Micron Industries Low Voltage General Purpose Transformers General Product Line Information

Low Voltage General Purpose Transformers

UL Listed, CSA Certified

Single Phase
Type 1-E
Encapsulated

UL Listed
Three Phase
Type 3-E
Encapsulated

UL listed
Single Phase
Type 1-V
Ventilated

UL Listed
Three Phase
Type 3-V
Ventilated

Type 1-E general purpose
transformers are single
phase, resin encapsulated
designs suitable for indoor
or outdoor applications. It's
totally enclosed, non­ventilated enclosure make
it ideally suited for use in
areas that contain dust,
moisture, or corrosive
fumes. Available in ratings
through 25 KVA type 1-E
transformers can be
mounted in any position for
indoor installations and in
upright positions only for
outdoor installations.

Type 3-E resin
encapsulated, 3-phase
transformers are available
in ratings of 3-75 KVA. Its
totally enclosed non­ventilated enclosure makes
the 3-E ideally suited for
outdoor as well as indoor
locations. Type 3-E
transformers utilize the
185°C insulation system
with 115°C rise. 3-E
transformers 3-15 KVA are
T-T connected.

1-V general purpose
transformers are single
phase ventilated units
designed primarily for
indoor locations (also for
outdoor , 600 volt class
with the addition of
weathershields). The 1-V
utilizes a 220°C insulation
system with 150°C rise and
is available in ratings of 15­167 KVA.
1-V products are compliant
to DOE 2016.

The 3-phase 3-V ventilated
dry-type is available in
ratings of 15-750 KVA. Its
220°C insulation system
(150°C rise) is self­extinguishing. 3-V
enclosures are designed for
indoor locations (or
outdoor, 600 volt class with
addition of
weathershields).
3-V products are compliant
to DOE 2016.

Mounting

Units installed outdoors must be mounted in upright position.

Efficiency

The Micron series of ventilated, three-phase, 600 volt class general purpose distribution transformers meet the DOE
2016 efficiency requirements and federal energy efficiency laws. New distribution transformers installed in the United
States are required to meet these energy efficiency requirements as of January 2016.

Winding Terminations
Primary and secondary windings are terminated in the wiring compartment. Encapsulated units have copper leads or
stabs brought out for connections. Micron recommends external cables be rated 90°C (sized at 75°C ampacity) for
encapsulated designs.

Series-Multiple Windings
Series-multiple windings consist of 2 similar coils in each winding which can be connected in series or parallel
(multiple). Transformers with series-multiple windings are designated with an "X" or"/" between the voltage ratings.
such as primary voltage of "120/240" or "240 X 480". If the series-multiple winding is designated by an "X" the winding
can be connected only for a series or parallel. With the"/" designation, a mid-point also becomes available in addition
to the series or parallel connection. As an example, a 120 X 240 winding can be connected for either 120 (parallel) or
240 (series), but a 120/240 winding can be connected for 120 (parallel), or 240 (series), or 240 with a 120 mid-point.

2

Ambient

+

Winding

Rise

+

Hot

Spot

=

Temp.

Class

The design life of transformers having different insulation systems is the same – the
lower temperature systems are designed for the same life as the higher temperature
systems.

40°C

55°C

10°C

105°C

40°C

80°C

30°C

150°C

40°C

115°C

30°C

185°C

KVA

NEMA Average₁
Sound Level in dB

All Micron 600 volt class dry-type distribution transformers are designed to meet
NEMA ST-20 levels as listed.

0-9

40

10-50

45

51-150

50

151-300

55

301-500

60

General Information

Industry Standards
All Micron dry-type distribution and control transformers are built and tested in accordance with applicable NEMA,
ANSI and IEEE standards. All 600 volt class transformers are UL listed unless otherwise noted.

Seismic Qualified
The Micron family of dry-type distribution transformers is seismically tested, seismically qualified, and exceeds
requirements of the Uniform Building Code (UBC) and California Code Title 24.

Frequency
Micron standard dry-type distribution transformers are designed for 60 Hz operation. Transformers required for other
frequencies must be specifically designed.

Overload Capability
Short term overload is designed into transformers as required by ANSI. Basically, dry-type distribution transformers
will deliver 200% nameplate load for one-half hour; 150% load for one-hour; and 125% load for four-hours without
being damaged provided that a constant 50% load precedes and follows the overload. See ANSI C57 .96-01.250 for
additional limitations.
Continuous overload capacity is not deliberately designed into a transformer because the design objective is to be
within the allowed winding temperature rise with nameplate loading.

Insulation System & Temperature Rise
Industry standards classify insulation systems and rise as shown below:

Insulation System Classification

Sound Levels

₁. Applies to general purpose transformers only.

3