Watlow 12LS Controller - Manual (Page 21)

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3. Separate the 120 vac power leads from the low level input and outputs leads from the ANAFAZE. Do not run the
digital outputs or PID control outputs leads in the same wire bundle as any 120 vac wires. Inputs leads should never be
run in the same bundle with any high power leads. See 3.3.3.
4. If, E-M relays are required and must be in the same panel as the ANAFAZE equipment, use a .01 uF at 1000 vdc or
higher vdc disk capacitor in series with a 47 ohm 1/2 W resistor across the NO contacts of the relay load contacts. This
is the most important step in suppressing RFI from relay contacts. This network is known as arc suppresser or snubber
networks.
5. Use of other voltage suppressing devices may also be used, but are not normally required. A device known as a
MOV rated at 130 vac for 120 vac control circuits may be placed across the load. This will limit the peak ac voltage to
about 180 vac. A device known as a transorb (back to back zeners) may be used across the digital output. The rating of
5 vdc should be used. This will limit the dc voltage to 5 vdc on the digital output loop.
See diagrams for proper placement of the above devices. The parts for RFI suppression are available from ANAFAZE.
The above steps should eliminate any noise problems that might be present with using E-M relays. If, problems
persists and/or any questions about the above steps arises, please call ANAFAZE.
DIAGRAM OF TYPICAL DIGITAL OUTPUTS WITH RFI SUPPRESSION