china dc winding resistance tester price - Bulk Supply and Specification Guide

Unit price settles the question only after the test current, measurement range, and calibration traceability are locked to the same revision. A 10 A bench unit with 0.05 % basic accuracy and USB logging costs differently than a 50 A portable with temperature compensation and battery operation, even when both carry the same model prefix.

Material Options and Their Trade-offs

The aluminum chassis dissipates heat from the 50 A current source without fan noise, but adds 3 kg over the ABS unit. For field crews moving between substations, the IP54 convection-cooled model eliminates filter cleaning and survives rain exposure — the clips stay clean longer when stored in the molded recess. Buyers specifying the 36-month calibration interval on the ruggedized unit accept a 22 % price premium for reduced truck rolls.

Size, Weight and Specification Range

Before comparing quotations, align on the measurement span that covers 90 % of your transformers. A 1 μΩ–2 kΩ range with 10 A maximum current handles distribution transformers up to 10 MVA. Adding a 50 A range extends coverage to 100 MVA units but doubles the current-source cost and adds 4 kg.

Display resolution steps at 0.1 μΩ below 1 mΩ, 1 μΩ to 100 mΩ, and 10 μΩ above. The mid-range unit stores 10,000 readings with timestamp and winding ID; the entry model holds 500. Ethernet and Wi-Fi are factory options on the top two tiers — retrofitting requires mainboard replacement.

Quality Control and Batch Consistency

Two suppliers quoting the same specification often diverge on lot-to-lot repeatability of the current-source linearity. Our line runs a 12-point verification at 0.1 A, 1 A, 5 A, 10 A, 20 A, and 50 A against a 0.005 % standard resistor bank before each shipment. Units exceeding ±0.015 % deviation at any point are pulled for rework — typically 2–3 % of production.

Each shipment includes a batch certificate listing the serial-numbered linearity plot and thermal soak result. Buyers who re-certify annually report fewer warranty returns when they archive these plots and trend the 10 A point — a 0.008 % shift over 18 months predicts calibration failure before the due date.

Stock Availability and Reorder Planning

The entry bench model ships from Shenzhen within 5 business days for orders up to 20 units. The mid-range portable carries a 15-day lead at 10 units; the high-current field unit runs 25 days due to the 50 A current-source burn-in. Blanket orders with quarterly releases lock the price and pull lead time to 7 days for all tiers.

Firmware updates ship on USB-C drives packed with each unit; the mid-range and high-current models support OTA via Ethernet. Specify the firmware revision at order placement — revision 3.2 added the IEEE C57.12.90 test sequence macro that saves 4 minutes per transformer.

Export Packaging and Handling Protection

Each tester ships in a double-wall corrugated carton (ECT 48) with die-cut polyethylene foam cradling the instrument and a separate compartment for the lead set. The high-current model adds a shockwatch 25 G indicator and a humidity card — units showing activation or > 60 % RH are quarantined for full re-verification before release.

• Palletized 4 units per layer, 3 layers max, stretch-wrapped with edge protectors
• Desiccant packs calculated at 1 unit per 0.03 m³ carton volume
• Labeling: CE mark, WEEE symbol, serial barcode, and "Precision Instrument — Do Not Drop" in EN/ZH/ES
• Customs HS code 9030.31 declared on commercial invoice with country of origin

Distributors re-exporting to the Middle East should request the conformal-coated PCB option — salt-fog testing shows 40 % longer creepage life on the current-source board. The coating adds 3 days to lead time and 1.8 % to unit cost but eliminates the leading cause of field returns in coastal humidity.