Built to last HILO Test CDN-208

06 Jun,2022

06,Jun,2022

Built to last HILO Test CDN-208

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We’ve brought ‘Fix It Friday’ forward to Wednesday here at the Equipment Calibration Business with the repair of an old but very well made, built to last HILO Test CDN-208.

Our main benefit to customers and one that sets us above the competition is our on-site UKAS accredited calibration service, saving customers significant down time whilst maintaining really competitive costs.

We also repair a whole host of Surge, Transient and ESD equipment, amongst others. This afternoon’s repair was a HILO-Test CND-208. This is for unshielded unsymmetrical interconnection lines and is probably 25+ years old, a real workhorse! Fault finding on this was easy with four really bulged inductors each measuring less than 3 mH - they should be 20 mH.

EN61000-4-5: 2006 specified a value of 20 mH for the inductor/choke in this CDN, the later revision (2014) removed the 20 mH requirement but the CDN must provide the correct output with the AE side of the CDN connected to ground. When selecting an inductor to fit the bill, two key parameters need to be covered. Core saturation and inductance value. The inductance realistically needs to be 10 mH or greater and the core should be iron (not ferrite).

This CDN has a relatively low current capacity and coupling lines 1-4 had been abused with current high enough to fuse the windings in the inductors. The new inductors are 15mH and have a greater current handling and give a good low residual voltage at the AE port.

Given the propensity of EMC Engineers to damage and abuse test equipment, it’s a testament to HILO-Test that this is the first major repair!