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Please advise on Cheap Conducted EMC test setup for offline SMPS's
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ocset:
Please help advise about the  very basic  conducted EMC test setup for offline SMPS’s,   on figure 6, page 3 of AN15 by power.com.

This setup is obviously a cheap compromise,  since the test setup in figure 6 is not as complete as in an accredited test house, the conducted EMC scans will  therefore be discrepant.
What will be the main nature of this discrepancy? Up to what frequency will the setup of Figure 6 be accurate?

Page 3, figure 6,  of AN15 shows a conducted EMC emissions setup for an offline SMPS (figure 6). It says that 6 foot cables  should be used between the unit under test and the LISN, and the UUT and the load....but in the picture they dont look like 6 foot cables, they look much shorter...can this be "six foot" be right?

Also, it seems to be saying that the table is up against a vertical "reference plane" which is 2m by 2m. Presumably this reference plane is just a floating piece of metal sheet?

The LISN must be bonded to this metal plane. I thought that the LISN should be right up against the reference plane, so that the LISN's connection to the reference plane can be as short as possible? –But in Figure 6, the LISN seems to be 40cm away from the reference plane….surely this can’t be right?

Also, i thought that the table should have a metal sheet beneath it aswell as the one at the end of it?

Also, where does the spectrum analyser go in this setup?..presumably it connects to the LISN via a coaxial cable..and the specturm analyser is  at least 2 metres away from the unit under test?

AN15
https://ac-dc.power.com/design-support/product-documents/application-notes/an-15-topswitch-power-supply-design/

coppercone2:
the cheapest way is to hide it in someone else's product
TimNJ:
First off, the conducted EMI test setup is quite forgiving in comparison to the setup required for radiated EMI. By that I mean, your exact setup probably doesn't matter too much. You will likely get reasonably close results. Just give yourself a little margin. 10dB is a nice number.

Where I work, we have a horizontal reference plane on the floor, made of an aluminum sheet, bonded to local earth connection. On top of the reference plane we have a short wooden table, which we place the DUT on. On a separate, normal height wooden table, we have the spectrum analyzer, PC, and LISN. Use a low-inductance connection to bond the LISN to the reference plane below. (Braided ground strap is a good choice.) In our case, the strap is relatively long, but results are still accurate. (Would advise against using long piece of wire, though. Inductance is too high.) You can keep the spectrum analyzer, PC, and LISN relatively close to each other. Just make sure you have some distance between those devices and the DUT, about 80cm recommended. Make sure the cable connecting between the DUT and the LISN does not dangle too close to the floor. Bundle non-inductively, if you must. 1m cable is typical.

Also helps to solidify the earth connections between the LISN and spectrum-analyzer frame. You can put clamp-on ferrites on PC cables for the monitor, power, etc.
ocset:
Thanks
We believe that the DSA815 specturm analyser is the cheapest in the world for our purposes (rough conducted emissions test for offline SMPS)....

DSA815 spectrum analyser
https://www.rigolna.com/products/spectrum-analyzers/dsa800/

Regarding the LISN, we believe that the Hameg HM050 is the cheapest on the market.....

Hameg HM6050 LISN
http://www.farnell.com/datasheets/1851611.pdf?_ga=1.216594710.1679746183.1489787856


We find that the total cost is going to be £4022…..

DSA815 spectrum analyser = £1300
Including the following necessary options for DSA815 spec analyser..
-Advanced Measurment kit (AMK-DSA800) = £423
-VSWR-DSA800 = £400
-EMI-DSA800 = £454
S1210 EMI pre-compliance software = £450

HAMEG HM6050 LISN = £1000


….however, we realise that we are going to also need to buy transient limiters (to protect the spectrum analyser input) and a broadband  RF power amplifier for the connection from LISN to spectrum analyser. Does anyone know how much these  are and can recommend cheap ones  to buy?

Also, do you think we can get away with just a one metre square aluminium ground plane?
Also, do you know what is the difference between having a vertical ground plane, and a horizontal ground plane? (we appreciate that in official  EMC test houses for conducted EMC, the entire room is shielded, but we cant afford that)
Niklas:
Do you really need the AMK-DSA800 and VSWR-DSA800 packages for your conducted emissions setup?
The DSA815 also has a built in pre-amp, so you start with that.
It is possible to run the DSA815 in standalone mode without the PC software.
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