In-line Diameter Gauge & HV Continuity Tester

Selection criteria

Diameter accuracy, test voltage, fault-count resolution.

Supply chain

In-line diameter gauges and high-voltage continuity testers come mostly from European measurement specialists with Shenzhen offices. When approving an enamelled-wire supplier, ask whether every spool is 100 % tested in line and how faults are logged.

Buyer FAQ

What HV continuity test applies and what fault limits are typical?

IEC 60851-5 defines the high-voltage continuity test, with DC test voltages from a few hundred volts to about 3 kV depending on diameter and film grade, and limits expressed as faults per 30 m. Product standards allow a small number of faults, but many motor makers, especially automotive, set tighter in-house limits. State the limit explicitly in your wire specification.

How accurate should the in-line diameter gauge be?

Laser gauges for magnet wire typically resolve about 0.1 µm with accuracy around ±0.5–1 µm; dual-axis heads also detect ovality. Ask for calibration records, the sampling rate and SPC data on overall diameter, with Cpk ≥ 1.33 as a common target. Diameter drift affects slot fill and needle-winder settings directly.

What records should I ask for when auditing a wire supplier?

Ask for per-spool records of diameter trend, fault count and position, line speed and oven temperatures, traceable from spool label to production line and copper batch. Check the rule for spools that exceed fault limits: whether they are scrapped, downgraded or cut. Unlogged manual retesting is a warning sign.

Where it is used