MESSKO® MMK
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Reliable Oil Level Monitoring for Transformers
Monitor the oil level in your transformer conservator with a robust magnetic oil level indicator. The MESSKO® MMK is available in different flange distances such as 600 mm and 800 mm and is designed for reliable operation in new installations and retrofit applications.
How it works
A float with an integrated permanent magnet moves with the oil level inside a measuring tube. This movement is transmitted to an external display rail with magnetic flaps, which rotate by 180° depending on the fill level. The color indication changes depending on the filling level. The oil level can thus be read clearly from the outside without direct contact with the measuring medium.
Why this product
- Reliable oil level monitoring for transformers
- Works independently without external power supply
- Suitable for retrofit on existing DIN 42552 flange connections
- Clear and long-distance readable display via magnetic flaps
- Low-maintenance and durable design
Features
- Available with flange distances such as 600 mm and 800 mm*
- Flange Connection and measuring tube made of stainless steel
- Magnetic float with permanent magnet
- Display rail made of UV-resistant polycarbonate
- Operating temperature from -40 °C to +80 °C
- Mineral oil and Midel 7131 (alternative liquids on request*)
- Protection degree IP55 (optional IP65)
- Optional limit value contacts and 4–20 mA output available*
*Optional features available. Contact us for more information.
Available MESSKO® MMK Variants
| Specification | MMK – 600 mm | MMK – 800 mm |
|---|---|---|
| Flange distance | 600 mm | 800 mm |
| Flange Connection | V4A (AISI 316) stainless steel | |
| Measuring Tube | V4A (AISI 316) stainless steel | |
| Number limit switches | 1 | |
| Cable length | 8 m | |
| Operating temperature | −40 °C to +80 °C | |
| Measurement medium | Mineral oil and Midel 7131 (alternative liquids on request) | |
| Installation | DIN 42552 flange mounting (Form B) | |
| Analog output signal | ✗ | |
Legend
✗ = not included
Documents
| Name | Category | Date | File size | Download |
|---|---|---|---|---|
MESSKO® MMK. Oil level indicator |
Operating instruction | 08/2025 | 2.123 KB |
 |
|
MESSKO® MMK Magnetic oil level indicators |
Flyer | 06/2025 | 359 KB |
|
FAQ - Frequently Asked Questions
How does the MESSKO® MMK measure the oil level?
The device uses a float with an integrated permanent magnet inside a measurement tube. Depending on the oil level, the float moves vertically and actuates magnetic flaps on an external indicator rail, providing a clearly visible indication.
Does the MESSKO® MMK require an external power supply?
No, the device operates completely passively and does not require any external power supply for level indication.
Can the oil level signal be transmitted to control systems?
Yes, the device can be equipped with optional limit switches for threshold monitoring and a 4…20 mA transmitter for remote signal transmission.
What is the maximum operating pressure?
The MESSKO® MMK is designed for operation at pressures up to 1 bar.
Which media can be measured?
The device is designed for mineral oil and can also be used with alternative insulating liquids within the specified operating conditions.
How is the device installed?
Installation is carried out via flange connections according to DIN 42552 directly on the conservator. The design allows straightforward mounting and retrofit in existing transformer systems.
Is the device suitable for outdoor and harsh environments?
Yes, the indicator is designed with weather-resistant materials and is suitable for operation in a wide temperature range from −40 °C to +80 °C.
Does the MESSKO® MMK require maintenance?
The device is designed as a low-maintenance or maintenance-free system when operated within the specified conditions.
What measurement accuracy can be expected?
The typical measurement accuracy is approximately ±2 display elements based on the magnetic flap indication.
Problem with the installation? No problem at all!
Discover our how-to videos for many products.
Welcome to our how-to videos section, your ultimate guide to easy installation, commissioning and maintenance. Our videos provide you with clear and understandable instructions specifically designed to make it easier for you to use our products.
These videos complement our operating instructions and provide additional visual support for a seamless implementation of your projects. Take a look at our videos and make your life easier.
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Dissolved Gas Analysis (DGA)
Download the DGA Application Guide and protect your transformers from unexpected failures
Our free Application Guide provides information on how Dissolved Gas Analysis (DGA) can help detect transformer failures early.
Learn what problems are caused by gases in the transformer oil and how continuous monitoring of hydrogen, carbon monoxide and moisture using an online DGA sensor can help prevent costly transformer downtime.
With your newfound knowledge, you can improve your equipment monitoring and minimize the risk of downtime and costly repairs.
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