What is GR2 0.315 Corona Resistant Enameled Copper Wire?
GR2: This is usually refers to the insualtion with the Grade 2. In Grade 2, the enamel is thicker than Grade 1. Thereby, the dielectric strength and the mechanical protection are higher.
0.315: this is probably the measurement for the diameter of the wire with it being given in millimeters (0.315 mm) which is around 28 in the American Wire Gauge (AWG).
Corona Resistant: This indicates that the wire has been covered with a special type of enamel which is resistant to the effects of partial discharge (also known as ‘corona discharge’). This type of discharge is an electrical phenomenon which occurs at high voltage and can eat away at insulation.
Enameled copper wire: Is a copper conductor insulated with a thin layer of insulation (enamel). It finds its application in transformers, motors, inductors, and for wiring.
Standard, for any drive-output voltage transients above 1 k V peak, with switching frequency above 2 kHz.
Key Specifications & Technical Parameters
| Parameter | Value / Range |
| Bare Conductor Diameter | 0.315 mm |
| Insulation Build | Grade 2 (double build) per IEC 60317 |
| Overall Diameter (max) | standards, customed |
| Enamel Type | Corona-resistant polyamide-imide (PAI) or PAI/PEI hybrid |
| tdermal Class | 180°C, 200°C |
| Elongation at Break | ≥ 25% |
| Volume Resistivity | ≥ 1 × 10¹³ Ω·cm |
| Conductor Temper | Soft-annealed (H0) |
| Standard Compliance | IEC 60317-20 / IEC 60317-43 |
| Spool / Reel Options | 30 kg per spool |
How Corona Resistance Works?
The standard polyester-imide enamel does not survive repeated partial discharges because each PD pulse erodes the organic polymer structure. There is hundreds of switching cycles, pin-holes develop. Resistance of the insulation decreases. Then, dielectric is not able to withstand electric stresses. Winding failure occurs.
GR2 corona resistant enamel interrupts this mechanism in three steps:
Discharge initiation -Voltage spike surpasses the partial discharge inception voltage (PDIV) at a micro-void in the insulation.
Discharge effect rather than destroying the organic polymer, PD plasma interacts with inorganic nano-filler particles, which 2are chemically robust enough not to be attacked by a plasma.
Arrest and redistribution – The nano-particles disperse the discharge energy over a larger surface area, preventing a highly localized erosion point.
The outcome: winding insulation lifetime in PWM-drive circuit to improve 5~10 times with the Grade 2 enamel(BEH). (Offspring depends on the use. Please be sure about test data from the LP Industry.)
Key Properties:
Corona resistant nano-filler matrix -> leads to 40- 60% higher PDIV (partial discharge inception voltage) than conventional enamel directly resulting in longer winding service life in inverter driven systems.
Grade 2 (double-build) insulation -> is a thicker dielectric wall than Grade 1 insulation improves the slot insulation integrity reduces the turn to turn fault probability
Type 200 degreesC thermal rating -> allows for fixed speed motors running at relatively high load to operate continuously without softening of insulation or bond deterioration.
Tight diameter tolerance on 0.315 mm conductor -> Consistent slot fill factor will result in repeatable winding resistance through production.
IEC 60317 compliance -> eases global procurement, CE marking and end customer qualification audits for motor manufacturers.
Soft-annealed copper conductor->has the high flexibility and ductility required for the automatic coil winding at high speed without cracking the conductor.
Applications & Use Cases
A corona resistant Grade 2 0.315 diameter enameled copper wire was produced for use in high d V/dt terminals caused by VFDs, inverters and PWM power electronics. Standard enamels break down in these high d V/dt environments. Corona Grade 2 wire will not.
Specific applications include:
Inverter-duty ac induction motor windings fractional to medium k W range, on VFD outputs up to 690v;
The stator winding of various PMSM such as EV traction and industrial servo motor2.
High frequency transformer windings 10KHz to 100KHz switch frequencies.
Inductive components for switch-mode power supplies.
Aerospace and rail traction motor windings (where 200 OEM thermal class is a design requirement)
Wind turbine generator coils and inverter-coupled voltage transients
Submersible pump motor windings where corona degradation is accelerated by combined thermal and electrical stress.
GR2 Corona Resistant vs. Standard Grade 2 Enameled Wire
| Parameter | GR2 Corona Resistant | Standard GR2 Enamel |
| Enamel formulation | Nano-particle reinforced PAI or PAI/PEI | Standard PAI or PEI |
| Partial Discharge Inception Voltage (PDIV) | ≥ 3,000 V peak (verify) | ~1,500–2,000 V peak (typical) |
| Winding life in PWM drive (relative) | 5–10× longer | Baseline |
| tdermal class | 200°C (Class C) | 155°C–200°C (Class F–C, varies) |
| Mechanical properties | Equivalent | Equivalent |
| IEC standard | IEC 60317-20 / -43 | IEC 60317-8 / -13 |
| Recommended for VFD-driven motors | ✅ Yes | ❌ Not recommended above 2 kHz |
| Cost premium vs. standard | ~10–25% higher | Baseline |
The benefit of windings corona resistance charge is normally recouped after the first prevented warranty repair to an inverter-duty motor. Kitting corona resistant Grade 2 as the standard for production winding processes removes windings field failure as a factor in service-life models.
Compliance & Certifications
IEC 60317 is the international standard for enameled copper winding wire. It defines minimum breakdown voltage, minimum elongation, thermal properties and adhesion. When exporting it is a requirement to meet. This covers EU, Asian and most other markets.
IEC 60317-20 / IEC 60317-43 specific sub-parts describing polyamide-imide and PAI/polyester-imide enameled wires in the thermal class 200degreesC range. (please confirm which specific sub part relates to your supplier‘s product)
IEC 61800-5-1 this standard addressed inverters for adjustable-speed drive systems. Insulation requirements for inverter-duty applications are addressed (including inverter-duty motor windings). GR2 CR wire is the selection of insulation system for meeting this standard‘s dielectric withstand requirements.
IEC 60085 Class C (200 degreesC) — the thermal classification of insulating materials. The class C rating indicates that the enamel maintains its dielectric properties when continuously maintained at a temperature of 200 degreesC.
RoHS / REACH restriction of hazardous substances approval. The majority of GR2 enameled copper wire is RoHS compliant in this size of wire. You should check with your supplier for the declaration of REACH SVHC, when you may require EU product registration.
UL (if applicable) UL 1072 or similar UL certification must be obtained for use of motors in the North American market. Request confirmation of UL listing from individual manufacturer.
Frequently Asked Questions
Q: How can I understand the meaning of “GR2” in 0.315 corona resistant enameled copper wire called GR2 0.315?
GR2 refers to Grade 2 or double-build insulations (IEEC 60317). The wall between two layers of the insulations are coated in several layers which has thicker dielectric-wall incomparison to the grade 1(single build). This grade has the benefits of high breakdown voltage, mechanical protection and abrasion resistance better in automated winding operation.
Q: How do corona resistant and regular enameled wire differ?
Corona resistant enameled wire has inorganic nano-particles ( usually alumina or silica) dispersed in the enamel matrix. These non-conductive nano particles resist erosion by the partial discharge plasma, providing an insulation life 5-10 times that of a normal enamel in inverter driven environments. Enamel without the nano- filler are subject to arc erosion and failure after 1-2 partial discharge cycles in this environment.
Q: Do all the motor windings need to have properly made up? Including the 0.315 corona resistant wire?
Yes. Corona resistant wire is only necessary in the motor winding if it is supplied by inverters, VFDs or other PWM power electronics which generate voltage peaks above about 1 kV p-p and switching frequencies above 2 kHz. Conventional Grade 2 enamel is adequate on line-fed motors.
Q: To which thermal class does the corona resistant enameled copper wire (type GR2 0.315) belong?
In this range, the majority of GR2 corona resistant wires carry a rating of Thermal Class 200 degrees C (Class C in IEC 60085) with a polyamide-imide (PAI) /PEI enamel system. This thermal class rating permits continuous running at a winding temperature of 200 degrees C, which is a requirement for high load inverter duty motors and traction vehicles. The thermal class should be checked from the relevant manufacturer‘s datasheet before final design.
Q: What is the minimum order quantity for GR2 0.315GR2 0.315 corona resistant enameled copper wire?
MOQ‘s differ depending on the manufacturer. Most producers offer this diameter in standard spool weights which could range from 5kg, 10kg or 20kg per reel, and minimums could be anywhere from one to a whole carton (usually 100–200kg). Make sure to contact directly the producer for VO pricing brackets and lead time confirmation (both are variable according to production schedule and stock availability).
Q: What IEC standard is for GR 2 0.315 corona resistant enameled copper wire?
The main standard for component specifications is IEC 60317 Enameled copper winding wire electrical specifications. For corona-resistant wire with a polyamide-imide coating operating at thermal class 200 degreesC then IEC 60317-20 or IEC 60317-43 apply depending on the enamel formulation. IEC 60317 compliance is mandatory for motor manufacturers supplying CE-marked products to the EU market.
GR2 0.315 corona resistant enameled copper wire provides the insulation characteristics mandated by inverter duty motor windings rated dielectric strength, Class C thermal endurance, and partial discharge resilience embedded into each meter of the conductor. If standard spool quantities for production or custom combination or other winding line combinations are needed, our team can specify.