MIDEL eN
Natural Ester
Transformer Fluid
Product Guide
Experience: The Difference
MIDEL eN – Reducing Risk
MIDEL eN
MIDEL eN is our natural ester-based
dielectric fluid which is suitable for sealed
electrical equipment or equipment fitted
with a bagged conservator. In particular it
is ideal for installations in temperate
locations or indoors.
Natural esters or vegetable oils as they can also be
known, are a group of materials which are directly
derived from renewable plant sources. In the case of
MIDEL eN the source material is rapeseed oil.
Since their introduction in the 1990’s natural esters have
primarily been used in distribution transformers.
Nowadays natural esters are successfully being applied
to large power transformers.
MIDEL eN is an excellent dielectric fluid because it has a
high fire point making it far more fire safe than mineral
oil. It is also one of the most environmentally friendly
dielectric fluids available. Not only is MIDEL eN
manufactured using renewable vegetable oil, it is also
non-toxic and readily biodegradable.
In addition, MIDEL eN offers superior moisture tolerance
and it has the potential to increase the lifetime of
cellulose based solid insulation, which in turn can extend
the life of the transformer.
M&I Materials Ltd
Our multilingual sales and customer service personnel
and internationally recognised team of highly
experienced engineers and chemists are always ready to
offer their expert guidance and ongoing support.
MIDEL eN
Experience: Safety
M&I Materials Ltd is the driving force behind the
success of Midel fluids. Our Midel team
specialise in transformer fluids and have many
years experience in manufacturing synthetic and
natural esters. Our Midel plant is dedicated
exclusively to the production of esters for the
electrical industry and we are very proud of our
reputation.
Our experienced engineers and chemists have
built close working relationships with the major
transformer manufacturers. They are also
respected leaders of CIGRÉ and IEC working
groups and regularly undertake extensive
projects with prestigious research organisations.
We believe our breadth of experience allows us
to provide an unrivalled standard of expert
technical guidance.
M&I Materials
Experience: The Difference
Midel is the world’s leading brand of ester-based
dielectric fluids primarily because of its excellent track
record and ability to minimise risk. However, we also
maintain this position because of our commitment to
supporting our customers both technically and
commercially.
Distribution
Increased Fire Safety
100% fire safety record
High fire point (>300°C)
K-class classification
Suitable for indoor and outdoor installation
FM Global® and UL® listed transformer fluid
Established resistance to ignition
Reduced protection costs
Potentially lower insurance premiums
High Performance and Low Maintenance
Suitable for use in hybrid and aramid designs
Allows for compact transformer design
Excellent lubrication properties
Self healing
Lower no-load losses than cast resin transformers
No corrosive sulphur
No sludge formation
Greater Environmental Protection
Renewable vegetable oil
Lower carbon footprint than mineral oil
Readily / fully biodegradable
Non-water hazardous
Non-toxic and not harmful to aquatic life
Will not evaporate into the environment
Not detrimental to degradation of activated sludge in
biological treatment plants
RoHS compliant
Power
Superior Moisture Tolerance
Absorbs large amounts of moisture with no reduction
of breakdown voltage (up to 300ppm)
Allows moisture to migrate from cellulose into the
fluid
Very high saturation limit making precipitation of free
water virtually impossible
Reduces the risk of bubble formation
Asset Life Extension
Slower rate of cellulose ageing than mineral oil
Longer lifetime at standard temperatures
Option to run at a higher temperature, for a standard
lifetime
Provides a higher power output, without the need for
high temperature insulation
Has the potential to offer smaller, lighter
transformers with cellulose
Today in modern distribution and transmission
networks there is a focus on total life
management. The new ISO 55 000 suite of
standards for asset management brings with it a
need to get the most from equipment.
As part of a whole life strategy for transformers
MIDEL eN offers an effective solution to reduce
installation costs due to its fire and
environmental properties. It also offers extended
lifetime for transformers, which can substantially
reduce overall lifetime costs. Alternatively there
is the potential to produce smaller transformers
which use far less raw materials than mineral oil.
MIDEL eN is manufactured using
renewable vegetable oil and is readily
biodegradable making it the most
environmentally friendly dielectric fluid
on the market.
www.midel.com
Distribution
Power
Comparison of Transformer Fluids
Fire Safety Class
MIDEL eN
Mineral Oil
Silicone Liquid
K2
O
K3
X
X
Readily / Fully Biodegradable
Water Hazard Classification
nwg
1
1
Breakdown Voltage kV
>75
>70
50
1100
55
220
37
12
39
0.92
0.88
0.96
0.00074
0.00075
0.00104
Permittivity
3.1
2.2
2.7
Pour Point °C
-31
<-50
-50
Good
Poor
Excellent
Moisture Saturation ppm at Amb Temperature
Kinematic Viscosity at 40°C
Density at 20°C
Expansion Coefficient
High Temperature
Data quoted above are typical values, may be altered without notice and do not constitute a specification
Detailed technical data is available on request, via scanning the
QR code or from our website
Contact our team today to discuss your project requirements
Tel: +44 (0)161 864 5422
E-mail: midelsales@mimaterials.com
www.midel.com
MIDEL eN - Asset Life Extension
Midel fluids can have a beneficial influence on paper
ageing, this gives
As part of the new standards a unit life vs. temperature
chart has been produced for both kraft paper and
thermally upgraded paper. This summarises the
findings of a large number of studies conducted with
natural ester fluids and indicates that at an operating
temperature of 95°C the lifetime for kraft paper could be
as much as 5 times longer than in mineral oil.
Alternatively to get more power from the transformer,
without additional loss of life, the ester unit life chart
indicates that kraft paper can be run 16°C hotter.
Longer life for cellulose insulation at standard
temperatures
The option to run transformers at a higher
temperature for standard lifetime
The benefit of a higher power output or a smaller
footprint by running transformers hotter.
Researchers around the world have determined that
immersion in natural ester based transformer fluids
offers longer lifetime for cellulose insulating paper than
mineral oil. Following years of painstaking
investigations this research has been summarised
within IEC 60076-14:20131 and IEEE C57 154:20122, with
information provided on the potential life extension.
In the case of thermally upgraded paper the lifetime
extension can be as much as 7 times, or alternatively
the running temperature can be increased by 20°C if
ester is used in place of mineral oil. Whichever type of
insulating paper is chosen this gives asset managers
more flexibility and could substantially cut lifetime
costs.
1. IEC 60076-14 ed1.0 (September 2013) Power transformers - Part 14: Liquid-immersed power transformers using high-temperature insulation materials
2. IEEE C57.154 (October 2012) Standard for the Design, Testing, and Application of Liquid-Immersed Distribution, Power,and Regulating
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Any recommendation or suggestion relating to the use, storage, handling or properties of the products supplied by M&I Materials Ltd 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.
© M&I Materials Ltd. October 2014
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