KROHNE MFC 010 C Converter - Manual (Page 99)

MFC010 Interface Manual 97
Appendix E : Installation of Power Supplies in MFC010 Applications
Application Note
Connection of Power supplies in MFC010 Applications
The MFC010 is a self contained Mass flow measurement converter which requires an ex ternal 12V DC
input supply. I n many applications, a dedi cated off the shelf power supply will be us ed. I n these cases
careful not e s hould be m ade t o t he E MC c ompliance of the power supply chosen. Many off the shelf
power supplies are c ertified t o C lass B c ompliance, w here t emporary degr adation of per formance i s
permitted when Electromagnetic Interference is present. However, degradation in the performance of the
power supply may have an undue influence on the operation or performance of the MFC010.
To maintain MFC010 operation within specification it is advised to comply with the following suggestions
when installing EMC Class B certified power supplies.
i) ALWAYS install the power supply in a properly Earthed METAL enclosure
ii) Connect suitable Y Class suppression capacitors (such as t he V ishay W KP or W KO t ype )
from each power supply input terminal to a robust Earth connection.
iii) Connect a suitable Y Class suppression capacitor (such as the Vishay WKP or WKO type )
between the 12V output terminals of the power supply.
iv) Fit a suitable ferrite (such as a 74271132 from Würth Elektronik) to the cable immediately after
the power supply output terminals.
All of the capacitors should be f itted in as close proximity to the Power supply terminals as is possible,
ideally at the terminals themselves.
The t wo t ypes of pow er s upply av ailable f rom K ROHNE, 85 -265VAC input and 20-72 VDC input, are
supplied with the recommended suppression capacitors. T he MFC010 has been t ested and certified for
EMC compliance using these power supplies in association with the supplied capacitors. The following
pages indicate the actual terminals of each power supply to which these capacitors should be fitted.
Power s upplies t hat c onform t o C lass A oper ation should not require further EMC suppression
components, but should be housed in a suitable enclosure. C are must always be t aken when installing
such c omplex el ectrical s ystems as poor i nstallation can l ead t o degr aded s ystem per formance,
regardless of how well designed and certified the individual components are.