Strip Heater in "Cooking" Room Solves Shocking Problem of High Voltage Transformers

Chromalox catalog strip heaters

The Challenge
The numerous high voltage transformers located outdoors and on poles are constantly subjected to the heavily moisture-laden atmosphere. Between the moisture and the operating voltages (which run from 120 volts up to 7,620 volts), the transformers develop a variety of faults. These faults can prove devastating to the equipment and fatal to linemen. A flashover between terminals due to water logging may split a ceramic insulator and make the metal transformer case "hot" and lethal. A gasket may deteriorate permitting the water to enter the transformer casing or lightning can break the casing. The insulating oil in the transformer may be of lower quality due to moisture seepage or breakdown from flashover and damage the coils.

The Solution
Remove the transformers that "look or test suspiciously" to the shop drying room for a thorough "cooking". The drying room is constructed of concrete and equipped with banks of Chromalox strip heaters mounted behind screens. At temperatures maintained between 140-155°F., the transformers are dried out until they test safe for operation. During the year of operation the heaters have been operating continuously on a round the-clock basis every day and have never been shut down. The installation consists of 9,000 watts of Chromalox strip heaters operating on 230 volts. The temperature is controlled by a thermostat mounted outside the "cooking" room. More than 125 transformers are returned, ready for service every month. The thorough "cooking" they get from the Chromalox Strip Heaters insures safety to personnel and equipment and helps to stabilize the distribution system.


  • Reliable strip heaters operate round-the-clock without maintenance.
  • Easily produce the exact temperature needed.
  • No excess fumes or heat requiring ventilating system.
  • It is a clean heat source.
  • No attendance is required.
  • Installation is simple.