Low-Frequency EI Transformers for OEM Equipment Manufacturers

They identify the nominal EI lamination family and are normally related to the centre-leg or outside dimensions, depending on the manufacturer's convention. The code alone does not define VA, stack thickness, bobbin, mounting or electrical performance, so a complete drawing is still required.

Core size is selected from VA, frequency, acceptable flux density, copper window area, regulation, temperature rise, ambient, duty cycle and size limits. Two transformers with the same output VA may need different cores if one has tighter regulation or operates in a hotter enclosure.

Define the input condition, load current, load type, frequency and whether tolerance applies at no load or rated load. A realistic tolerance prevents unnecessary oversizing. If the downstream circuit includes a rectifier and regulator, specify the minimum DC voltage needed at worst-case mains and load.

Provide the required DC voltage and current, bridge-rectifier type, capacitor value, ripple limit and downstream regulator information. Capacitor charging creates narrow current pulses, so transformer secondary RMS current and heating cannot be estimated from DC output current alone.

Yes, if the windings are designed for it. Series connection requires correct phase identification. Parallel connection also requires closely matched voltage and impedance; otherwise circulating current can occur. The approved wiring diagram should show every permitted connection.

Two equal primary windings are connected in parallel for the lower mains voltage and in series for the higher mains voltage. Phasing is critical. ECKO supplies numbered or colour-coded leads and a connection diagram, but the final equipment should prevent incorrect user wiring.

Use an isolation transformer when galvanic separation is required between input and output. An autotransformer can be smaller and more economical for some voltage-conversion tasks, but input and output are electrically connected. The choice must follow the end-product safety and circuit requirements.

They describe thermal classes of insulation systems and their material temperature capability. They do not mean the transformer should normally operate at that maximum temperature. Ambient, winding temperature rise, hot spot allowance and equipment life expectations must still be defined.

No. Surface temperature depends on where and how it is measured, while winding temperature rise is normally evaluated by an approved method such as resistance change. The test method, ambient, warm-up duration, load and installation condition must be consistent when comparing results.

Higher input voltage increases core flux, no-load current and core loss and may raise temperature or acoustic noise. Send the true minimum and maximum mains voltage rather than only the nominal value so the design can maintain adequate margin.

A one-shot thermal fuse or resettable protector can be positioned within the insulation system where appropriate. Its rating and location must coordinate with normal temperature, abnormal operation, accessibility and the end-product protection strategy.

Varnish impregnation helps bind windings and laminations, improving mechanical stability and often reducing hum. Full encapsulation provides more environmental and mechanical protection but changes heat dissipation, dimensions, weight and approval considerations. It must be included in the thermal design.

Specify the input voltage and waveform, load, mounting, background noise, measurement distance and pass criterion. A transformer measured on a soft bench may sound different when bolted to a resonant metal panel, so equipment-level evaluation is important.

Electrical output normally remains the same, but orientation can change natural convection, hot-spot temperature, mechanical stress and chassis vibration. Inform ECKO if the transformer will be mounted vertically, inverted or close to another heat source.

Often, but reducing height may require a larger lamination footprint, a different core stack or revised mounting. ECKO can compare alternative geometries against regulation, temperature rise, leakage field and tooling constraints.

They depend on working voltage, insulation category, pollution degree, material group, altitude, applicable standard and whether basic, supplementary or reinforced insulation is required. These inputs should be confirmed before bobbin and winding construction are fixed.

Depending on the project, ECKO can provide an outline drawing, wiring diagram, electrical specification, label drawing, test report and relevant material or compliance documents. Required records should be listed during quotation so their scope is agreed.

The accepted sample is linked to released drawings, winding data, bill of materials and test limits. First-off checks and routine tests verify production. Any requested material or process change should pass documented review before implementation.

Customer part numbers, lead labels, connection diagrams, carton labels, individual protection and pallet requirements can be incorporated after artwork and packing approval. Barcodes and traceability information can also be discussed.

Timing depends on design complexity, materials, tooling, test requirements and sample quantity. Straightforward qualified designs may be completed quickly, while new bobbins, agency materials or special validation require more time. ECKO confirms the schedule after technical review.