Difference between revisions of "EMI suppression cores"
From Granite Devices Knowledge Wiki
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| − | [[File:Ferrirebeads.jpg|thumb|Snap on ferrite beads]] | + | [[File:Ferrirebeads.jpg|thumb|Snap-on ferrite beads]] |
[[File:Ferritebead.jpg|thumb|Toroidal ferrite bead]] | [[File:Ferritebead.jpg|thumb|Toroidal ferrite bead]] | ||
| − | EMI suppression cores a.k.a. ferrite beads are an efficient way to reduce high frequency interference from wiring. Adding ferrute beads to signal & power wiring is recommended if signal reliability problems are encountered. | + | EMI suppression cores a.k.a. '''ferrite beads''' are an efficient way to reduce high frequency interference from wiring. Adding ferrute beads to signal & power wiring is recommended if signal reliability problems are encountered. |
==Selection== | ==Selection== | ||
For motor control applications it is recommended to get low to medium frequency ferrite beads for maximum efficiency. | For motor control applications it is recommended to get low to medium frequency ferrite beads for maximum efficiency. | ||
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*Core material designed for low to medium frequency bands (attenuation between 1-300 MHz) | *Core material designed for low to medium frequency bands (attenuation between 1-300 MHz) | ||
*Large enough to fit cable multiple rounds through it | *Large enough to fit cable multiple rounds through it | ||
| − | ;Avoid | + | ;Avoid |
*Core material designed for high frequency bands (above 300 MHz) | *Core material designed for high frequency bands (above 300 MHz) | ||
*Inductor cores - will just add inductance and make things worse | *Inductor cores - will just add inductance and make things worse | ||
*Iron powder cores | *Iron powder cores | ||
| + | ==Where to find suitable cores== | ||
Most ferrite & iron powder cores look same. So if unsure about material properties, its most safe bet to purchase low to medium frequency beads from distributors such as: | Most ferrite & iron powder cores look same. So if unsure about material properties, its most safe bet to purchase low to medium frequency beads from distributors such as: | ||
*Digikey | *Digikey | ||
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* Laird-Signal Integrity Products | * Laird-Signal Integrity Products | ||
* Fair-Rite | * Fair-Rite | ||
| + | ==Usage with VSD-E/XE drives== | ||
| + | To solve an EMI problem its good to have selection of beads that can be tried on different cables. Most typical placement for beads: | ||
| + | *USB adapter | ||
| + | *CMD cable | ||
| + | *Encoder cable | ||
| + | *Motor output cable (all motor wires through core, multiple turns) | ||
| + | *HV DC power supply cable (+ and - leads through core, multiple turns) | ||
==See also== | ==See also== | ||
*[[Wikipedia:Ferrite bead]] | *[[Wikipedia:Ferrite bead]] | ||
Revision as of 22:39, 18 April 2012
EMI suppression cores a.k.a. ferrite beads are an efficient way to reduce high frequency interference from wiring. Adding ferrute beads to signal & power wiring is recommended if signal reliability problems are encountered.
Selection
For motor control applications it is recommended to get low to medium frequency ferrite beads for maximum efficiency.
- Preferred types
- Core material designed for low to medium frequency bands (attenuation between 1-300 MHz)
- Large enough to fit cable multiple rounds through it
- Avoid
- Core material designed for high frequency bands (above 300 MHz)
- Inductor cores - will just add inductance and make things worse
- Iron powder cores
Where to find suitable cores
Most ferrite & iron powder cores look same. So if unsure about material properties, its most safe bet to purchase low to medium frequency beads from distributors such as:
- Digikey
- Mouser
- Farnell
Some popular ferrite bead brands:
- Laird-Signal Integrity Products
- Fair-Rite
Usage with VSD-E/XE drives
To solve an EMI problem its good to have selection of beads that can be tried on different cables. Most typical placement for beads:
- USB adapter
- CMD cable
- Encoder cable
- Motor output cable (all motor wires through core, multiple turns)
- HV DC power supply cable (+ and - leads through core, multiple turns)
