Shell MIDEL
Shell MIDEL: Proven performance,3 ester transformer liquids
Shell MIDEL synthetic and natural ester transformer liquids are selected by utilities and transformer OEMs across the globe.
Shell MIDEL synthetic and natural ester transformer liquids are acknowledged for their excellent fire safety and environmental protection properties,1,2 and their ability to extend the life of transformer cellulose insulation.3
Is your transformer located in a fire or environmentally sensitive location? What would be the consequences of such an asset failing?
Shell MIDEL's properties drive installation savings5 as well as mitigate the risk of damage to life, property and the environment.1,2,4
This selection guide covers the key characteristics of three Shell MIDEL ester transformer liquids:
- Shell MIDEL 7131
- Shell MIDEL eN 1204
- Shell MIDEL eN 1215
The "eN" prefix denotes natural esters, which are formulated using renewable base oils from different seed crops, whereas Shell MIDEL 7131 is a synthetic ester liquid. All Shell MIDEL liquids are biodegradable.2
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High fire point - delivering critical fire safety, saving on fire protection costs.1
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Low pour point - our synthetic ester is the premier liquid for colder climates.3
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Biodegradable - protecting the environment and reducing containment costs.2
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High moisture tolerance - extending cellulose insulation life and reducing overall total cost of ownership.3
All Shell MIDEL ester liquids are approved by Factory Mutual (FM Global, less flammable fluids) and classified by Underwriters Laboratory (UL Classified).6
Why end users select Shell MIDEL
Your trusted adviser on ester transformer liquids
Our team of engineers, environmental chemists and technical experts are your go-to resource for selecting the right ester type for your specific application. Our experts regularly contribute to IEC, IEEE, ASTM and CIGRÉ working groups, playing a key role in the advancement of ester adoption. Every day, we provide technical advice to end users and transformer OEMs worldwide.
To understand more about how ester liquids can improve power or distribution transformer safety, performance or sustainability, we invite you to connect with our Shell MIDEL specialists.
All Shell MIDEL liquids are biodegradable and non-hazardous.2,4
Fire Safety
A high fire point significantly increases transformer fire safety, and mitigates risk and potential negative implications, such as:
- Downtime and lost production
- Network loss, blackout
- Increased insurance premiums
- Remediation and clean-up
- Asset repair and replacement costs
- Reputational damage
Minimum required clearances for an example transformer, fluid volume 2,000 - 19,000L8
Minimum required clearance for an FM Approved fire-safe fluid8 in an advanced transformer:
0.9 m, giving a potential substation footprint reduction3
Blast/fire-wall requirements are determined by insulation thermal classification.
Graphic illustrates the smaller required clearance of 1.5 metres between transformers using a K Class fluid, in comparison with a required clearance of 7.6 metres and the need for reinforced concrete blast walls for transformers using an O Class fluid.
K classification (IEC 61039) - reduces the need for fire-protection equipment and saves space.8
Better for the Environment
The greener choice. Biodegradable, non-toxic, noncarcinogenic, not harmful to aquatic life.
Reduced remediation. Readily biodegradable within 28 days.
Unparalleled Environmental Benefits
Circularity Synthetic Ester
By regenerating end-of-use MIDEL 7131 (Excellent oxidation stability) we have avoided:
- Incineration
- Landfill
- Conversion to bio-fuel
- Composting
Now a circular economy fluid (Cradle to Cradle)
Retrofilling with MIDEL
- Replacing mineral oil with MIDEL ester transformer fluid.
- Expedited solution vs time for purchasing new transformer.
- Straightforward, cost effective and proven.
- Underpinned by 40+ years of MIDEL retrofilling experience.
| DT/DP | kV | M&I Position | Retrofill |
| DT | < 33kV | No foreseen issues. | Yes |
| PT | 33-66kV | Review nameplate; evaluation recommended for helical winding designs, disc type windings, tap changers. | Yes |
| PT | 66-170kV | Verification of leads & winding assembly recommended, ideally including dielectric design. Possible modifications required. | Contact MIDEL technical team. |
| PT | > 170kV | Applications should be considered R&D projects, requiring detailed design review and possible modifications. | Contact MIDEL technical team. |
Which Shell MIDEL?
Shell MIDEL 7131
Shell MIDEL 7131 is specifically formulated to be a fire-safe,1 high-performance3 fluid providing all the benefits of ester technology.
It is the fluid of choice when the performance demands on the transformer are higher, especially if located in a cold climate (it has a pour point of -56°C)3 or when there is a risk of contact with air.3 Shell MIDEL 7131 is also ideal for transformers located indoors, outdoors or underground, and for hightemperature, breathing-type equipment.
It has a long track record in demanding applications such as wind turbines and rolling stock and is proven over 400 kV.3 Shell MIDEL 7131 meets the IEC 61099 and ASTM D8240 standards.
Shell MIDEL eN 1204
Shell MIDEL eN 1204 is bio-sourced from rapeseed/canola oil.7 It has a pour point of -31°C,3 making it a highly effective natural ester fluid for cooler climates. It also has good oxidation characteristics compared to soybean-based ester fluids.
Shell MIDEL eN 1215
Shell MIDEL eN 1215 is a bio-sourced soybean natural ester.7 This product is an efficient general-purpose fluid, ideal for a wide range of transformers located indoors or outdoors.
Like all natural ester transformer fluids, both Shell MIDEL eN 1204 and Shell MIDEL eN 1215 are best suited for use in non-breathing equipment. Shell MIDEL natural esters meet the IEC 62770, IEEE C57.147 and ASTM D6871 standards.
Global experience with ester fluids
With operations in the UK, America, Europe and Asia, Shell MIDEL's reputation as a trusted, global brand continues to grow. With further innovations under way, Shell MIDEL continues to spearhead the adoption and development of ester transformer fluids. Having built close working relationships with end users and the major transformer manufacturers, we provide exceptional levels of technical support and guidance.
Case Study: KiwiRail - Fire Risk Mitigation
KiwiRail identified fire as being an unacceptable risk with its onboard traction transformers.
- Identified MIDEL 7131 as the logical solution. K class fire safe fluid as well as being fully oxygen stable.
- Traction transformers must deal with variable loads and potentially high heat. MIDEL 7131 is the fluid of choice for this application in Europe
- The 18 transformers were retrofilled in two phases by PBA over a two year period.
Case Study: Glencore MIM - Transition to MIDEL 7131
George Fisher Underground. All DTs retrofilled with MIDEL 7131.
Enterprise Underground. 10 out of 70 DTs retrofilled with MIDEL 7131.
Mine Services. Standardising on MIDEL 7131:
- Retrofilling of Soy Ester DTs commencing early 2024
- Retrofilling of all above ground DTs (300 to 400)
- 132kV Power Tx now specified as MIDEL 7131.
- 132kV Soy ester Tx - investigation on whether possible to retrofill with MIDEL 7131.
References:
- Shell MIDEL fluids are classified as K Class, with high fire and flash points, and are less flammable. These properties can prevent a transformer fire and save the property, people and environment in its surroundings. FM Approved, UL classified.
- Shell MIDEL can be claimed as biodegradable according to OECD 2 301 test (product).
- Shell MIDEL customer transformer placements data and internal research. View properties table on page 6 of this brochure.
- Non-hazardous according to the CLP regulation and GHS guidance.
- May reduce insurance premiums due to proven fire safety and FM Approval. Potential reduction in fire barriers leading to cost reductions for construction and land space. Can reduce asset downtime related to fire issues and moisture ingress. Advice should not override countries' local legislation and laws.
- FM Global, an international insurance carrier, provides a certification mark called FM Approvals through its independent testing arm. Safety products must be tested and approved before they are sold to the public. Underwriters Laboratories, a non-profit testing facility headquartered in Northwood, Illinois, is one of the organisations responsible for testing and approving these types of products.
- Shell MIDEL eN 1204 and eN 1215 have 100% Biobased Carbon Content. Tested according to ASTM D6866-21 method. Reported results are accredited to ISO/IEC 17025:2017 Testing Accreditation PJLA #59423 standards and all chemistry was performed at Beta Analytic testing laboratory and counted in their accelerators in Miami, Florida, August 2021.
- FM Global Data Sheet 5-4 (July 2019), spacing based on fire clearances only. Advice should not override countries' local legislation and laws. Any recommendation or suggestion relating to the use, storage, handling or properties of the products supplied by Shell or any of its subsidiaries, either in sales and technical literature or in response to a specific enquiry or otherwise, is given in good faith but it is for the customer to satisfy itself of the suitability of the product for its own particular purposes and to ensure that the product is used correctly and safely in accordance with the manufacturer's written instructions. © Shell International Ltd.
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