Polyester Overcoated With Polyamide-Imide Enamelled Aluminium Wire

Class 220 is not the "better" version of Polyester(imide) Overcoated with Polyamide-Imide Enamelled Aluminium Wire, Class 200, and buying it by default is how money disappears from a bill of materials. It exists for one situation: a design where the calculated hot spot genuinely passes 200 °C and the only alternatives are a bigger core, a bigger enclosure or forced cooling that the customer will not accept.

This wire - EI/AIW/220, type Q(ZY/XY)/L, GB/T 23312.7, IEC 60317-25, NEMA MW 35-A - is the same two-layer construction as Polyester(imide) Overcoated with Polyamide-Imide Enamelled Aluminium Wire, Class 200 with a film system rated 20 K higher. Same conductor range, 0.20–6.00 mm. Same spools. The difference is only visible in the calculation and on the label.

What 20 K actually buys

 

A smaller core and tank at the same rating

If the permitted hot spot rises by 20 K, the losses the design can afford rise with it, and for a fixed cooling surface that means less iron and less copper - or, here, less aluminium. On a high-power-density transformer this is the whole commercial case. The metal you remove is worth more than the wire you upgrade.

Operation in an enclosure with no air movement

A reactor or transformer inside a sealed cabinet has conduction and radiation only. The winding sits where a ventilated design would never allow, and the calculation cannot be argued down by adding a fan that the enclosure does not have room for.

Tolerance of a high ambient design point

Rooftop, desert, tropical plant room, solar inverter cabinet in direct sun. When the ambient design point is 50 °C or above, 20 K of extra class is 20 K of load the unit can still carry.

Where it is specified

High-power-density transformers

The case is downsizing under a fixed enclosure. Distribution and small power transformers designed to run hot - because the customer wants the mass, the footprint or the cost out - land on class 220 when the hot-spot calculation refuses to close at 200 °C. The wire is the last component to become the constraint, which is why it is specified last and costs least in the sequence.

Dry-type units at class 220 sit above the designs on Class 180 Polyesterimide Enamelled Aluminium Round Wire (class 180, open-wound ventilated) and Polyester(imide) + PAI enamelled Al (class 200, cast-resin). If your winding is air-cooled with visible windings and a hot spot under 180 °C, none of these three pages is your answer -Class 180 Polyesterimide Enamelled Aluminium Round Wire is.

Inverter, reactor and PV / wind magnetics

An inverter reactor is the clearest case for this product in the renewable segment. Harmonic current concentrates loss, the enclosure is sealed against dust and weather, ambient inside a cabinet runs well above outdoor temperature, and the reactor has to ride through grid faults that push current far above rated for a few seconds.

A PV or wind converter cabinet is a hostile thermal environment for any winding: no forced air, high common-mode stress, continuous thermal cycling with the resource. Class 220 with a hard polyamide-imide surface is the practical specification when the reactor cannot be made bigger.

Severe-duty and explosion-proof motors

Motor windings in explosion-proof enclosures, high-temperature process areas, or machinery that is started and stalled repeatedly. The winding is thermally trapped by the enclosure and mechanically worked by the duty cycle; class 220 gives back the margin the enclosure took away.

Where the motor is aluminium-wound by design - weight-critical, or a market where aluminium is the established practice - this is the highest class available on aluminium in our range. Above it, Enamelled Aluminium Round Wire, Class 240 changes product family entirely and is built for voice coils, not motors.

Application

For motor

For transformer

Specification

Caption: Class 220 enamelled aluminium wire (EI/AIW/220, Q(ZY/XY)/L) - two-layer construction, 0.20–6.00 mm.

 

Item	Specification
Type designation	EI/AIW/220 - Q(ZY/XY)/L
Thermal class	220 - Class C
Standard	GB/T 23312.7, IEC 60317-25, NEMA MW 35-A
Construction	Polyester(imide) base + polyamide-imide overcoat
Conductor	Aluminium, round, annealed
Size range	0.20–6.00 mm
Properties	Thermal stability, high temperature resistance, high heat shock resistance, high mechanical strength
Enamel build	Grade 1, 2, 3
Enamelling passes	10–13, two-coat system
Spools	PT-25, PT-30, PT-35, PT-60, PT-90, PT-200, PT-270, wooden spool or customized on request
Typical applications	High-power-density transformers, inverter and reactor magnetics, PV and wind converter cabinets, severe-duty and explosion-proof motors

 

Test schedule for every batch

Every delivery is accompanied by a batch test report. These are the tests it covers, and the limits applied are those of the standard quoted above:

Group	Tests performed
Conductor	conductor diameter and tolerance, elongation, springback
Film	enamel build, continuity of covering, flexibility and adherence, heat shock, cut-through, scrape resistance, adhesion
Electrical	breakdown voltage, electrical resistance, tangent delta
Chemical	solvent resistance; refrigerant resistance where the application requires it

The values are diameter-dependent, so they belong on the report for the size you buy rather than in a generic table. Ask for a sample report at your diameters before the first order.

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