T&D World Magazine

Differential Temperature Monitor Provides Early Warning Indication

Qualitrol's 110 series differential temperature monitor provides an early warning indication of pending load tap changer problems due to coked or worn contacts. Coked and worn contacts are the dominant failure modes in LTCs.

Typically, if the LTC gets hotter than the main tank by even a modest amount, a problem exists. To monitor and determine if the LTC tank temperature is healthy, the ambient and loading conditions must be accounted for. With the Qualitrol 110 DTM, the LTC tank temperature is compared to the main tank temperature to accomplish this.

The 110 DTM monitors the temperatures of the main transformer tank and the LTC tank and calculates the difference between the two.

There are three indicating displays: main tank, LTC tank, and differential. A single alarm output contact can be set by the user to operate off of any given differential, positive or negative. An adjustment inside the device allows an adjustment of delay time between the main and LTC tanks, since one may lag behind the other.

  • Well-mount RTD or magnetic tank mount sensors
Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.