MPP vs MPET Capacitor – Key Differences, Applications & Selection Guide

When selecting film capacitors for industrial or power electronic applications, engineers often compare MPP (Metallized Polypropylene) and MPET (Metallized Polyester) capacitors.

While both are metallized film capacitors, their electrical performance, thermal stability, and application suitability differ significantly.

This guide explains the technical difference between MPP and MPET capacitors to help engineers choose the right one.

1️- What is an MPP Capacitor?

MPP stands for Metallized Polypropylene capacitor.

It uses:

• Polypropylene dielectric film
• Vacuum metallized electrode layer
• Self-healing construction

Key Characteristics:

• Low ESR
• Low dielectric loss
• High ripple current capability
• Excellent frequency stability
• Better temperature performance
• Long lifespan

MPP capacitors are widely used in:

• DC link circuits
• IGBT modules
• Snubber circuits
• High-frequency inverters
• EV power electronics

2️- What is an MPET Capacitor?

MPET stands for Metallized Polyester (PET) capacitor.

It uses:

• Polyester dielectric film
• Metallized electrode layer

Key Characteristics:

• Higher dielectric constant
• Compact size for same capacitance
• Higher ESR than MPP
• Moderate ripple capability
• Lower cost

MPET capacitors are commonly used in:

• Fan regulators
• Motor run circuits
• Lighting circuits
• Consumer electronics
• EMI suppression

3️- MPP vs MPET – Technical Comparison

4️- Why MPP Has Lower ESR than MPET?

Polypropylene has:

• Lower dielectric loss factor
• Higher insulation resistance
• Better thermal dissipation

This results in:

✔ Lower self-heating
✔ Higher ripple current capability
✔ Better performance in high-frequency circuits

This is why MPP capacitors are preferred for DC link and IGBT applications.

5️- Application-Based Selection Guide

Choose MPP When:

• High ripple current is required
• Low ESR is critical
• Application involves EV / inverters
• Long life is required
• Operating temperature is high

Choose MPET When:

• Cost optimization is required
• Compact size is important
• Application is low-frequency
• Moderate performance is acceptable

6️- Reliability & Lifespan Comparison

MPP capacitors generally provide:

• Better thermal endurance
• Lower capacitance drop over time
• Reduced internal heating

MPET capacitors, while cost-effective, may have:

• Slightly higher dielectric losses
• Higher self-heating under load

For mission-critical applications, MPP is preferred.

7️- Frequently Asked Questions

1. Is MPP better than MPET?

For high-performance power electronics, yes.
For cost-sensitive consumer applications, MPET may be sufficient.

2. Which capacitor is better for DC link?

MPP capacitor.

3. Which capacitor is used in fan motor?

Typically MPET or motor-run polypropylene depending on rating.

8️- Final Conclusion

Both MPP and MPET capacitors have specific advantages.

MPP capacitors are ideal for:

• High ripple
• High frequency
• EV and inverter systems

MPET capacitors are suitable for:

• Consumer appliances
• Cost-sensitive applications
• Moderate electrical stress

Selecting the correct dielectric directly impacts system reliability and performance.