An isolation transformer, also referred to as an insulating transformer, is one where the primary and secondary windings are separate, as opposed to an autotransformer where the primary and secondary share a common winding.

Transformers may be used at ambients less than 40°C at full nameplate capacity. For ambients above 40°C, they must be derated. Contact Micron for further information.

A transformer may be used at full nameplate capacity up to 3300 feet (1000 meters). Above that altitude, the capacity of the transformer should be derated by 0.3% for each 300 feet of elevation above 3300 feet.

Regulation is the change in output voltage when the load is reduced from rated value (full load) to zero (no load) with input voltage remaining constant.

Taps are provided to compensate for voltage variation either higher or lower than normal while allowing the transformer to deliver rated output voltage at full VA. The standard designations for taps are Full Capacity Above Normal (FCAB) and Full Capacity Below Normal (FCBN).

Temperature rise is the difference between the average temperature of the transformer windings and the ambient temperature.

The hot spot is an allowance selected to approximate the difference between the highest temperature inside the transformer coil and the average temperature of the transformer coil.

One insulation system is not necessarily better than another. Each will typically provide a comparable life expectancy. The choice of an insulation system depends upon application, performance, and cost considerations.

Single phase transformers may be used in a three phase application in one of the following ways:

• Connect the primary leads to any two wires of the three phase source to obtain a single phase output using a single transformer.
• Bank three single phase transformers to be connected in either a delta-delta or delta-wye configuration for a three phase output. The equivalent three phase capacity when properly connected is three times the nameplate rating of each individual single phase transformer.

Transformers are typically wound with either copper or aluminum conductors. There is no difference in ultimate electrical performance between the two. All Micron General Purpose and Buck-Boost transformers 2KVA and below are copper wound. Units 3KVA and larger are aluminum.

In general there are three basic enclosure types.

• Type 1 – Intended for indoor use primarily to provide protection from incidental contact with current carrying parts.
• Type 2 – Intended for indoor use primarily to provide protection for the component from limited amounts of moisture and dust.
• Type 3R – Intended for indoor/outdoor use primarily to provide protection form rain, ice, and moisture.

All Micron General Purpose Type 1-E and 3-E and Buck-Boost transformers are in a 3-R enclosure.

Single phase General Purpose transformers rated 3KVA and above can be reverse connected with no loss in capacity and with voltage stability. Single phase units rated 2KVA and below have compensated windings. These may be reverse connected, but the output voltage will be less than nameplate due to the compensation factor of the windings.

Units designed for 50/60Hz operation can be utilized at frequencies up to 400 Hz. Units designed for 60 Hz can similarly be used at frequencies up to 400 Hz but cannot be used at 50 Hz operation.