FAQs
Q: Who is responsible for manufacturing Midel transformer fluid?
A: Midel transformer fluid is manufactured by M&I Materials Limited in the UK.
Q: Who are M&I Materials Limited?
A: M&I Materials Limited is a strong global business that specialises in materials for industry and science. Please see www.mimaterials.com
Q: I am interested in learning more about Midel, what should I do next?
A: Please contact our expert sales team and they will endeavour to answer all of your questions. Tel: +44 (0)161 864 5422 or email: midelsales@mimaterials.com
Q: Can I order Midel online?
A: At present Midel is not available to buy online.
Q: What are the typical lead times for Midel?
A: Normally ex-stock. We always endeavour to satisfy customer requirements.
Q: What are the nett weights of the containers used to transport Midel?
A: Please see Delivery and Packaging
Q: Does M&I Materials provide guidance about the storage and handling of Midel?
A: Yes, please see Storage and Handling Guide
Q: What is Midel?
A: Midel is the brand name for the ester based dielectric fluid for transformers.
Q: What is an Ester?
A: In chemical terms an ester is derived from the reaction of an alcohol with acid. Esters also occur in nature in the form of seed oils.
Q: What are the differences between synthetic and natural esters?
A: Synthetic esters are manufactured by reacting selected acids and alcohols to tailor their properties to the application. Natural esters are derived directly from seed oils, their properties are dependant on the base oil used. The main operational difference is that synthetic esters are far more oxygen stable than natural esters and are therefore suitable for use in free-breathing applications, while natural esters are not.
Q: Are ester transformer fluids a proven technology?
A: Synthetics esters have been in use in transformers for over 30 years and have a proven track record in demanding applications such as traction transformers. Natural esters are a more recent development and have been available commercially since the late 1990's.
Q: Is Midel suitable for all transformer applications?
A: Midel has a long and success track record in the following applications:-
- distribution transformers in urban areas and buildings
- traction
- wind turbines
- power transformers up to 238 kV/ 135 MVA
- pole-type transformers
- thyristor cooling in power electronics
Q: Why should I use esters instead of traditional mineral oil transformer fluids?
A: Esters have a high fire point (>300°C) and are readily biodegradable. They offer enhanced safety whilst being more environmentally friendly. Esters are also far more moisture tolerant than mineral oil, improving cellulose lifetime and allowing extended operation in demanding ambient conditions.
Q: Is there technical information available about Midel?
A: Please visit the Library
Q: What are the Thermal Properties of Midel?
A: Please visit Thermal Properties
Q: How does Midel compare to other transformer fluids?
A: Please see Comparative Data
Q: Is Midel compatible with all materials?
A: Please see Materials Compatibility
Q: Does Midel contain corrosive sulphur?
A: Recently the transformer industry has reported the failure of multiple large units due to the presence of corrosive sulphur. Midel has been tested by independent laboratories to ASTM D1275 B, Standard Test Method for Corrosive Sulphur in Electrical Insulating Oils and IEC 62535, Insulating liquids - Test method for detection of potentially corrosive sulphur in used and unused insulating oil. It was found to be Non-Corrosive.
Q: Is Midel RoHS compliant?
A: Midel is RoHS compliant; it does not contain the flame retardants PBB and PBDE, nor is it formulated using lead, cadmium, mercury or hexavalent chromium. The concentrations of these heavy metal contents are all below 1ppm.
Q: Can DGA and Furan Analysis be performed on Midel?
A: Yes DGA can be performed on Midel. The key indicator gasses such as Actylene (arcing) and Hydrogen (PD) are still relevant to Midel. For diagnosing common faults the standard methods (Rogers' Ratio, Duval Triangle) are good guides. Care should be taken in borderline cases as the fault diagnosis boundaries are slightly different for esters, and for Midel the total amount of gas will be lower for the same fault level, when compared to mineral oil.
Q: Is there a safety datasheet for Midel?
A: Please see Safety Datasheet
Q: Why is Midel thought to be fire safe?
A: Midel has a high fire point and 100% fire safety record, see Fire Safety
Q: What is K-class classification?
A: K-class is defined by IEC61100. In order to achieve K-class classification a fluid must have a fire point in excess of 300°C.
Q: Which independent agencies have verified the fire safety of Midel?
A: FM Global (Factory Mutual), Allianz.
Q: Are there reduced requirements for fire protection when using Midel?
A: FM Global (Factory Mutual) allow transformers to be sited closer together and without fire walls. They state that there should be no need for further fire protection if an approved transformer and fluid are used.
Q: What is the relevance of CEN / TS 455 45 for traction transformers?
A: European Standards CEN / TS 455 45 require that only K Class fluids can be used on rolling stock.
Q: Why is Midel environmentally friendly?
A: Midel is readily biodegradable and classified as non-water hazardous, please see Environmental Protection
Q: What is meant by readily biodegradable?
A: Please see Environmental Protection
Q: What certification has Midel got to demonstrate that it is environmentally friendly?
A: Midel clearly passes the OECD 301 series test for ready biodegradability, and is classified as non-water hazardous (nwg) by the German Federal Department of the Environment, UBA (Umweltbundesamt). It also meets the Fully Biodegradable standard of IEC 61039.
Q: Can Midel transformers be installed without fluid containment?
A: This depends greatly on the local government in the area that you are installing the transformer. The German Federal Department of the Environment, UBA (Umweltbundesamt) has identified Midel as being non-water hazardous, which brings reduced requirements for containment. FM Global (Factory Mutual) has also increased the volume of fluid before containment is required from 1,940 litres to 10,000 litres where an approved biodegradable fluid such as Midel is used instead of mineral oil.
Q: What is meant by the term moisture tolerant?
A: Midel can absorb far more water than mineral oil before the electrical characteristics are compromised.
Q: How does moisture tolerance extend cellulose lifetime?
A: Reducing water content in the paper slows down the rate of depolymerisation. See Moisture Behaviour Datasheet
Q: Why is moisture tolerance an advantage in retrofilling?
A: It can bring transformers back into service which were previously too wet for mineral oil. Theory suggests that drying of very wet transformers can be speeded up with the use of ester fluids due to their ability to absorb more water.
Q: Is Midel suitable for use in high temperature compact transformers?
A: Yes Midel has been used for many years in compact traction transformers operating with high temperature insulation such as NOMEX®. Midel is also specified for use in compact wind turbine transformers which can operate with a top oil temperature of 120°C.
Q: What is the maximum operating temperature for Midel?
A: In a sealed system Midel can operate long term at temperatures of up to 130°C (top oil) and 150°C (winding hot spot). Temperatures above this may be possible depending on the application, please contact Midel Technical Support - mideltech@mimaterials.com
