxic and contains no petroleum-based components. Spilled oil needs minimal cleanup

Viscosity

• According to NEK 2401 (2001), insulating oil at −30°C must have a viscosity ≤ 800 cSt
• You can use Envirotemp FR3 at −20°C, even though it is gel-like at that temperature, without damaging the insulation
• At 40°C the viscosity is about 34 cSt
• At 100°C only about 8 cSt

Conventional 105 (A) (IEC 60076-1) or 120 (E) and 130 (B) for more compact designs (IEC 60076-14).

Dial thermometer with alarm function

An analog dial thermometer monitors the oil temperature in the transformer. The thermometer has 4 indicator needles: red = highest temperature reached (resettable), white = current temperature, blue = alarm temperature, yellow = trip temperature. Accuracy ± 3°C.

PT100 temperature sensor

PT100 is an accurate temperature sensor used to monitor temperature in transformers. The PT100 sensor is a platinum-based resistance thermometer that changes resistance value with temperature. At 0°C it has a nominal resistance of 100 Ω.

Powder-coated C4 (medium) or hot-dip galvanized C4 (High).

Enhanced Protection

Møre Trafo has developed solutions that meet the regulatory requirements in FEF 2006 and the standard requirements in NEK 440:2011 for transformers with enhanced protection. This solution makes it possible to install oil-immersed transformers with a high level of safety close to buildings.

When the transformers are tested and equipped according to the concept of enhanced protection, you can reduce the distance to the building from 5 meters to 1 meter.

The insulating liquid must be routed down into an oil collection tray and away from the control panel and people. Enhanced protection requires K‑class insulating liquid (flash point >300°C), for example Miljøolje or Natural Ester FR3.

Pressure Relief Valve

Since 2023, Møre Trafo has used a new model of pressure relief valve with both a mechanical warning indicator and electrical signal contacts. At the preset pressure, the pressure relief unit opens, reduces the pressure, and then closes tightly again when the pressure has dropped.

All power transformers sold in Europe must meet the requirements in EU Regulation EU 548/2014 with amendment EU 2019/1783.

Distribution Transformers (≤3150 kVA)

For distribution transformers and smaller power transformers ≤3150 kVA, the regulation sets absolute limits for maximum no-load losses (Po) and load losses (Pk). These maximum limits, including exceptions and corrections, are specified in the regulations and in EN 50708-2-1.

Power Transformers (>3150 kVA)

For power transformers >3150 kVA there are absolute requirements for minimum efficiency, specified by PEI (Peak Efficiency Index). You can find the limits in the regulation and in EN 50708-2-1.

IEC 60076 series

• IEC 60076-1: General requirements for power transformers
• IEC 60076-6: Reactors and earthing transformers
• IEC 60076-14: High-temperature insulation materials
• IEC 60076-24: On-load tap-changing distribution transformers

European standards

• EN 50708-1: General requirements with European additions
• EN 50708-2-1: Efficiency requirements for distribution transformers
• EN 50708-2-2 to 2-4: Regulating distribution transformers
• EN 61238-1: Class A certification for 2D clamps

Norwegian Standards

• NEK 2401: Oil Specifications for Transformers
• NEK 440: Requirements for enhanced protection
• NEK EN 61936-1: Substations Above 1 kV

Simple tap changer

Most transformers come with a simple tap changer with 5 or 7 steps. Step 1 corresponds to the highest high-voltage (HV), while the last step gives the lowest HV voltage.

The tap changer sits on the high-voltage side and adjusts the transformer’s output voltage to match the local grid voltage.

DETC (De-Energized Tap Changer)

Tap changers are mainly supplied as DETC with 5 or 7 steps, typically ±2×2.5% or +2−4×2.5% on the HV side. Other regulation ranges are available on request.

Automatic on-load tap-changer (MR ECOTAP)

Automatic on-load tap changer with 9 or 17 steps for, for example, automatically regulated distribution transformers is available on request.

Reconfigurable High-Voltage

Some transformers can switch between two different high-voltage levels in addition to the tap changer. These have two positions marked with Roman numerals I and II. Position I indicates the highest voltage and position II the lowest voltage.

Reconfigurable Low-Voltage

Some transformers have taps at both the start and end of the low-voltage winding so you can switch between star (Y) and delta (Δ), giving two different output voltages – typically 415 V and 240 V.

• Y-delta (Dyn11): Delivers 415 V output voltage and a +30° phase shift, with neutral point available. Ideal for distribution grids.
• Delta-delta (Dd0): Delivers 240 V with no phase shift. Common in industrial installations.

Vector Groups

We deliver a wide range of vector groups tailored to different grids and needs. Dyn11 is the most common, but other groups such as Yyn0, Yd5, Yd11, Dd0 and more are available on request.