TRANSFORMERComplete units
Dry-Type Transformers
Cast-resin dry-type transformers supplied through qualified manufacturing partners to the agreed ratings and enclosure requirements for indoor installations.
01 / Specification
Transformer specification
- Insulation system
- Epoxy cast-resin HV windings
- Thermal class
- Class F or H, as specified
- Cooling
- AN; AF with cross-flow fans
- Conductors
- Copper or aluminium
- Enclosure
- Open core-and-coil or enclosure to the specified IP rating
- Monitoring
- Winding temperature sensors with controller for fans, alarm and trip
Rated power, HV / LV voltages, impedance, losses, frequency (50 / 60 Hz) and vector group are defined per project. Design basis: IEC 60076-11 or the specified project standard.
02 / Construction
Built for indoor installation
Construction
Cast-resin HV coils
HV windings are encapsulated in epoxy resin: no oil, a low fire load and resistance to humidity and dust.
HV connections and tapping links to the approved drawing.
Construction
LV busbar terminals
LV connections are brought out on busbars, arranged for cable or busduct termination.
Terminal position and busbar drilling confirmed per project.
Construction
Magnetic core
CRGO laminations stacked to the lamination schedule and clamped in a steel frame; core surfaces are sealed against corrosion.
Core steel grade and loss basis stated in the offer.
03 / Cooling and enclosure
Rated for the room it stands in
AN / AFAir cooling
Natural air cooling at rated power. Cross-flow fans below the coils add forced-air cooling for peak load; fan duty follows the temperature controller.
IPEnclosure
Supplied open for a switch room, or in a steel enclosure with the specified IP rating, cable entry and ventilation.
04 / Testing
Routine tests before dispatch
- 01Winding resistanceMeasured on each winding and corrected to reference temperature.
- 02Voltage ratio and phase displacementRatio checked on the tap positions; vector group verified.
- 03Impedance and load lossShort-circuit impedance and load loss at rated current.
- 04No-load loss and currentMeasured at rated voltage and frequency.
- 05Dielectric testsSeparate-source AC and induced-voltage withstand.
- 06Partial dischargePartial-discharge measurement on the complete transformer.
Routine tests to IEC 60076-11 unless the project standard differs. Type tests, special tests and witnessed testing are agreed at order.
05 / Project definition
Define the transformer before the offer
Typical applications
- Commercial buildings and data centres
- Hospitals and public buildings
- Industrial plants and switch rooms
- Tunnels, rail and underground sites
Specification checklist
Rated power, HV / LV voltages, frequency, vector group, impedance, thermal class, cooling, enclosure and IP rating, installation site and destination.
Before ordering
When is a dry-type transformer the better choice?
Where fire risk, oil containment or environmental rules exclude oil: inside buildings, close to people and in underground or enclosed spaces.
What does maintenance involve?
No oil sampling. Keep the coils clean and dry, check the connections and verify the temperature controller at the intervals given in the manual.
Which enclosure should be specified?
State the IP rating, cable entry (top or bottom) and ventilation. The enclosure is confirmed with the general arrangement drawing.
Which documents come with the transformer?
The general arrangement drawing, nameplate data and routine test report are typical. Further documents are agreed per order.
RFQTechnical review
Send your transformer specification
Include rated power, HV / LV voltages, vector group, enclosure and destination.