How To Install And Use A Single-phase Oil-immersed Tap Changer?

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 Here are the detailed usage instructions and installation points for single-phase oil-immersed rotary tap changer:

 How to use single-phase oil-immersed rotary  tap changer (operation procedure)

Since it is an excitation-free switch, the core prerequisite for operation is to cut off the power supply of the transformer. The specific steps are as follows:

1. Cut off the power supply and discharge (Safety First)

* Confirm that the transformer has been disconnected from the power grid and is in a completely powered-off state.

* Perform reliable grounding discharge on the high-voltage and low-voltage sides of the transformer to ensure that the equipment has no residual charges.

2. Confirm the current position

* Check the mechanical indicator on the top of the switch (usually a pointer disk or digital window), and record the current position number (such as “3″ position).

3. Manual operation

* Locate the operation handle interface on the top of the switch (usually a square or hexagonal shaft).

* Insert the dedicated operation handle (usually provided with the equipment).

* Rotate the handle clockwise or counterclockwise. When you hear a clear “click” sound (ratchet positioning sound), it indicates that you have switched to a new position.

* Note the direction: usually clockwise rotation (RAISE) for voltage increase, counterclockwise rotation (LOWER) for voltage decrease. The specific direction should be referred to the arrow markings or nameplate instructions on the switch body.

4. Confirm the target position

* After rotating to the desired position, confirm again that the position indicated by the mechanical indicator is correct.

* Pull out the handle and cover the dust cover.

5. Check before restoring power

* After the operation is completed, a DC resistance test must be performed (very important!) .

Use an ohmmeter or micro-ohmmeter to measure the DC resistance of the transformer windings. Verify that the resistance value of the new step is consistent with the factory value or historical data, and ensure three-phase balance (if it is a three-phase transformer).

If the resistance value is abnormal (such as infinity or short circuit), it indicates that the switch contacts are not properly connected or the connection is incorrect. Do not energize the circuit; instead, recheck the connection.

II. Installation Steps and Precautions

This product is usually installed as a component of the transformer in the factory. However, when replacing or repairing on-site, the following steps must be followed:

1. Installation environment check

* Ensure the transformer oil level is normal and the oil quality is clean.

* Check if the sealing surface of the installation flange is flat and free of scratches.

2. Sealing treatment (oil leakage prevention)

* Clean the bottom of the switch and the sealing surface of the transformer flange.

* Place the O-ring correctly in the sealing groove to ensure it is not distorted or damaged. This is the key to preventing oil leakage from the transformer.

3. Alignment and fixation

* Slowly insert the switch into the installation opening of the transformer oil tank.

* Pay attention to aligning the direction of the drive shaft (usually there are triangular marks for alignment), ensuring that the operating mechanism can be properly connected.

* Use bolts to evenly tighten, with the torque meeting the manufacturer’s requirements to prevent seal failure due to uneven force.

4. Operating mechanism connection

* Connect the vertical transmission shaft or gearbox.

* Manually operate several cycles to check if the rotation is flexible and there is no jamming.

5. Oil filling and exhaust

* If the switch has an independent oil chamber (for some models), it needs to be filled with insulating oil separately.

* Open the top vent plug and let oil overflow until there is no air remaining inside.

III. Key Safety Warnings

1. Prohibition of Electrical Operation: This switch does not have arc extinguishing capability. If the gear position is switched while the transformer is energized, a huge arc will be generated, causing the switch to explode, the transformer to burn out, and even resulting in personal injury.

2. Avoid Over-positioning: When manually rotating, be careful not to exert excessive force and exceed the maximum or minimum gear position (dead gear). Otherwise, the internal gear mechanism will be damaged.

3. Regular Maintenance: Although this is an unexcited switch, the contacts may oxidize after long-term operation. It is recommended to check the contact resistance and wear condition of the contacts in combination with the transformer maintenance cycle.

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