LXLZ Note: This Product Provides Solutions for Parameter Customization And Application.
4-Stage Single Phase EMI Filter Ultra High Attenuation
If you’ve been burned before by EMI filters that just don’t cut it in real-world conditions — noisy equipment, failed compliance tests, or interference creeping into sensitive loads — this is the filter worth taking seriously.
The CW4L4-R series is a 4-stage single-phase AC power line EMI filter built for industrial and commercial applications where standard 2-stage filters simply aren’t enough. Four cascaded LC filter stages deliver ultra-high attenuation across a wide frequency band, making it one of the most effective solutions available for suppressing both conducted and radiated EMI noise on the AC power line.
From the image, the unit features a compact, fully enclosed metal housing with a corrosion-resistant finish — the kind of build quality that holds up in panel enclosures, industrial racks, and OEM machine assemblies. The terminal block interface is clearly visible on the input side, making wiring clean, secure, and suitable for professional panel integration. The label confirms CE and RoHS compliance, which matters if you’re shipping equipment into the EU or working with environmentally conscious end-clients.
Table of Contents
Key Specifications at a Glance
| Parameter | Details |
|---|---|
| Filter Type | Single Phase, 4-Stage EMI Filter |
| Model Series | 25-CW4L4-R / CW4L4-R |
| Rated Voltage | 250V AC (0–250V range) |
| Current Range | 1A – 40A (multiple models) |
| Frequency | 50 / 60 Hz |
| Interface | Terminal Block |
| Housing | Fully enclosed metal shell |
| Certifications | CE, RoHS |
| Operating Temp | -25°C to +85°C |
| Primary Function | Suppress EMI / RFI conducted interference |
What Makes 4-Stage Attenuation Different
Most off-the-shelf filters use 1 or 2 stages. That works fine for light-duty or low-noise environments. But the moment you’re dealing with variable frequency drives (VFDs), switching power supplies, servo systems, CNC controllers, or medical equipment, single or dual-stage filters leave too much noise on the line.
Four cascaded stages means:
- Each stage adds its own attenuation curve — interference that slips past stage 1 gets caught by stage 2, 3, and 4
- Dramatically better suppression in the 150kHz–30MHz range — exactly where conducted EMI compliance testing (CISPR 22, EN55032) gets painful
- Both common-mode and differential-mode noise are addressed simultaneously
- Your downstream equipment — PLCs, sensors, servo drives — operates more reliably with cleaner power
In practical terms, customers running laser cutting machines, medical imaging devices, and industrial automation panels have found that switching from a 2-stage to a 4-stage filter resolved compliance failures they couldn’t fix any other way.
Who This Filter Is Built For
This isn’t a consumer product. It’s designed for:
- OEM machine builders integrating filters into control panels or equipment enclosures
- System integrators working on automation, robotics, or power electronics projects
- Electronics manufacturers needing reliable EMC compliance on production lines
- Industrial equipment distributors sourcing for clients with strict CE/EMC requirements
- EPC contractors specifying power quality components for facility builds
If your procurement checklist includes compliance certifications, current range flexibility, terminal block wiring, and proven attenuation performance — this filter was designed around those exact priorities.
Manufacturing & Supply Advantages
As a direct manufacturer, we offer things that trading companies simply can’t:
- ✅ Full current range coverage (1A–40A) — one supplier for your entire project BOM
- ✅ Custom current ratings and mechanical dimensions available on request
- ✅ Consistent production quality — same components, same testing, every batch
- ✅ CE & RoHS documentation ready for your compliance files
- ✅ OEM labeling available for your brand if required
- ✅ Factory-direct pricing — your margin stays where it belongs
- ✅ Flexible MOQ — we work with serious buyers at various volume levels
Best Practices from the Field
A few things experienced engineers and procurement teams tend to confirm after working with 4-stage filters in real deployments:
- Always match filter current rating to 80% of your circuit’s maximum load — running at or near the rated limit continuously shortens service life
- Mount the filter as close to the panel entry point as possible — long runs of unfiltered cable before the filter defeat the purpose
- Keep input and output wiring physically separated — even a few centimeters of proximity between input and output conductors can couple noise back across the filter
- Use a proper earth ground connection — EMI filters depend on low-impedance ground paths; a floating or high-impedance ground significantly reduces attenuation effectiveness
- For VFD applications, use this filter on the power input side, not between the VFD and motor — the motor-side output of a VFD requires a different type of filter (output reactor or dV/dt filter)
FAQ
Can we get different current ratings under the same model series?
Yes. The CW4L4-R series covers 1A through 40A. Each current rating is a separate SKU. We can provide the full current range from a single order, which simplifies sourcing for projects with mixed circuit requirements. Just send us your current requirements per circuit and we’ll quote accordingly.
Do these filters come with CE and RoHS certificates? Can you provide test reports?
Yes to both. CE and RoHS compliance is standard across the CW4L4-R series. We can provide declaration of conformity and test reports for your compliance documentation. If your customer or certifying body needs specific attenuation data or insertion loss curves, contact us and we’ll pull the relevant data from our testing records.
What’s your MOQ and lead time for bulk orders?
MOQ is flexible depending on the current rating mix. For standard current ratings (6A, 10A, 20A being the most common), we typically maintain stock. For larger or mixed orders, standard lead time runs 7–15 business days. We’ll confirm based on your specific order configuration. OEM/custom orders have longer lead times — discuss early in your project timeline.
Can this filter handle VFD or switching power supply noise specifically?
Yes — this is actually one of the strongest use cases for 4-stage filters. VFDs and SMPS generate high-frequency conducted EMI that standard filters struggle to suppress adequately. The 4-stage design of the CW4L4-R series provides the insertion loss depth needed to bring conducted emissions within CISPR/EN limits. Install it on the AC input side of the VFD or SMPS, with proper grounding.
Is OEM branding available? Can you manufacture under our label?
Yes. We support OEM label printing on the housing. For qualified buyers with sufficient volume, we can discuss fully customized labeling. This is common for system integrators and equipment manufacturers who want a clean, branded finished product. Reach out with your requirements and we’ll discuss the specifics.
Ready to discuss your project requirements? Send us your current rating, quantity, and application details — we’ll get back to you with pricing and availability within 24 hours.