When do you apply EMC glands?
To answer this question we first have to define EMC or EMI: EMC is the short form of ElectroMagnetic Compatibility, EMI means ElectroMagnetic Interference. According to EU guidelines EMC is defined as “to limit the electromagnetic emissions for equipment in order to ensure that, when use as intended, such equipment does not disturb radio and telecommunication, as well as other equipment and additionally such equipment is immune to interferences and is not disturbed by radio emissions”. Such electromagnetic (EM) disturbances can occur whenever systems are driven by alternating current and/or controlled by frequency modulated signals. Such systems nowadays are used for high efficient production lines. The disadvantage coming alongside is electromagnetic smog which has to be avoided by suitable and cost-effective means.
The only reasonable remedy against EM smog will be a totally EM-shielded system! This shielding will start at the electronic board, will be continued by a conductive housing/box and screened cables. As these cables could act as active or passive antenna their outer sheath must also be an integral part of the earthing system. Normally this is done by a cable gland or a connector. In both cases the electrical connection should show low impedance. This is to ensure high damping up to high frequencies in the GHz-regime.
For this reason EMC cable glands will be used: they realize electromagnetic connection between cable sheath and electrical ground of the housing. Such a closed Faraday cage will fulfill the above mentioned EU guideline – there will be no electromagnetic smog!
Our Euro-Top EMC cable glands are coming with four unique features:
- Superb damping rate up to very high frequencies
- Strain relief according EN 62 444
- Protection against dust, moisture and water according IP 66, IP 68, IP 69 and NEMA 4X
- Easy installation and handling
Figure 1 shows the damping rate of our Euro-Top EMC3 and EMC4 depending on frequency. The limiting device of these tests was the control cable used!
Our patented EMC system inside the gland guarantees a low impedance contact. It is designed to perform excellent even under harsh environmental conditions without fading during the complete lifetime of the system. Simultaneously our EMC glands can easily be installed without disassembling it.
Production lines are getting more and more challenging to improve production efficiency. Therefore powerful frequency modulated technics are used. In a lot of cases these technics induce parasitic, high amperage alternating EM currents into the cable screens. Among others such technics are PWM (Pulse Width Modulation) and VFD (Variable Frequency Drive). Electrical currents up to several hundreds of Amps could occur this way and must therefore securely be grounded. For such high currents normal EMC glands will fail. For such applications we developed our Euro-Top EMC Ampacity cable gland which adds another feature to the above mentioned:
- Carries high current load
This was realized by increasing the contacting cross-section between cable sheath and cable gland. Although this was a tremendous additional challenge it doesn’t neither impact the excellent shielding characteristics nor the easy handling.