Solution to Common Problems

• The Insulation Resistance of the Iron Core to the Ground is Zero 1. Possible Reasons:
  (1) Due to burrs, metal wires, and other metal foreign objects overlapping at both ends between the iron core and the clamp.
  (2) The insulation of the foot is damaged, causing the iron core to be connected to the foot.
  (3) Metal objects fell into the low-voltage coil, causing the pull plate to be connected to the iron core.
  2. Solution:
  Use a slender iron wire to clear the passage between the low-voltage coil and the iron core downwards. After confirming that there are no foreign objects inside the passage, check the insulation of the foot. If it still cannot be resolved, the following methods can be adopted:
  (1) Use a 500V shake table to continuously pressure to find the fault point.
  (2) Connect the ground wire end of the welding machine to the grounding plate and weld the foot (with a current of about 250A).
  
  
• The Insulation Resistance of the Core to the Ground is Low 1. Possible Reasons:
  Generally, it is caused by dampness, and after the insulation material becomes damp, the insulation resistance will decrease.
  2. Solution:
  (1) Place an iodine tungsten lamp under a low-voltage coil and bake continuously for 12 hours to increase the insulation resistance value.
  (2) Connect the temporary power supply, start the transformer fan, and continue to dry the transformer.
  
• Common Faults of Temperature Controller Operation

  
  

  The display does not light up after the power is turned on.
  Possible causes:
  The power cable is not connected properly, or the power supply is under voltage.
  Treatment Method:
  Check the input power.
  
  A phase is blinking "OP", and the fault indicator is on.
   Possible causes:
  (1) The phase or three-phase sensor is open.
  (2) The sensor is damaged.
   Treatment Method:
  (1) Tighten the sensor connector screws.
  (2) Replace the sensor.
  
  A phase is blinking" OH", and the fault indicator is on.
  Possible causes:
  The phase exceeds the upper limit of the measurement range, and the measurement circuit has a large contact resistance.
  Treatment Method:
  Eliminate line contact resistance.
  
  A phase flashes "OL", and the fault indicator is on
  Possible causes:
  The phase exceeds the lower limit of the measurement range, and the measurement circuit of the sensor has a short circuit.
  Treatment Method:
  Check the sensor measurement circuit.
  
  The temperature controller flashes "Er".
  Possible causes:

  The internal setting parameter is modified, or the sensor measurement circuit is short-circuited.
  Treatment Method:
  Check the sensor measurement loop or contact the manufacturer.
  
  When the fan temperature is not reached, the fan cools automatically.
  Possible causes:
  (1) The fan is in the manual startup state.
  (2) The fan timing starts and stop function takes effect.
  Treatment Method:
  (1) Press the △ key to turn off the fan.
  (2) It is a normal phenomenon.
  
  After manually starting the fan, do not turn it off manually.
  Possible causes:
  At this time, the measured temperature value is directly between the temperature of the self-starting and stopping fan.

  Treatment Method:
  This is a normal phenomenon.
  
  Three phase measurement temperature imbalances.
  Possible causes:
  Pt100 thermal resistance fixed depth is different.
  Treatment Method:
  Adjust the fixed thermal resistance.
  
  A fixed phase temperature value is displayed, and the maximum indicator is on.
  Possible causes:
  The temperature controller is in the maximum display state.
  Treatment Method:
  Press the △ key to switch to the three-phase circuit display state.
  
  The buzzer kept ringing.
  Possible causes:
  It's a normal phenomenon.
  Treatment Method:
  Press the △ key to turn off the buzzer.
  
  After entering the operation state of a function, I do not know how to proceed to the next step or exit the state.
  Treatment method:
  Press the "SET" key until it returns to the normal display state and exits the function operation state. When the parameter setting function exits, make sure that the overtemperature trip temperature value is not modified.

  
  

• Common Faults in Fan Operation Abnormal sound when starting and running.
  Possible causes:
  (1) Foreign bodies fall into the fan.
  (2) The fan blade axis is deformed or out of the fixed slot.
  (3) The fixing bolt is loose.
  Treatment Method:
  (1) Check and clear.
  (2) Reset the axis and replace it if it is serious.
  (3) Check and tighten the fixing bolts.
  
  The fan is powered on and doesn’t run.
   Possible causes:
  (1) Cable connections are faulty.
  (2) Fan capacitor damage.
  Treatment Method:
  (1) Check and connect the power cable.
  (2) Replace the capacitor.
  
  
• The Imbalance Rate of DC Resistance Exceeds the Standard When conducting handover tests, loose tap bolts or incorrect testing methods can cause the DC resistance imbalance rate to exceed the standard.
  Inspection Items:
  1. Is there any resin residue inside the coil tap?
  2. Whether the bolt connection is tight？ Especially the low-voltage copper bar connection bolts.
  3. Is there any paint or other foreign objects on the contact surface? For example, use sandpaper to polish the joint contact surface smooth.

  
  

• Abnormal Travel Switch A travel switch is a device that protects operators when a transformer is running with electricity. If the transformer is live, the contact of the travel switch should be immediately closed when any shell door is opened, so that the alarm circuit is connected and an alarm is triggered.
  

  1. Common Fault: 

  Doesn't alarm after opening the door or still alarms after closing the door.

  2. Possible Causes:

   Poor connection, fixation, or malfunction of the travel switch.

  3. Solution:

  (1) Check the wiring and wiring terminals to ensure good contact.
  (2) Replace the travel switch.
  (3) Check and tighten the positioning bolts.
  
• Burning Marks on the High Voltage Side Corner Copper Pipe The corner copper tube on the high-voltage side of the transformer has signs of erosion and the high-voltage coil has blackened areas. The blackened areas of the high-voltage coil should be carefully inspected, and the blackened areas should be scraped off with a blade. If the carbon black is removed and a red paint color is leaked, it indicates that the insulation inside the coil is not damaged. Determine whether the coil is short circuited by measuring the transformer ratio. If the transformer ratio is normal, it indicates that the fault is caused by external short circuit arcing or damage.
• Analysis of Noise Causes and Solutions Noise is an inherent characteristic of transformers during operation, and relevant national standards have strict sound level limits for it. With the continuous enhancement of people's environmental awareness, the requirements for transformer noise levels are becoming higher and higher. The generation of noise can be summarized into the following reference reasons:
   Voltage Issues
  1. Possible reasons:
  Excessive voltage can cause overexcitation of the transformer, resulting in increased and sharp noise, which directly and seriously affects the noise of the transformer.
  2. Judgment method:
  First, look at the low-voltage output voltage, not the voltmeter on the low-voltage cabinet, this voltmeter only serves as an indicator and should be measured using a more accurate multimeter.
  3. Solution:
  Place the tap changer in the appropriate position based on the output voltage on the low voltage side. On the premise of ensuring the quality of low-voltage power supply, try to increase the high-voltage tap connection (reduce the low-voltage output voltage) as much as possible to eliminate the overexcitation phenomenon of the transformer and reduce the noise of the transformer.
  Resonance Issues with Fans, Casings, and Other Components
  1. Possible reasons:
  The resonance of fans, casings, and other components can generate noise, which is generally mistaken for the noise of transformers.
  2. Judgment method:
  (1) Shell: Hold down the transformer shell and observe if the noise changes. If there is a change, it indicates that the shell has resonance Phenomena.
  (2) Fan: Use a dry long wooden stick to top the outer shell of each fan and observe whether the noise has changed. If there is a change, it indicates that the fan has resonance phenomenon.
  (3) Other components: Use a dry long wooden stick to top each component of the transformer (such as wheels, fan brackets, etc.), and observe if the noise changes. If any changes occur, it indicates that the components have resonance phenomenon.
  3. Solution:
  (1) Check if the casing is loose or deformed, thoroughly tighten the fastening screws of the casing, fix the sheet metal of the casing, and correct the deformed parts.
  (2) Check if the fan is loose, thoroughly tighten the fastening bolts of the fan, and place a small piece of rubber between the fan and the fan bracket to solve the vibration problem of the fan.
  (3) Check if other components of the transformer are loose and tighten thoroughly.
  

  Installation Issues

  1. Possible reasons:
  

  Poor installation can exacerbate transformer vibration and increase transformer noise.

  2. Judgment method:

  (1) The foundation of the transformer is not firm or flat (with hanging corners), or the transformer base plate is too thin.
  (2) Using channel steel to frame the transformer will increase noise.
  3. Solution:
  (1) The installation unit shall modify the original installation method.
  (2) Adding shockproof rubber pads under the transformer trolley can solve some of the noise.
  Impact of Installation Environment
  1. Possible reasons:
  The operating environment affects the noise of transformers, and unqualified environments can increase the noise of transformers by 3dB to 7dB.
  2. Judgment method:
  (1) The transformer room is large and spacious, with echoes.
  (2) The transformer is too close to the wall, with a distance of less than 1 meter.
  (3) The transformer is placed at the corner, and the reflected noise on the wall overlaps with the transformer noise, increasing the noise.
  3. Solution:
  Indoor sound-absorbing materials can be added appropriately.
  

  The Vibration Problem of Busbar Bridge

  1. Possible reasons:
  Due to the large current passing through the low voltage connecting busbar, the busbar vibrates due to the leakage magnetic field. The vibration of the busbar bridge can seriously affect the noise of the transformer, increasing the noise by more than 15dB. This phenomenon is difficult to determine and is generally mistaken for the noise of the transformer.
  2. Judgment method:
  (1) The noise varies with the size of the load.
  (2) Use a wooden stick to firmly press down on the busbar bridge. If the noise changes, it is considered that the busbar bridge is resonating.
  (3) The busbar vibrates inside the bridge, and it is useless to use a wooden rod to support it. It is necessary to open the cover plate of the busbar bridge and check whether the busbar is fixed properly.
  3. Solution:
  (1) It mainly damages the resonance conditions of the busbar bridge, such as tightening or loosening the suspension rod screws.
  (2) Open the cover plate of the busbar bridge and secure the busbar.
  (3) Use soft connections for low-voltage outgoing lines.
  (4) Feedback to the manufacturer of the bus tray for on-site inspection and handling.
  

   Resonance Problem of Transformer Core Itself

  1. Possible reasons:
  The electromagnetic attraction generated by magnetic leakage between the joints of silicon steel sheets and the laminations.
  2. Judgment method:
  (1) The noise of the transformer is relatively high, and normal noise is mixed with other noises.
  

  (2) The noise of the transformer is wavy.

  3. Solution:

  (1) Tighten the screws on the transformer, including the two end screws of the clamp and the compression screw of the cushion block.
  (2) Add shockproof rubber pads under the transformer trolley.
   Resonance Problem of Transformer Coil Itself
  1. Possible reasons:
  When there is load current passing through the winding, the leakage magnetic field generated by the load current causes vibration of the winding.
  2. Judgment method:
  (1) The noise of the transformer is relatively loud, and the sound is relatively low.
  (2) When the load of the transformer reaches a certain value, noise begins to appear, sometimes without any phenomenon.
  3. Solution:
  (1) Tighten all the screws on the cushion block to increase the axial compression force of the coil.
  (2) Loosen all the screws on the cushion block screws, and loosen all the bolts on the outgoing and zero copper bars
  Shake the low-voltage coil, shift the high-voltage coil by 3-5 millimeters, and then tighten all bolts.
  Load Issues
  1. Possible reasons:
  

  The voltage waveform of the transformer undergoes distortion (such as resonance caused by higher-order harmonics), resulting in noise.

  2. Judgment method:

  (1) In addition to the noise of the transformer itself, there is also a mix of "clucking" noise in the noise.
  (2) During operation, there will be a sudden increase in noise, which will soon return to normal.
  (3) Check if there are rectification equipment and frequency conversion equipment in the load.
  3. Solution:
  Consider installing devices to reduce harmonics.
  Transformer Phase Loss Problem
  1. Possible reasons:
  The transformer cannot excite normally and generates noise.
  2. Judgment method:
  (1) After the power outage of the transformer, check if the power supply is out of phase.
  (2) Check if the high-voltage fuse of the transformer is blown.
  3. Solution:
  (1) Immediately contact the power department and take recovery measures.
  (2) Replace the fuse.
   Poor Contact Issues
  1. Possible reasons:
  (1) Poor contact inside the high-voltage cabinet.
  (2) The knife switch is not fully closed.
  2. Judgment Method:
  The transformer emits intermittent and abnormal noise.
  3. Solution:
  (1) Check the contacts and fuses of the high-voltage cabinet, as well as the entire high-voltage circuit.
  (2) Feedback to the manufacturer of the high-voltage cabinet for on-site inspection and handling.
   Suspension Potential Issue
  1. Possible reasons:
  The poor contact of the clamping channel steel, pressure nail bolts, pull plates and other components of the transformer generates floating potential discharge and sounds between the components under the action of the leakage magnetic field.
  2. Solution:
  During power outage maintenance, scrape off paint from areas that are not in good contact to ensure good contact between various components.
  
  
• Abnormal Transformer Sound During Power Transmission The sound of the transformer during power transmission varies from high to low. If the sound is loud (only in the case of vibration sound), there are several possibilities:
  1. Noise caused by loose bolts on the casing (pay special attention to the bottom mesh).
  2. The output voltage is too high (about 420V), which can be solved by adjusting the tap position, such as 428V. Adjust the high voltage tap position upwards and place it in the 10500V range (10 ± 2 × Taking 2.5%/0.4 as an example, that is, 2-3 tapping positions (before adjusting the tapping position, one end of the copper wire is grounded, and the other end is placed in the exposed copper part of the high-voltage connecting cable for discharge, and then the tapping position is adjusted).
  3. There are foreign objects (small bolts, nails, etc.) inside the fan.
  
• Discharge Between The Shell and The Ground Iron Plate During Power Transmission This phenomenon occurs during power transmission, indicating that the conductivity between the shell and the grounding iron plate is not good enough and the grounding is poor. A 2500M Ω meter can be used to determine the discharge position on the surface of the iron plate. After removing the paint film from the discharge position on the surface of the iron plate and the connection position on the shell, it is connected with copper wire and then grounded to the grounding grid.
  
• Transformer Temperature Rise Exceeding Standard When the temperature rise of the transformer exceeds the specified value, the following steps should be followed for inspection and handling:
  
  1. When both temperature control and temperature display devices are installed, their temperature display values can be read separately to determine the correctness of the temperature measurement device.
  
  2. Check the operating load of the transformer and the temperature of each winding and ensure that it is under the same load conditions as in the operating records compare and verify the normal temperature of.
  
  3. Check the ventilation of the transformer cooling device or transformer room. When the reason for the temperature increase is due to wind. When the cooling device malfunctions, the operating load of the transformer can be lowered to reduce the temperature of the transformer.
  
  4. Under normal load and air-cooled conditions, the temperature of the transformer is abnormal and continuously rising, and temperature measurement has been proven.
  When the indicated value of the device is correct and it is believed that the transformer has internal faults, it should be immediately shut down.
  
  5. When the transformer operates beyond the rated current on the nameplate and the temperature rise exceeds the maximum allowable value, the load should be immediately reduced.