Manifestations and corrective measures for transformer errors

1. Table of diagnostics, causes and solutions to fix the dry transformer  error

Signal	The cause of the error	Solution
Low insulation resistance.	The coil is damp.	Clean with dry air and ventilation.
	Aging	Clean, contact to manufacturer.
The protective device automatically jumps when the power is turned on	The coil is shorted	Contact to manufacturer
	The regulator is not correct or the primary is not connected properly	Check the pressure regulator position and wiring the primary winding.
	The fuse burned or incorrect type	Replace the fuse. Choose the right load current
	Protective relays. The time/current setting is incorrect	Check load current /time setting
Wrong secondary voltage	The primary voltage is missing	Check the installation process again. Contact the electric company
	The pressure regulator is not properly positioned or the clamp or ECU (engine control unit) is loose	Return the pressure regulator to the correct position. Tighten ecu, clamp.
	Coil break	Contact the manufacturer.
Unbalanced secondary voltage	Ecu, the clamp is loose in one phase.	Check power supply line, review the installation process and contact the utility power company.
	The fuse has broken one phase	Replace the fuse
	Coil is breaked	Contact the manufacturer
	Low voltage installation part. Low voltage asymmetric load.	Review the low voltage installation process.
	Loss of a primary phase	Contact the utility power company
Transformer activates false during operation	Activation and warning are set up incorrectly.  The thermometer is not correct	Review settings and test Thermometer.
	Pt100 (Resistance Temperature Detectors) sensor error on measuring temperature or thermistor	Check sensor and thermistor
	Broken fuse	Replace the fuse Contact the manufacturer
	The time on the relay has been incorrect	Check the setting time
Overcurrent relay jump or high-voltage fuse fire during the operation	Secondary-party is short-circuit	Eliminate the cause of the problem
	The insulating material is punctured	Contact to manufacturer
Relay jump wrongly while operating	Transformer error	Contact to manufacturer
	Broken current transformer that supplies power to the relay	Check current transformer
The temperature was abnormally high	ventilation is not enough	Check the ventilation, add fans if needed
	Transformer overload	Reduce the load or replace higher capacity transformers
	Heat at the core	Clean the core and tighten it
	The cable is hot	Check the electric cable load current. Check cable layout and cable diameter again.
High Earthing voltage	Loss of single-phase earth conductor	Check earth conductor
Transformer sound	Excessive supply current. Loose terminal (COSSE), ecu or accessories.	Replace ecu, terminal (COSSE) or tighten.
	Pour sound from walls or obstructions.	Install soundproof panels. Install the transformer not parallel to the wall. Install the anti-vibration base under the transformer.
	The power supply frequency is low.	Contact the electric utility company
Fuming	Broken insulation	Contact the manufacturer. Apply transformer fire-fighting manuals

2. Table of diagnostics, causes and solutions to fix errors in oil transformers

Signal	The cause of the error	Solution
Low insulation resistance	Ground fault, lack of oil.	Contact to manufacturer
The secondary voltage is not stable	Lack of primary voltage	Review the installation process and contact the electrical company
	Pressure regulator has been displaced or ecu, terminal is incorrect or loose	Review the position of the pressure regulator and wiring
	The coil is broken	Contact to manufacturer
Secondary voltage is asymmetric	Single-phase fuse is fired	Replace the fuse
	Ecu and terminal are loose in one phase	Review wiring. Review construction and installation process and contact the electricity company
	Coil break	Contact to manufacturer
	Low-voltage installations make secondary voltages asymmetric	Check for low voltage installation
	There is no primary single-phase power	Contact the electric utility company
The overcurrent relay is activated	Problem inside the transformer	Contact the manufacturer
	Error of current transformer for relay	Check current variables
Fake activation during operation	Wrong warning and triggering setting. Defective thermometer	Check settings again. Check the heat meter.
	PT100 sensor error in oil transformer or thermistor temperature measurement	Check sensor and thermistor
	The relay time is set incorrectly	Reset the relay setting time
	Short circuit of secondary controller	Check to eliminate the cause of the problem
Temperature is abnormal on the thermometer during operation	Connector and terminal of transformer are hot	Clean the surface of the terminal, ecu and tighten.
	Cable is hot	The cable is smaller than the standard. Replace the cable
The coil temperature gauge, the top oil layer temperature meter emit a warning or cause a jump.	Insufficient heat dissipation. High ambient temperature	Check the radiator again. Install a fan if necessary
	Overload Transformer	Reduce the load or install a higher power transformer
	Oil temperature is too high	Reduce load
	water temperature is too high	Reduce load
	Poor circulation of oil, water or air	Check oil, water and air circulation again.
Excessive ground voltage	Loss of single-phase earth conductor	Check  earth conductor
Transformer sound	Cable voltage is higher than specified level. Loose core.	Reduce the supply voltage or change the voltage regulator position. Tighten the core.
	Rebound sound from a wall or barrier	Install the sound suppression plate. Place the transformer in a direction not parallel to the wall. Use vibration-damping rubber under the transformer.
	Low frequency	Contact the power company
Relay jump fail during operation	Short inside transformer	Contact to manufacturer
	Short current transformer for the relay	Testing current transformer again
Transformer temperature is high	Oil level is low	Open the oil level check valve
	Oil pump protection	Check the oil pump and protect the oil pump
Buchholz-gas relay alarm	The gas is hot	Reduce Transformer load. If the released gas is flammable, sample the gas using a dissolved gas analyzer. Report the transformer separation and contact the manufacturer.
	The released gas is colorless and odorless	If the released gas is not flammable. Reduce the load to continue operating and strengthen monitoring.
Relay jump	Arc to analyze the poles	Gas analysis using DGA gas analyzer. Contact the manufacturer.
	Oil level is low	Add more oil and fix the leak. Soldered only when the transformer is filled with oil or inert gas (nitrogen).
The oil indicator indicates that the oil level is too high or too low	Oil level is incorrect	Adjust the oil level. Seal leaks. The transformer should only be soldered when it is full of oil or inert gas (nitrogen).
The relay indicates incorrect oil pressure.	Deviation Oil/water pressure is less than 0.03 bar	Reduce water pressure, check valve, clean water circulation / cool.
Report a leak	Leaks in cooling.	Repair/replace cooling.
The protective pressure relay is high, the pressure regulator under load (OLTC) warns	Pressure increases in the pressurized elements under load	Check and repair the switching switch of the pressure regulator
The pressure regulator under the load slipped from the rungs	Switching operation is not performed well (stop at the intermediate position of the step changer)	Check the pressure regulator, interlock and actuator
Pressure relief device jumps	The pressure in the transformer increases dramatically	Analyse gas and contact to manufacturer
Gas leak warning	Pull the gas out	Analyze gas and contact to the manufacturer

3. Conclusion
Above, MBT gave some manifestations, causes, and ways to overcome some basic errors during the electrical transformer operation. Hopefully, the above knowledge will help our customers and partners to have the most overview, the most effective way to handle errors in the transformer.
 
To limit the problem of minor errors; To modify the maintenance process, and make transformers stable and long-term operation, individuals and businesses with demand for transformers should learn and choose a transformer company with a high reputation in the market.  
 

Transformer is the key product of Hanoi Electric Transformer Manufacture Joint Stock Company (MBT). Our company is proud to be a manufacturer and supplier of top quality transformers, electrical cabinets - power stations in Vietnam.  With more than 20 years of experience in research and production, together with highly qualified staff, modern equipment, and technology, the market has highly appreciated MBT company products and services.
 
With the business motto: "Quality nurture reliability", customers who come to MBT will always receive products with high quality, reasonable prices, fast delivery time and good warranty service. 
 
Contact now +84 913 006 538 for free consultation support and receive the most preferential transformer quotation.