Mechanical Installation - MHT410

MHT410 Quick Guide

Document code
English (United States)
Document type
User guide
CAUTION Before you install the transmitter:
  • Make sure there is no negative pressure in the transformer. If there is negative pressure when you open the bleed screw during installation, air will flow into the transformer oil tank.
  • Do not open the ball valve on the transformer until you are instructed to do so in this guide.
  • Make sure the bleed screw on the mounting nut is closed.
  • 2 wrenches (50 mm and 36 mm)
  • Allen key (3 mm, provided)
  • PTFE tape (provided)
  • Gloves
  • Bucket and cloth
  1. Remove the protective cap with sorbent packet from the mounting nut.

    In case of rain, do not let any water fall on the filter.

  2. Apply PTFE tape tightly on the mounting nut threads.
    1. Before you start, clean the threads with a cloth.
    2. To make sure you wrap the tape in the correct direction, hold the transmitter so that the product label is facing you and the mounting nut points away from you.
    3. Start wrapping counter-clockwise from the second thread on the tip of the mounting nut.
    4. Wrap each round very tightly about half way on top of the previous round so that the tape overlaps. Stretch the tape for optimal tightness. Apply a couple of rounds of tape.
  3. Make sure the bleed screw is closed. Fasten the mounting nut on the ball valve to finger-tightness with your hand. Leave the bleed screw directly on top of the nut.

    If you cannot position the bleed screw on top of the mounting nut by tightening just with your hand, you can use a wrench (50 mm) to turn the mounting nut a maximum of a ½ turn.

    CAUTION If you need to loosen the mounting nut after you have fastened it on the valve, you must remove the transmitter from the valve, remove the PTFE tape, and start again from 2 with new PTFE tape.
  4. With a 3 mm Allen key, loosen the bleed screw. Place a bucket under the mounting nut.
  5. Start opening the valve very carefully to let air out through the bleed screw.
    CAUTION If you open the valve too quickly, the air inside the mounting nut will flow into the transformer instead.

    When oil flows out, close the bleed screw. Clean the area with a cloth and open the ball valve fully.

  6. Continue tightening the mounting nut with a wrench. Be very careful not to over-tighten the connection. Approximately 5 ... 8 mm of the mounting nut threads remain outside the valve.

    If the connection leaks after you have tightened the mounting nut, check the thread type of the installation valve.

    • If the valve thread is other than female 1.5" NPT (incorrect), do not install the transmitter in that valve.
    • If the valve thread is female 1.5" NPT (correct), close the valve, open the mounting nut and remove the transmitter, remove old PTFE tape and apply a thicker layer of new PTFE tape. Then continue from 3.
  7. Push the probe to the correct depth. The correct depth depends on where the installation valve is located: radiator pipe or transformer wall.
    • Valve in radiator pipe: Install the probe so that the back of the weather shield is 180 ... 190 mm from the pipe surface.
    • Valve in transformer wall: Install the probe so that the back of the weather shield is 200 mm from the transformer wall.
      DANGER Severe risk of death and of damage to transformer:

      Pay attention to transmitter installation depth and possible energized parts inside the power transformer to minimize electric shock hazard and equipment damage.

    When the probe is in the correct depth, turn the transmitter 90 degrees two to three times to remove any air bubbles from the sensor area.

  8. Tighten the small tightening nut with a wrench until the probe is securely fastened.
  9. Press the caution sticker on the MHT410 weather shield or other visible location nearby, and lock the handle of the valve in the open position with the safety pin.