magnetic gauge in the conservator tank of the
TRANSCRIPT
MAGNETIC OIL LEVEL GAUGE IN THE CONSERVATOR TANK OF THE TRANSFORMER
• BY
• JULIUS ALOWONLE
•
JULI
US
ALO
WO
NLE
MAGNETIC OIL GAUGE
JULI
US
ALO
WO
NLE
INTRODUCTION
Magnetic oil level gauge (MOG) or A liquid level indicator is provided to aid in the systematic inspection of the transformer under load. It consists of a float-arm inside the tank, an indicating pointer and a magnetic coupling between the two across a liquid-tight separation. The gauge may be furnished with SPDT (Single Pole Double Throw) alarm contacts to give a remote annunciation of low liquid level.
Magnetic oil level gauge-This is a mechanical device used to indicate the position of transformer insulating oil level in the conservator tank of a transformer.
JULI
US
ALO
WO
NLE
MAINLY PARTS
These parts are
• A float.
• Bevel gear arrangement (magnetic coupled linked to the pointer ).
• An indicating dial ( pointer movement by magnetic field ) incorporate with mercury switch.
JULI
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ALO
WO
NLE
OPERATION PRINCIPLES
•Float Bevel gear Indicating dial Mercury switch
• (Alarm)
Movement Gear rotation Movement
by oil level (magnetic coupled) by pointer
expansion
JULI
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ALO
WO
NLE
CONSTRUCTION
•A ball or drum type float is attached to the bevel gear which is magnetically coupled with the pointer. The movement of the float is associate with the rotation of the bevel gear and the pointer due to the rise and fall of the insulation oil in the transformer conservator tank.
•The magnetic field between the bevel gear and the pointer initiate the rotation of the pointer (clockwise or anti-clockwise)
•along the dial.
•The dial has a scale from EMPTY, ¼, ½, ¾, and FULL.
•The prescribed oil level at either 30 oC or 35 oC ambient temperature may also be indicated on the dial (filling level).
•The mercury switch is fixed with the pointer which when rotates ,the alignment of the mercury switch also changes to energized an alarm during empty indication.
JULI
US
ALO
WO
NLE
WORKING PRINCIPLE
Electrical power transformer is incorporated with conservator tank for expansion and reduction of insulation oil due to temperature rise and fall during it working time.
Power transformer s are provided with a magnetic oil level gauge. In the conservator tank, a light weight hollow ball or drum floats attached to the bevel gear arm. The position of the float goes up and down depending on the level of oil in the conservator tank. The bevel gear rotates and transmitted to the pointer outside the conservator tank , as this pointer is magnetically coupled with the bevel gear. The pointer is also incorporate with a mercury switch. When the pointer reaches empty on the dial of MOG, this switch closes and actuate an alarm for attention for topping up oil in the power transformer
JULI
US
ALO
WO
NLE
MAGNETIC OIL LEVEL GAUGE
JULI
US
ALO
WO
NLE
WHY TEMPERATURE DEGREE INDICATOR SHOWN ON MOG ?
• The oil levels are generally indicated on the MOG dial as ‘Empty’, 1/4, 1/2, 3/4 and ‘Full’. But in between these levels usually 300C temperature indication is also shown. This is because oil level in the conservator tank changes according to the ambient temperature. The hotter the temperature, the more will be the oil level in the conservator tank due to expansion and vice versa. So, as the oil level depends on the ambient temperature, we must have an indication to what level the oil is to be filled at a certain temperature. This is why the level is indicated in temperature degrees so that when the ambient temperature is same as the temperature indicated on that MOG dial, the oil level should reach that mark to ensure that the Transformer has sufficient oil level in the conservator.
JULI
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ALO
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ADVANTAGES
• Continuous oil level monitoring – with ease in reading at men height.
• Magnetic couplings ensures a reliable movement transmission between float arm and pointer avoiding leakages through conservator wall.
• Initiate alarm at EMPTY oil level.
• Adjustable value settings for switches at ambient temperature.
• No printings neither stickers on the view glass: temperature indication is directly marked on the plate behind the view glass.
• Modern technology MOG are equipped with data downloading device.
JULI
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LIMITATIONS
• MOG is not incorporated with tripping relay.
• MOG is used only for measuring oil level in the conservator tank.
• It is not a fault detecting device.
• MOG may loss is reading vision on aging transformer due weather changes.
JULI
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ALO
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REFERENCES
• PRINCIPLE OF POWER SYSTEM BY V.K. MEHTA.
• 33/11KV, 3X15MVA INJECTION SUBSTATION OGUDU, IKEJA ELECTRIC LAGOS.
• www.electrical4u.com
• www.wikipedia.org
JULI
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ALO
WO
NLE