Polyester Enamelled Aluminium Round Wire

Two thermal ratings, one enamel system, one production line. PEWA130 and PEWA155 are the same modified polyester enamel on the same aluminium conductor - the 155 version uses a resin modification that lifts the continuous rating by 25 K. Everything else, from the 0.20–6.00 mm size range to the spool programme, is identical.

That is deliberate. It means a customer building both a class 130 fan motor and a class 155 pump motor can buy one product family, hold one set of incoming inspection limits, and change the thermal class with a single field on the order.

What the aluminium conductor changes

An aluminium winding needs roughly 1.6 times the cross-section of a copper winding for the same resistance, and weighs about half as much. In a distribution transformer that trade converts into a lighter core-and-coil, a lighter tank, and a lower transport cost. In an appliance motor it converts into a stator designed around a larger slot.

Either way the enamel meets a different mechanical regime than it would on copper. Aluminium is softer; it deforms more under winding tension, and the film takes more of the load at every bend. That is why this product is normally specified at grade 2 build rather than grade 1 - the extra film thickness is mechanical protection, not dielectric margin.

Where "modified" earns its place

A straight polyester enamel is a class 130 material. Reaching 155 without changing the application process means modifying the resin so the cured film resists thermal degradation for longer at the higher temperature. The catalogue properties for both ratings are the same: good heat resistance, abrasion resistance, good adhesion.

In service the three properties map onto three failure modes:

Heat resistance - the winding survives the continuous hot spot, and the varnish bake afterwards.

Abrasion resistance - the film survives the guides, the felt and the slot entry during winding.

Adhesion - the film stays on the metal when the wire is bent at the lead, which is where most turn-to-turn faults begin.

Construction and dimensions

Dimension limits per IEC 60317-0-3. Extract at four reference diameters (mm):

The gap between G1 and G3 on a 1.00 mm conductor is 0.061 mm per turn - over 1.2 mm on a twenty-layer coil. That is the number to check against your winding window before you fix the build grade.

Electrical and mechanical characteristics

Why each row matters to a designer

Elongation is measured on the annealed conductor, not on the finished wire, and it is the number that decides whether the wire survives being drawn down and then bent. Aluminium is softer than copper, so this is the first figure a motor designer asks for - and the first one an incoming inspection department tests.

Springback governs coil forming. A higher springback angle means the coil opens after the winding head releases it, which shows up as a loose coil and a slot-fill problem rather than as a wire fault.

Breakdown voltage is quoted by build grade because the three grades differ in film thickness, not in enamel quality. Specify the grade, then read the voltage.

Cut-through is the property that decides whether the winding survives a short circuit. It rises with thermal class, which is the real engineering difference between the 130 and 155 versions - not just a label.

VIdeo

 

Aluminium instead of copper: where the money actually is

Three arguments bring buyers to PEWA, and they are not equally strong.

Material cost and copper price exposure. Aluminium converts at a lower cost per unit of conductance, and it decouples the bill of materials from a metal whose price moves faster than most purchasing departments can hedge. For a transformer builder working to a fixed-price contract, that predictability is often worth more than the saving itself.

Mass. Roughly half the weight for the same resistance. On a distribution transformer that cascades: lighter core-and-coil, lighter tank, lighter transport, lower erection cost. On a pole-mounted unit it can decide whether the installation is a two-man job or a crane job.

Process compatibility - with conditions. The winding equipment and the enamelling route do not change. What does change, and has to be planned:

Tension settings. Aluminium is softer and deforms more, so a tension that suited copper will over-strain it.

Springback. Different from copper, so coil-forming tooling may need adjustment.

Slot geometry. If you keep the same rating, the slot must accept about 1.6 times the conductor area. That is a design change, not a settings change.

Termination. Aluminium is brazed, not soldered. A line set up for solder joints needs a process step added.

Saying this plainly costs us the occasional order from a buyer who wanted a drop-in replacement. It saves the customer a failed first build, which is worth more.

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