The magnetic oil level gauges serve the purpose of visually indicating the oil level in a tank or in a
conservator of oil filled transformers.
This instrument is composed of a disc indicator (or a red pointer) behind a dial frame and a float linked to said indicator by means of a magnetic field of force.
The indicator disc is for one half enamelled white and, for the other half, red. Alternatively the colour
proportion visible through the dial glass indicates the respective level position, whilst the dial face is marked at minimum and maximum oil level and at level corresponding to 20°C and 85°C (on demand other markings are available).
The oil level indicator's float follows the oil level fluctuations thus causing a permanent magnet to be shifted in turn.
This last is connected, by means of a magnetic field of force, to another magnet located into the external part of the oil level indicator casing. The rotation of the internal magnet will cause, on its turn, the rotation of the external magnet which is integrally fitted to the disc indicator / red pointer. The magnetic joint consents to the two-colour disc / red pointer to be not immersed in the oil but separated from it by an oil tight partition which is cast integrally to the instrument's body.
When the conservator oil level is at its minimum there is visible within the dial only the red portion of the indicator disc, whilst an oil level increase will progressively bring into prominence the white portion of the indicator disc.
The gauge may be provided with one, two or four microswitches for signalling of minimum and/or and
maximum oil level.