Working principle of Czech Ismet single-phase stepper transformer SST 1.5

Working principle of Czech Ismet single-phase stepper transformer SST 1.5

ST 1.5 belongs to the "single-phase step up transformer" series produced by Ismet at its factory in Brno, Czech Republic, with a rated capacity of 1.5 kVA. It is used to increase the input voltage from 110-230 V to 240-600 V in 16 step mode in a 50/60 Hz power grid, providing safe and adjustable isolated power for high-voltage test benches, X-ray equipment, or long-distance local lines.

Electromagnetic core principle

Like other Ismet single-phase transformers, SST 1.5 follows the classical law of electromagnetic induction:

Vp / Vs = Np / Ns

Among them, Np and Ns are the number of turns of the input and output windings, respectively.

The special feature is that the secondary winding is divided into 16 segments, with a fixed number of turns Δ N for each segment. By rotating the step selector on the front panel, each segment can be "series added" or "bypassed", thereby changing Ns in a 16 level linear stepping manner and achieving 16 level output voltage.

Mechanical electrical structure

Core: High quality oriented silicon steel sheet, 45 ° oblique seam, reducing no-load loss;

• Winding: 100% copper wire, vacuum impregnated with H-grade insulation paint, heat-resistant to 180 ° C;

Step switch: Ismet five contact ball bearing mechanism, silver alloy contacts, rated 10A, mechanical life 30000 times;

• Shell: Steel plate bending+powder coating, IP21， The top detachable junction box is convenient for on-site wiring changes.

workflow

① 220V single-phase mains power connected to primary terminal L/N;

② When the stepper switch is in position 0, the secondary is open and outputs 0 V;

③ Rotate clockwise, every 22.5 °, the number of secondary series turns Ns increases by Δ N, and the output voltage increases in steps of about 25 V/step;

④ When reaching the 16th gear, Ns reaches its maximum and the output reaches the rated maximum of 600 V;

⑤ The entire switching process is carried out under zero or light load to avoid arcing during on load switching.

Energy and Protection

Efficiency η ≥ 95% (@ 75% load), no-load loss<12 W;

Built in 130 ° C resettable thermal protector, automatically disconnects the primary when overloaded;

Double insulation barriers shall be installed between all windings and the iron core to meet the safety isolation requirements of EN 61558-2-13.

Technical Specifications:

ST 1.5

Power: 285.00 VA

U.p.220 in u.sec: 80... 190 in.

Single-phase stepper transformer

I. SEC: 1.5 A

Core type: EI84a/29.5 Winding: Partition

Protection level: IP 00 Protection level: I Preparation

Test voltage: 2.5 kV, compliant with VDE 0570 T2-13

And agreements between customers and suppliers

Environmental temperature: TA 40/E Frequency: 50 Hz

PRI connection: terminals

SEC Connection: Terminal

U.SEK: 80-110-130-150-170-190 V

Base bracket with ismet and DIN mounting dimensions

CU 0.40 kg

FEN 1.10 kg

Working principle of Czech Ismet single-phase stepper transformer SST 1.5