Due to the nature of the EMC chamber, all conductors passing through the shield need to do so in a controlled manner to ensure that conducted and radiated emissions do not interfere with the quiet environment/ test conditions created within the chamber. In order to achieve this any power or data cables which pass into the shielded chamber need to do so through an EMI Filter.
Generally, EMI filters consist of passive components which are connected together to form LC circuits. The LC circuits allow DC or low frequency currents to pass through, whilst ushering the higher frequency, unwanted currents down a low impedance path and into the ground/ earth connection leaving the clean/ quiet environment within.
NTD Shielding Services supply high performance filters that are ideal for this application and are designed to meet the very highest insertion loss requirement of 100dB from 10kHz to 10GHz and features an extended low frequency performance to provide considerable filter attenuation at frequencies as low as 1kHz.
Power Filters are available in both single phase and three phase as per the table below.
General Specification – EMI Power Filters
| Rated Voltage | |
| Single Phase Filters |
250V a.c. 50/60Hz Also suitable for 277V a.c. 50/60Hz and 2 line d.c. supplies up to 600V d.c. (with alternative varistors if transient suppressed) |
| Three Phase Filters |
250/440V a.c. 50/60Hz Also suitable for 277/480V a.c. 50/60Hz (with alternative varistors if transient suppressed) |
| Rated Current | See table below |
| Insertion Loss | 100dB from 10kHz to >10GHz |
| Maximum Temperature Rise on Full Load | 25oC |
| Ambient Temperature Range | -45oC to +85oC |
| Maximum Full Load Heat Dissipation | See table below |
| Operating Temperature Range on Full Load | -45oC to +50oC |
| Maximum Volt Drop per line at Full Load d.c. | 500mV |
| Current Discharge time to below 34V | 30 seconds MAX |
| Single Phase (+N) | Part Number | Volt Drop (mV) | Heat Dissipation (W) | Major Dimensions (mm) | Approx Weight (kg) | ||
| A | B | C | |||||
| 6 | NSF-6 | 500 | 8 | 310 | 175 | 90 | 8 |
| 10 | NSF-10 | 500 | 11 | 310 | 175 | 90 | 8 |
| 16 | NSF-16 | 500 | 15 | 550 | 205 | 95 | 16 |
| 32 | NSF-32 | 500 | 25 | 550 | 205 | 95 | 18 |
| 63 | NSF-63 | 500 | 52 | 640 | 205 | 120 | 22 |
| 100 | NSF-100 | 500 | 60 | 660 | 475 | 135 | 60 |
| 200 | NSF-200 | 500 | 120 | 750 | 500 | 160 | 75 |
| 400 | NSF-400 | 500 | 160 | 1050 | 525 | 185 | 110 |
| Three Phase (+N) | Part Number | Volt Drop (mV) | Heat Dissipation (W) | Major Dimensions (mm) | Approx Weight (kg) | ||
| A | B | C | |||||
| 6 | NTF-6 | 500 | 12 | 310 | 350 | 90 | 16 |
| 10 | NTF-10 | 500 | 16 | 310 | 350 | 90 | 16 |
| 16 | NTF-16 | 500 | 25 | 550 | 410 | 95 | 22 |
| 32 | NTF-32 | 500 | 48 | 550 | 410 | 95 | 24 |
| 63 | NTF-63 | 500 | 70 | 660 | 410 | 135 | 45 |
| 100 | NTF-100 | 500 | 70 | 660 | 575 | 150 | 70 |
| 200 | NTF-200 | 500 | 120 | 750 | 700 | 170 | 95 |
| 400 | NTF-400 | 500 | 240 | 1700 | 700 | 170 | 200 |
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NTD Shielding’s EMI power filters are specifically engineered to maintain the controlled test environment required for EMC compliance. Whether you’re working with single-phase, three-phase, or high-current applications, our filters deliver robust performance across a wide frequency range. With reliable attenuation starting as low as 1kHz and extending well beyond 10GHz, they’re ideally suited to demanding EMC test and research settings. We also supply data line filters, signal line suppression, and custom solutions for complex installation requirements, ensuring your entire chamber remains fully shielded against unwanted interference.