Installing oil lines - OPT100

OPT100 Installation Guide

Document code
Document type
User guide
  • Adapters for connecting the oil pipes to the valves on the transformer
  • Adapters for connecting the oil pipes to the DGA monitor, if not using the recommended tubing size (10‑mm (0.39‑in) outer diameter). Optional accessories for connecting 3/8" and 1/4" outer diameter tubing are available from Vaisala.

  • Recommended oil pipe material: stainless steel tubing with 10‑mm (0.39‑in) outer diameter. Reserve enough pipe material to connect the oil intake and return valves to the DGA monitor.
  • Pipe fittings for joining pipe sections
  • Pipe supports
  • Pipe bending tool
  • Pipe cutting tool
  • Pipe deburring tool
  • Pressurized air, either a bottle or a compressor
  • Wrenches of various sizes
  • Container for waste oil with at least 5 liter (1.3 gallon) capacity
  • Oil pipe insulation, for example ArmaFlex tubing (min. 20-mm (0.787 in) wall thickness) (recommended in cold climates, especially for devices using synthetic ester liquid)
  • Trace heating, self-regulating, 10 W/m (recommended in cold climates, especially for devices using synthetic ester liquid)
  • Transformer valve tag (2 pcs)

When working with oil pipes, hoses, fittings, and adapters:

  • Keep parts and tools clean and off the ground. Dirty parts may contaminate the transformer oil or cause connections to leak.
  • Oil pipes, hoses and connection adapters must be dry, without any free water residue inside. Water inside the oil lines can cause issues with the OPT100 measurement and water may be carried with the oil to the connected transformer.
  • Use new Swagelok® adapters (nuts and ferrules) when making new connections. Do not use third party adapters or used parts from a different connection. Opening and retightening existing oil line connections without changing the nuts and ferrules is OK as long as the parts appear intact and you can verify the connections do not leak. Swagelok part code for the included 10-mm pipe adapters is SS-10M0-NFSET.
  • If you are unsure about the proper use of fittings and adapters, refer to their manufacturer's instructions online.

If the DGA monitor is mounted using the wall mounting set, the power supply unit will be attached by a mounting cradle. Make sure you are not routing the oil lines so that they will obstruct the power supply unit attachment.

Wear protective eyewear and gloves.

Before starting to install the oil lines, see installation site requirements and recommended locations of oil connections for important information.

  1. Inspect and prepare the selected inlet and outlet oil valves on the transformer:
    1. Remove any previously installed flow direction control valves. The DGA monitor needs to pump oil in both directions during initialization, and will not work if there are flow direction controllers in the oil lines.
    2. Clean any loose dirt from the outside and inside of the oil valves on the transformer.
    3. Drain some oil from the selected valves into the waste oil container. Verify that the oil is clean and there is no sludge coming out with the oil. If there is sludge, do not use that valve to connect the DGA monitor.
  2. Install the adapters to the inlet and outlet valves on the transformer to match them to the size of the oil pipe material.
  3. Measure the distance from the oil valves to the DGA monitor, and plan the length and shape of the oil pipe sections. Minimize the amount of joints.

    Make sure that both oil connections on the transformer are below oil level. There must be no risk of drawing gas into the oil lines even when the flow is reversed.

  4. Make sure the pipes are dry from the inside. If there are traces of water, blow compressed air through the pipes to remove the water.
  5. Cut and bend the oil pipe to appropriate sections for building the oil lines.
  6. Remove any sharp edges from the cut surfaces.
  7. Clean any metal shavings from inside the pipes using pressurized air.
  8. Build the oil lines between the valves and the oil connections on the DGA monitor marked Oil In and Oil Out.
  9. Remove the plugs from the pipe fittings on the DGA monitor and store them for possible later use. Check that the fittings are clean.
  10. Connect both oil lines to the fittings on the DGA monitor. Use the supplied Swagelok® adapters (delivered in a separate bag).
    1. Insert the nut of the adapter over the oil pipe or hose.
    2. Insert the two ferrules over the pipe or hose. Make sure they are in the order and orientation shown in Figure 1.
    3. Push the pipe or hose into the fitting on the DGA monitor and rotate the nut finger-tight.
    4. Mark the nut position.
    5. Hold the base of the oil fitting with a second wrench to keep it from turning when tightening.
    6. Tighten the nut 1 1/4 turns with a wrench.
    If you are not using the recommended oil pipe size, install adapters into the oil connections first. Then connect the oil pipe to the adapter.
    Figure 1. Pipe or hose connection fitting order
    Oil fitting on the DGA monitor
    Front ferrule
    Back ferrule
    Nut of the adapter
    Oil pipe
  11. Install trace heating for the pipes if you are using the device with synthetic ester liquid or if it is necessary due to a cold climate for a device with mineral oil. The heating cable must touch the pipes for optimal heat transfer.
  12. Install insulation over the whole length of the inlet and outlet pipes and the pipe connectors if you are using the device with synthetic ester liquid or if it is necessary due to a cold climate for a device with mineral oil.
    Protect the insulation from potential damages caused by animals.
  13. Install pipe supports where necessary to support the pipe mechanically. The pipe should be supported at least every 2 meters (6 feet).
  14. Add the transformer valve tags to the transformer intake and return valves.
To verify that the oil connections are tight, check for leaks during commissioning when the DGA monitor is pumping oil. Ideally, check the connections again after the DGA monitor has been running for some time (for example, the next day).