Watlow 942 Series - Noise Guidelines; How to Check for Ground Loops; Noise Suppression Devices Available From Watlow

Appendix
52
WATLOW Series 942 User's Manual
How to Check for Ground Loops
To check for ground loops, disconnect the ground wire at the ground termina-
tion. Measure the resistance from the wire to the point where it was connected.
The ohmmeter should read a high ohm value. If you have a low ohm value
across this gap, there is at least one ground loop present in your system.
Or check for continuity; your reading should be "open." If you do find continu-
ity, you must now begin looking for the ground loops. Begin disconnecting
ground in the system one at a time, checking for continuity after each discon-
nection. When continuity reads "open" you have eliminated the ground loop(s).
Also, as you reconnect grounds, keep making the continuity test. It is possible
to reconnect a ground loop.
Noise Suppression Devices Available From Watlow
Watlow Controls stocks a few key noise suppression parts. You may order
these by calling your local Watlow distributor.
Noise Guidelines
Table 6 -
Noise Suppression
Device Ratings
Item Electrical Ratings Part Number
Differential Mode Line Filter Refer to the Islatrol listing above.
Metal Oxide Varistor 150V, 80 Joule 0802-0273-0000
MOV130V, 38 Joule 0802-0304-0000
MOV275V, 75 Joule 0802-0266-0000
MOV275V, 140 Joule 0802-0405-0000