ET3S2 / ET3V1 / EA3 / EA3R — Scott-Connected and Open-Delta Transformers, Autotransformers and Starting Autotransformers (LV)
Country: Poland · Model: ET3S2 / ET3V1 / EA3 / EA3R
Special low-voltage transformers up to 1 000 V with non-standard connections, among them ET3S2 with the Scott connection, ET3V1 with the Vv connection, EA3 autotransformers and EA3R starting autotransformers. Frequency is 50/60 Hz, protection class I. They are used where an ordinary three-phase transformer does not fit in terms of circuit or starting mode.
- ET3S2
- Scott connection 3→2 phase (90°), EN/IEC 61558-1
- ET3V1
- Vv (open delta) connection 3→1 phase, EN/IEC 61558 or 60726
- EA3
- three-phase autotransformer, EN/IEC 61558-2-1, IP00 or IP23
- EA3R
- starting autotransformer, EN/IEC 60726, IP23, multi-tap
Technical specifications
| ET3S2 | Scott connection 3→2 phase (90°), EN/IEC 61558-1 |
|---|---|
| ET3V1 | Vv (open delta) connection 3→1 phase, EN/IEC 61558 or 60726 |
| EA3 | three-phase autotransformer, EN/IEC 61558-2-1, IP00 or IP23 |
| EA3R | starting autotransformer, EN/IEC 60726, IP23, multi-tap |
| Voltage | up to 1 000 V |
| Insulation class | B up to 5 kVA / F above 5 kVA (EA3, ET3V1); F (ET3S2, EA3R) |
| Climate | C1/E0 land; C2/E1 marine/mining |
| Frequency | 50/60 Hz |
Replacement for
no direct analogue; Scott/Vv connection types are not series-produced; closest — OSM1, TSZI, starting autotransformers (general type)
selected by purpose and main parameters, please confirm with the manager
Specifications are taken from the manufacturer’s technical documentation. Updated .
Description
ET3S2 converts a three-phase supply into two-phase with a 90° shift and consists of a main and an auxiliary transformer. With a symmetrical two-phase load the supply network is also loaded symmetrically, so imbalance currents are smaller. ET3V1 with the Vv connection supplies a high-power single-phase consumer with two transformers instead of three, and the load falls more evenly on the phases. The EA3 autotransformer has electrically connected windings, so it is lighter and more compact than an ordinary transformer of the same throughput power. The price is the lack of galvanic isolation, lower resistance to short-circuit currents, and the impossibility of changing the earthing type, for example from IT to TN-C. EA3R reduces the voltage at the motor during starting and limits the starting current where star-delta switching is not enough. For thruster devices there is the marine version EA3RM-Compact. Mounting is on angle brackets.
How to choose
First determine the task, a two-phase load (ET3S2), a high-power single-phase consumer (ET3V1), voltage reduction without isolation (EA3) or motor starting (EA3R). If isolation is mandatory, an autotransformer is not suitable. The insulation class of EA3 and ET3V1 depends on power, B up to 5 kVA and F above. The C1/E0 version is intended for land installations, C2/E1 for marine and mining ones, with a design temperature of 40/45 °C. For supplying railway signalling devices there is ET3KOL, and for marine transformers of 400–1 600 kVA ET3SM.
Request a price and lead time
ET3S2 / ET3V1 / EA3 / EA3R — Scott-Connected and Open-Delta Transformers, Autotransformers and Starting Autotransformers (LV). We reply within one business day.
Or email office@usk.ua or call +38 (044) 339-50-20.
FAQ
What is the Scott-connected transformer ET3S2?
It converts a three-phase supply into two-phase with a 90° phase shift. It consists of two transformers, a main and an auxiliary one, is made to EN/IEC 61558-1, and has insulation class F.
How does the EA3 autotransformer differ from an isolating transformer?
The windings are electrically connected and there is no galvanic isolation, so interference passes between the sides. Made to EN/IEC 61558-2-1, degree of protection IP00 or IP23.
What is the starting autotransformer EA3R needed for?
It reduces the motor voltage during starting and limits the starting current, in particular when star-delta switching is not enough. Made to EN/IEC 60726, IP23, class F, and a multi-tap variant is possible.
Why use the Vv connection for a single-phase load?
Two transformers instead of three, connected at the required angle, distribute the load more evenly across the phases and take up less space. ET3V1 is made to EN/IEC 61558 or 60726.
What voltage and frequency are these transformers designed for?
Up to 1 000 V and 50/60 Hz, protection class I.
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Need a price, lead time or replacement?
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