Insulating colorants give copper busbars, IGBT modules, and charging power modules both phase identification and dielectric protection. This article presents three field application cases with measured process and electrical data, showing how carrier selection and dosage control the finished insulation performance. DENSON insulating colorants from Dongguan DENSON Functional Materials Co., Ltd. are matched to epoxy, silicone, and polyurethane systems.

1. Introduction

In new-energy electrical equipment, color is functional: it identifies phases, indicates impregnation coverage, and supports traceability. But the pigment must not introduce conductive impurities or voids. Across the three cases below, the controlling factors were the colorant carrier, the coating or potting process, and vacuum degassing. See the DENSON EP colorant series for carrier-matched grades.

2. Technical Features and Mechanism

An insulating colorant is a concentrated pigment dispersion carried in an insulating resin. Phase colors follow GB/T 2681: phase U yellow, phase V green, phase W red, neutral N light blue, and protective earth PE in a yellow-green combination. The carrier must match the host resin to avoid flocculation.

3. Case Study 1: Epoxy Powder Coating of Switchgear Busbars

A switchgear maker coated copper busbars with epoxy powder in a fluidized-bed process. Bars were preheated to 180–220 °C, coated to 0.4–1.0 mm, and cured at 180 °C for 20 min. The coated bars passed a 42 kV/1 min power-frequency withstand test and 720 h salt spray.

Fig.1 Phase-colored epoxy-coated busbars (finished product)

4. Case Study 2: Epoxy Potting of an IGBT Module

A power-module manufacturer preconditioned parts A and B at 60 °C for 60 min, mixed them, and degassed below 1100 Pa before filling an EconoPACK-style module (about 110×57.5×17 mm). The potted module reached volume resistivity 3.4×10¹⁵ Ω·cm, dielectric strength 23 kV/mm, and CTI ≥400, and it survived 100 thermal cycles from -40 to 125 °C.

Fig.2 IGBT modules before and after epoxy potting (process)

5. Case Study 3: Silicone Potting of a 120 kW Charging Module

A charging-infrastructure maker used a thermally conductive silicone for a 120 kW module. The compound reached thermal conductivity 1.0 W/(m·K), UL 94 V-0, and IP65, and passed 1000 h at 85 °C/85% RH, protecting the electronics from moisture and vibration.

Fig.3 Silicone potting inside a charging power module (finished product)

6. Key Selection Parameters and Recommendations

Recommendation: choose epoxy carriers for busbars and IGBT modules, silicone for thermally stressed charging modules, and always degas below 1100 Pa. More options are on the DENSON website.

7. Conclusion

Across busbars, IGBT modules, and charging modules, insulating colorants delivered phase identification while maintaining dielectric strength of 20–23 kV/mm and volume resistivity above 10¹⁴ Ω·cm. Carrier matching, controlled thickness or filling, and vacuum degassing were the decisive process factors.

8. FAQ

Q1: Which phase colors are used for insulated busbars?
Per GB/T 2681, phase U is yellow, phase V is green, phase W is red, the neutral conductor N is light blue, and the protective earth PE uses a yellow-green combination. These colors support correct wiring and maintenance.

Q2: What coating thickness is typical for epoxy-coated busbars?
A typical epoxy powder coating on switchgear busbars is 0.4–1.0 mm thick, applied after preheating to 180–220 °C and cured at about 180 °C for 20 min; coated bars commonly pass a 42 kV/1 min withstand test per GB/T 11022.

Q3: Why is vacuum degassing important in IGBT potting?
Vacuum degassing, typically below 1100 Pa, removes air bubbles that would otherwise form voids. Voids concentrate the electric field and reduce dielectric strength, so degassing is essential to reach values such as 23 kV/mm and low partial discharge.

Q4: Which potting material is preferred for charging power modules?
A thermally conductive silicone is commonly preferred for charging modules because it combines thermal conductivity around 1.0 W/(m·K), UL 94 V-0 flame rating, IP65 sealing, and endurance under 85 °C/85% RH damp-heat conditions.

Q5: Can one insulating colorant be used in all resin systems?
No. The colorant carrier must match the host resin—epoxy, silicone, or polyurethane—to prevent flocculation and separation. A 48-hour compatibility test should show no flocculation before the colorant is adopted.