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
