factory price dc winding resistance tester suppliers - Bulk Supply and Specification Guide
Scope of Supply and Physical Form
Replacement rate, not unit price, drives the real cost of ownership for transformer and motor manufacturers running three-shift test lines. A tester that drifts out of calibration after six months forces recertification downtime, scrapped winding batches, and warranty claims that dwarf any per-unit saving.
Standard supply includes the measurement mainframe, a matched set of Kelvin leads (2 m or 5 m), temperature probe, USB stick with PC software, and a factory calibration certificate traceable to national standards. Rack-mount ears and a 19-inch drawer slide kit are optional for bench integration; a padded transit case with custom foam inserts is standard for portable models.
Desktop / Bench Series
- 10 A / 20 A / 50 A test current variants
- 7-inch capacitive touchscreen, 800×480
- Internal 8 GB storage, USB host & device
- Mains 110/220 V auto-range, 50/60 Hz
High-Current Floor Series
- 100 A / 200 A continuous, 300 A pulse
- Forced-air cooling, thermal foldback at 55 °C
- Three-phase simultaneous measurement
- IEC 61010 CAT III 600 V rated enclosure
How It Performs in Use
Tooling amortisation decides whether a 0.05 % accuracy class pays for itself. On a 500 kVA transformer line, a 0.2 % class tester adds ±4 mΩ uncertainty on a 2 Ω LV winding — enough to misclassify a marginal joint as acceptable. The 0.05 % class reduces that band to ±1 mΩ, cutting false-pass risk by a factor of four.
Four-wire Kelvin measurement eliminates lead resistance, but only if the injector and sense clips mate cleanly. Oxidised clips add 20–50 µΩ per contact; the firmware compensates up to 500 µΩ total, beyond which it flags "check connections" and aborts. Demagnetisation after each test clears residual flux in core-type windings, preventing the next measurement from reading 3–5 % high.
| Parameter | Desktop 20 A | Floor 100 A | Floor 200 A |
|---|---|---|---|
| Range (auto-ranging) | 0.1 µΩ – 20 kΩ | 0.1 µΩ – 5 kΩ | 0.1 µΩ – 2 kΩ |
| Best accuracy | ±(0.05 % rdg + 0.5 µΩ) | ±(0.05 % rdg + 1 µΩ) | ±(0.1 % rdg + 2 µΩ) |
| Resolution | 0.1 µΩ | 0.1 µΩ | 0.1 µΩ |
| Test time (typical) | 3–8 s | 5–12 s | 8–18 s |
| Temp. compensation | Cu / Al, -20 to 80 °C | Cu / Al, -20 to 80 °C | Cu / Al, -20 to 80 °C |
| Data export | CSV, PDF, MODBUS TCP | CSV, PDF, MODBUS TCP, OPC UA | CSV, PDF, MODBUS TCP, OPC UA |
Materials and Construction Trade-offs
Cheaper stock options fail at the worst point in the season — usually during peak transformer delivery when ambient temperature hits 35 °C and the test bay runs 18 hours a day. The injection MOSFETs in budget units are rated for 25 °C continuous; without a heatsink mass of at least 1.2 kg they thermal-throttle, stretching a 5-second test to 20 seconds and queuing windings on the conveyor.
Enclosure seal matters more than paint. IP54 minimum keeps copper dust and oil mist off the mainboard; IP65 on the floor series survives wash-down in hydro-generator shops. Connectors are silver-plated tellurium copper, rated 10,000 mating cycles — brass-clad alternatives oxidise in humid climates, adding 30 µΩ per cycle after six months.
Calibration Interval Guidance
Annual recalibration is standard for ISO 9001 shops. For 0.05 % class units running >200 tests/day, a six-month interval keeps measurement uncertainty within ±0.07 % — verified by round-robin data from three national labs. Extend to 18 months only if test volume stays below 50/day and ambient is controlled to 23 ± 2 °C.
On-site verification kit (four certified shunts: 1 mΩ, 10 mΩ, 100 mΩ, 1 Ω) lets QA confirm drift between lab visits without shipping the mainframe.
Matching the Product to the Buyer's Need
Motor rewind shops testing sub-1 mΩ armatures need 50 A minimum to overcome thermal EMF noise; 10 A units bury the signal in 2–3 µΩ of thermocouple voltage at the clip junctions. Transformer factories running 110 kV class windings at 2–5 Ω can use 10 A, but benefit from the 0.05 % class to resolve inter-turn shorts that shift resistance by 0.1 %.
Three-phase simultaneous measurement cuts test time 60 % on large power transformers — one clamp set, one button press, three resistances and the balance ratio logged. Single-phase sequential is adequate for distribution transformers under 2 MVA where the balance check is a pass/fail gate, not a trended parameter.
| Application Profile | Recommended Series | Key Option | Typical Lead Time |
|---|---|---|---|
| Motor rewind, armature <1 mΩ | Desktop 50 A | 0.05 % accuracy, 5 m Kelvin leads | 2–3 weeks |
| Distribution transformer <2 MVA | Desktop 20 A | 0.1 % accuracy, MODBUS TCP | 1–2 weeks |
| Power transformer >10 MVA, 3-phase | Floor 100 A | 3-phase simultaneous, OPC UA | 4–6 weeks |
| Hydro generator stator bars | Floor 200 A | IP65, 300 A pulse, extended leads 10 m | 6–8 weeks |
Keeping Repeat Orders Supplied
Stock rotation policy: desktop 20 A and 50 A units hold 15–20 pieces in the bonded warehouse; floor 100 A holds 5–8; 200 A is build-to-order with a 10-week cycle. Blanket orders with quarterly call-offs lock price and reserve slots — last year's peak saw a 14-week gap for unreserved 100 A units.
Spare parts kit (clip sets, fan filters, fuse pack, display protector) ships with every fifth unit at no charge; additional kits are €185 ex-works. Firmware updates are pushed via USB or Ethernet — no licence fee, no subscription. Calibration lab turnaround is 5 working days door-to-door for units under warranty; 3 days expedited for a €220 surcharge.
Private-Label Programme
Minimum 20 units per release for custom silkscreen, boot-logo, and model-number overlay. Tooling amortisation is €1,200 one-time — recovered at 60 units. Firmware skin (colour theme, default language, report header) ships in the same release cycle; no source-code escrow required.
CE declaration and IEC 61010 test report stay under our name; your DoC references our technical file. This keeps your regulatory liability limited to labelling and user-manual translation.
Request a Tooling and Calibration Review
Send your winding spec sheet (voltage class, kVA, resistance range, test volume) and we will return a marked-up configuration with calibration interval, spare-parts list, and landed cost per tester — no obligation.
Start the review →
