Do you remember why this is so? If not, our article Why do we need a power line filter and where to place it? will remind you.
At present, almost any mains operated device uses a switched power supply. It is well known that the additional costs associated with adapting the final equipment due to non-compliance with EMC requirements are significantly higher than the costs incurred for EMC during the development of the equipment.
The experienced designer, therefore, considers the EMC requirements from the start of the design and designs the device so that a power entry module without EMC filter or with EMC filter can be used without modification of the device.
Even though the probability that the device meets the requirements for electromagnetic compatibility without additional EMC filter is low, the power entry module without EMC filter is significantly less expensive than a module with filter. Its use is therefore worth considering.
Schurter offers the power entry modules DD11 (without EMC filter), DD12 (with single-stage EMC filter) and DD14 (with two-stage EMC filter) for this scenario. The modules can be mounted in the same panel cut-out, the spacing of the panel mounting holes is the same, and therefore no additional panel adjustments are necessary.
Modules differ in-depth, while DD14 with two-stage EMC filter is only 5mm longer than DD12 with one-stage EMC filter. The designer considered the length of the modules when designing the equipment; no additional modifications to the equipment are necessary.
Model Example
Our PC uses a 150W switched AC/DC power supply. Let's look at how it complies with the EMC requirements for information technology equipment (ITE) according to EN 55022/32, Class B (equipment intended primarily for use in a residential environment) when using the DD11, DD12 and DD14 modules.
EN 55022/32 defines limits for conducted emissions with quasi-peak and average signal detectors over the applicable frequency range of 150kHz to 30MHz. Both limits must be satisfied.
From the measured results it is clear that our equipment did not meet the requirements.
Conducted emissions are significantly lower, but limits are still exceeded.
Our equipment complies with sufficient margin; we have found a solution.
For further information about Schurter products, please do not hesitate to contact us at schurter@soselectronic.com.
- all modules have a two-pole switch
- one or two fuse holders 5x20mm
- quick-connect terminals 6.3x0.8mm (DD11 4.8x0.8mm)
- meet safety requirements for ITE according to IEC 60950 and medical equipment according to IEC 60601-1.
- compatible with V-Lock system to prevent unintentional disconnection of the power cord
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