A Magnetic Oil Guage (MOG) is a mechanical device that is used to indicate the level of the transformer oil in conservator tank or main tank of a transformer and sounds alarm for low oil level. It is very important part of transformer and installed at the bottom of the conservator tank.
Construction of Magnetic Oil Gauge (MOG)
A magnetic oil gauge(MOG) is consists of a float, bevel gear arrangement and a indicating dial. The dial has scale from empty to full and a pointer. A mercury switch and bevel gear are fixed with the pointer. When the pointer rotates, the alignment of the mercury switch also changes according to the angle of rotation of the pointer.
One ball type or drum type float is attached with a long float arm. One unit of bevel gear is fitted on the other side of the float arm. The other unit of the bevel gear is magnetically coupled with pointer and mercury switch arrangement. The bevel gear arrangement is positioned inside the conservator tank of transformer and dial. Pointer and mercury switch are positioned outside the conservator tank.
Working Principle of Magnetic Oil Gauge (MOG)
All oil-immersed transformers are provided a conservator of transformer for the expansion of transformer oil due to temperature rise. When transformer insulating oil is expanded, the oil level in the conservator tank moves up to the conservator tank. Again when transformer oil volume is reduced due to fall in oil temperature, the oil level in the conservator falls down. But it is essential to maintain a minimum oil level in the conservator tank of transformer even at lowest possible temperature.
A magnetic oil level indicator or magnetic oil gauge(i.e mog) is used to indicate the level of insulating oil in transformer. The position of the ball or drum type float goes up and down depending upon the oil level in the conservator and consequently the alignment of float arm changes. Consequently, the bevel gear rotates.
This movement of bevel gear is transmitted to the pointer outside the conservator as this pointer is magnetically coupled with the bevel gear. The pointer is also incorporated with the mercury switch. So, when transformer oil level in the conservator goes up and down, the pointer moves on the MOG dial to indicate the actual level of transformer oil in conservator tank.
As the alignment of mercury switch changes along with the pointer then, switch closes and actuates an audible alarm when pointer reaches near empty position on the dial of magnetic oil gauge.
Conclusion
Hope you have clearly understand about the magnetic oil gauge (MOG), it’s construction and working. Make sure to leave your opinion and suggestion about this post in the comment section below.