Frequently Asked Questions

We are a low voltage transformer manufacturer based in Yueqing, Zhejiang, China — the home of China’s low voltage electrical industry. Wilmall supplies step up / step down transformers, control transformers and variable transformers to distributors, wholesalers, OEM brands and project buyers in over 30 countries, mainly in the Middle East, Southeast Asia, Africa and South America.

Our transformers are manufactured under a quality system aligned with ISO 9001, and the main series carry CE and RoHS compliance. For specific certification needs in your market (e.g. SASO for Saudi Arabia, SONCAP for Nigeria), contact us — we can provide the required documents for your customs clearance. The full list is on our certifications page.

Our factory focuses on low voltage transformer production, with dedicated lines for winding, assembly and final testing of step up / step down and variable transformers. Capacity ranges from small batch samples to container orders. Stock DT units start at 1 pc and custom-voltage units at 10 pcs per spec, so even a first-time buyer can open with a trial order.

Yes. OEM / ODM is our core business. You can customize:

• Voltage & capacity (100W – 10KVA input/output combinations)
• Enclosure (metal / plastic, color, size)
• Label & packaging (your brand name, logo, carton design)
• Cable / socket / fuse options (e.g. RCD protection, US/EU/UK plug)

Minimum order for label changes: 10 pcs. A custom printed colour box needs 1,000 pcs for the first print run.

We supply to distributors and OEM brands across the Middle East, Africa and Southeast Asia. Examples include step down transformers for household appliance distributors, control transformers for machine builders, and variable transformers for laboratory equipment suppliers. If you want references in your market, send us an inquiry and we will share relevant case details under NDA.

Our product range covers:

• Step Up & Step Down: 100W – 10KVA, common conversions such as 110V↔220V, 110V↔230V, 220V↔380V
• Control Transformer: 40VA – 1.5KVA (JBK3 series, VDE0550 / IEC standard)
• Variable Transformer (Variac): 0.5KVA – 5KVA, 0-130V / 0-260V output

Both 50Hz and 60Hz are supported. Non-standard voltage custom winding is available from 100W.

The main series are designed to meet IEC / VDE related requirements for low voltage transformers, with JBK3 control transformers referencing VDE 0550 / IEC. For your market’s mandatory certifications (SASO, SONCAP, BIS etc.), we can prepare the needed documentation and samples.

• DT – dual-purpose step up & step down transformer, commonly used for 110V↔220V appliance conversion
• ST – step down transformer, e.g. 220V to 110V; some models include RCD / residual current protection
• STU – universal step up & step down with wider capacity range

All three share the same core quality standard; the difference is direction flexibility and added safety options.

For low voltage (≤1KV) applications we supply dry-type transformers — lighter, safer for indoor use, no oil maintenance. Oil-immersed units are generally for medium/high voltage distribution and are not our focus.

MOQ depends on how much of the unit is customised:

• Stock DT units (110V ↔ 220V): 1 pc. They are packed in our own warehouse and ship in 3–5 working days. Wattages can be mixed in one shipment, so 1 × 1000VA plus 1 × 2000VA is a valid trial order.
• Custom voltage (100V, 120V, 230V, 240V, 380V …): 10 pcs per spec, wound to order, 15–25 days.
• Custom socket / plug type (US, UK, EU, AU, JP, KR, ZA, BR …): 50 pcs.
• Custom printed colour box: 1,000 pcs for the first print run, because the print plate is made once. Below that we ship neutral white boxes with your label sticker, and the label design is free with no extra MOQ.

Sample: yes — sample orders are welcome before bulk production. Sample lead time is usually 5–7 days, and the sample cost is deducted from the first bulk order.

We accept T/T (bank transfer) as standard, with 30% deposit + 70% balance before shipment. For larger or repeat orders we can discuss L/C at sight or trade assurance through platforms.

Lead time depends on whether the unit is stock or wound to order:

• Stock units (standard 110V/220V, no customization): dispatch in 3–5 working days
• Samples: 5–7 days
• Standard production order (≤ few hundred pcs, custom voltage): 15–20 days
• Container order or custom enclosure: 20–25 days

Wound-to-order production is 15–25 days after deposit depending on quantity and customization.

We confirm the exact schedule in the PI (Proforma Invoice) so you always know the ship date.

We ship from Ningbo / Shanghai ports (both near our factory in Zhejiang), by sea, air or express:

• Sea (FOB/CIF/CFR): most economical for bulk orders to Middle East, Africa, SE Asia
• Air / Express (DHL, FedEx, UPS): for samples and urgent small orders

Stock units are dispatched within 3–5 working days of payment clearing; wound-to-order units follow the 15–25 day production schedule above.

We provide a 12-month warranty against manufacturing defects. If a unit fails within warranty, we repair or replace it — for small quantities we typically ship replacement units directly. Our engineers can support you via WhatsApp / email with wiring and troubleshooting guidance.

1. Check your appliance’s input voltage (e.g. 110V) and rated power (watts)
2. Pick a transformer with capacity ≥ appliance watts × 1.3 (safety margin; motors, ACs and compressors need 2–3× for start-up surge)
3. Match the output voltage to your appliance

Example: a 1500W appliance → choose at least 2000VA step down transformer.

Our dry-type transformers are rated for normal operating environments (-10°C ~ +45°C, humidity ≤ 85% RH). For hot or humid regions (Gulf countries, tropical Africa), we recommend sizing with extra capacity margin, adequate ventilation, and asking about moisture-resistant treatment for special projects.