Dry-Type Transformers suitable for indoor and outdoor applications anywhere that safe and dependable power are important. Cooling ducts in the windings allow heat to be dissipated into the air. Dry-types can operate indoors under almost all ambient conditions for commercial buildings and light manufacturing facilities.
Under normal conditions, standard rating dry-type distribution transformers can be installed at an altitude of less than 1000 m (3300 ft), with an ambient temperature that does not exceed 30 °C as a daily average or 40 °C at any time, and which does not fall below –20 °C.
Non-ventilated dry-type transformers should be provided with a weather-resistant enclosure when used in outdoor applications. Facility management teams should also consider ambient temperature and altitude.
Dry-type transformers are available in three general classes of insulation. The main features of insulation are to provide dielectric strength and to be be able to withstand certain thermal limits. Insulation classes are:
Temperature rise ratings are based on full-load rise over ambient (usually 40°C above ambient and are 150°C (available only with Class H insulation), 115°C (available with Class H and Class F insulation) and 80°C (available with Class H, F, and B insulation). A 30°C winding hot spot allowance is provided for each class. The lower temperature rise transformers are more efficient, particularly at loadings of 50% and higher. Full load losses for 115 °C transformers are about 30% less that those of 150°C transformers. And 80°C transformers have losses that are about 15% less than 115°C transformers and 40% less than 150°C transformers. Full load losses for 150°C transformers range from about 4% to 5% to 30 kVA and smaller to 2% for 500 kVA and larger. When operated continuously at 65% or more of full load, the 115°C transformer will pay for itself over the 150°C transformer in 2 yrs or less( 1 yr. if operated at 90% of full load). the 80°C transformer requires operation at 75% or more of full load for a 2-yr payback, and at 100% load to payback in 1 yr over the 150°C transformer. If operated continuously at 80% or more of full load, the 80°C transformer will have a payback over the 115°C transformer in 2 yrs or less. You should note that at loadings below 50% of full load, there is essentially no payback for either the 115°C or the 80°C transformer over the 150°C transformer, Also at loadings below 40% the lower temperature rise transformers become less efficient that the 150°C transformers. Thus, not only is there no payback, but also the annual operating cost is higher.
1. Ambient air temperature: -5~+40 and the average temperature should not exceed +35 in 24h.
2. Install and use indoors. Altitude above sea level for operation site should not exceed 2000M.
3. Relative humidity should not exceed 50% at max temperature +40. Higher relative humidity is allowed at lower temperature. Ex. 90% at +20. But in view of the temperature change, it is possible that moderate dews will produce casually.
4. Installation gradient not exceed 5.
5. Install in the places without fierce vibration and shock and the sites insufficient to erode the electrical components.
6. Any specific requirement, consult with manufactory.